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Reductions in knee joint forces with weight loss are attenuated by gait adaptations in class III obesity
... 19,40,[42][43][44][45][46] tTFJ compressive force was determined as the summed vertical and anterior-posterior components of the muscle forces and TFJ reaction forces acting perpendicular to the tibial plateau. 35,36 Total TFJ compressive force was then parsed to medial and lateral tibial compartments by applying the tTFJ compressive force to contact points on the medial and lateral tibial plateaus at 25% and 75% of subject-specific knee joint width measurements, respectively, in a manner that reproduced the net frontal plane knee joint moment. 40,42,47,48 Peak tTFJ contact force and impulse estimates using this model are within 3% and 7%, respectively, of in vivo gait data from an individual with an instrumented knee prosthesis, while peak mTFJ contact force and impulse are within 7% and 4% of in vivo gait data. ...
... The quadriceps forces had a unique response to greater load, which were consistent in curve shape with the literature. 35,42 There was a 1.7:1 and a 2.1:1 increase in peak quadriceps force to weight added, with the 30% condition inducing a 40% increase in peak quadriceps force. The quadriceps exhibited 2 to 3 times greater peak force than the hamstrings, subsequently providing a greater contribution to first peak tTFJ contact force, which is consistent with the literature. ...
... The quadriceps exhibited 2 to 3 times greater peak force than the hamstrings, subsequently providing a greater contribution to first peak tTFJ contact force, which is consistent with the literature. 35,36,42 Therefore, peak quadriceps force was a contributing factor that helps explain the change in first peak tTFJ contact force ratio from 3.2:1 to 3.6:1 between the 15% and 30% load conditions. The curvilinear increase with tTFJ impulse is most likely due to the ratios of quadriceps impulse and knee flexion increases across the conditions. ...
Chronic exposure to high tibiofemoral joint (TFJ) contact forces can be detrimental to knee joint health. Load carriage increases TFJ contact forces, but it is unclear whether medial and lateral tibiofemoral compartments respond similarly to incremental load carriage. The purpose of our study was to compare TFJ contact forces when walking with 15% and 30% added body weight. Young healthy adults (n = 24) walked for 5 minutes with no load, 15% load, and 30% load on an instrumented treadmill. Total, medial, and lateral TFJ contact peak forces and impulses were calculated via an inverse dynamics informed musculoskeletal model. Results of 1-way repeated measures analyses of variance ( α = .05) demonstrated total, medial, and lateral TFJ first peak contact forces and impulses increased significantly with increasing load. Orthogonal polynomial trends demonstrated that the 30% loading condition led to a curvilinear increase in total and lateral TFJ impulses, whereas medial first peak TFJ contact forces and impulses responded linearly to increasing load. The total and lateral compartment impulse increased disproportionally with load carriage, while the medial did not. The medial and lateral compartments responded differently to increasing load during walking, warranting further investigation because it may relate to risk of osteoarthritis.
... OAK has a multifactorial etiology, with obesity proposed as the main risk factor for its development because of biomechanical and biochemical changes [4,5]. Regarding biomechanics, Bindawas and DeVita showed that the load imposed on the knee is proportional to the body mass [6,7]. Messier, in contrast, identified that each kilogram of body mass increases the compressive load on the knee by 4 kg during the performance of daily activities. ...
... Excess body mass can cause biomechanical changes in lower limb joints, especially in individuals who have degenerative joint pathologies such as OA, which consequently change the gait pattern. The mechanisms that link OAK, obesity and gait are not fully understood, but literature shows that the loss of 34% of body mass in obese individuals reduces 67% of the compressive load on the knee, facilitating gait performance [7]. ...
... In contrast, obesity is a risk factor that can be modified in this population. Devita showed that a loss of 34% of body mass in obese individuals reduces in 67% the compressive load on the knee, which could contribute to a more efficient gait pattern [7]. ...
Introduction:
Knee osteoarthritis (OAK) is one of the most prevalent rheumatic diseases in the population, characterized by functional limitation and gait difficulties with profound clinical relevance, as walking is the most frequently performed daily activity. These functional limitations may be more pronounced when the disease is associated with obesity.
Objective:
To investigate the effect of different body weight suspension percentages on gait biomechanical variables and co-contraction percentages in women with OAK.
Method:
Fourteen women aged 50-75 years, with a body mass index between 26 and 35 and radiological diagnosis of OAK participated in the study. On the first day, anamnesis and familiarization with gait on the treadmill was performed. On the second day, treadmill gait assessment was performed using partial body weight support (SPPC) in three conditions-15%, 30%, and 45% suspension. During the evaluation, electromyographic and kinematic data were collected. The variables analyzed were percentage of hip (gluteus maximus/rectus femoris), knee (femoral biceps/vastus lateralis), and ankle (anterior tibial/lateral gastrocnemius), and length and step widths. A one-way analysis of variance was conducted, with a significance level of p < 0.05.
Results:
There was no significant difference in the length and step width and the level of co-contraction between the running conditions analyzed.
Conclusion:
Body weight suspension using SPPC during treadmill running did not alter the biomechanical variables of the gait of women with OAK.
... Following approval by the institutional review board of Duke University Medical Center, eight subjects (five males and three females; mean age 30 years, range 23-43; mean height 70 in., range 64-74) with a normal BMI (mean 22.2; range [18][19][20][21][22][23][24][25] and seven subjects (three males and four females; mean age 32, range 22-45; mean height 66 in., range 63-71) with a high BMI (mean 32.8; range [30][31][32][33][34][35][36], who were otherwise healthy, were recruited for participation in this study. The normal BMI and high BMI groups were statistically significantly different with regard to BMI (P <0.0001, t test). ...
... Gait analysis studies have been previously used to approximate joint reaction forces in response to obesity [34][35][36]. For example, Harding et al. demonstrated that Fig. 4 a, b Tibial cartilage pre-exercise thickness was significantly correlated with body mass index (BMI) (P <0.01) and body fat percentage (P <0.01). ...
... c, d Femoral cartilage pre-exercise thickness was not significantly correlated with BMI (P = 0.79) or body fat percentage (P = 0.71) high BMI is associated with higher absolute tibiofemoral compressive forces by using a sagittal plane contact force model [34]. In a separate weight loss study, DeVita et al. demonstrated that weight loss of approximately 34% of initial body weight reduced maximum compressive forces in the knee as measured through gait analysis techniques, but these changes were later attenuated by gait adaptations following weight loss [35]. Additionally, Liukkonen et al. showed that weight loss induced by bariatric surgery altered knee kinetics and kinematics during gait [36]. ...
Abstract Background Obesity is a primary risk factor for the development of knee osteoarthritis (OA). However, there remains a lack of in vivo data on the influence of obesity on knee cartilage mechanics and composition. The purpose of this study was to determine the relationship between obesity and tibiofemoral cartilage properties. Methods Magnetic resonance images (3T) of cartilage geometry (double-echo steady-state) and T1rho relaxation of the knee were obtained in healthy subjects with a normal (n = 8) or high (n = 7) body mass index (BMI) before and immediately after treadmill walking. Subjects had no history of lower limb injury or surgery. Bone and cartilage surfaces were segmented and three-dimensional models were created to measure cartilage thickness and strain. T1rho relaxation times were measured before exercise in both the tibial and femoral cartilage in order to characterize biochemical composition. Body fat composition was also measured. Results Subjects with a high BMI exhibited significantly increased tibiofemoral cartilage strain and T1rho relaxation times (P
... According to our results, the individuals affected by obesity showed a body rotation behavior similar to that of healthy weight participants, as suggested by the results relative to the pelvis and shoulders rotation as well as by the A/Pcrit. However, differences could be observed in terms of speed and step length, in line with previous studies [44][45][46][47][48][49][50]. Thus, the various components of the body schema might be variously affected in obesity. ...
... Individuals affected by obesity may adopt a walking strategy to minimize fatigue, specifically when they are required to walk at faster speeds [46], or to maintain biomechanical stability [47,49]. Interestingly, it was reported in the literature that walking parameters change after body mass loss: individuals increased stride length and walking velocity in the self-selected velocity [48], specifically when the obstacles were far away from the body [49]. Following the hypothesis of a strategy minimizing risk adopted during the task, we would hypothesize that individuals affected by obesity did not alter their walking kinematics because it would increase their risk of losing trunk stability and, consequently, of falling. ...
... Otherwise, if we had scaled the apertures referring to the largest body parts for each individual, the target would be different between participants, affecting the reliability of the experiment. Generally, previous studies in the field of obesity have focused on the range of motion of hip [52], pelvis [46], waist [47], and not shoulders, also when the performance was matched with healthy participants: this fact is due to the role of these body parts in determining the movement of individuals with larger body mass [46][47][48][49]52]. Finally, from a psychological point of view, pelvis (and not shoulders) is a sensitive body part in terms of negative emotions and feelings about size and shape [11,40,68]; thus, if body schema and body image interact [31][32], the emotional meaning related to specific body parts in the individual's experience would be taken in account. ...
Objective:
Conscious perception of our own body, also known as body image, can influence body-scaled actions. Certain conditions such as obesity are frequently accompanied by a negative body image, leaving open the question if body-scaled actions are distorted in these individuals.
Methods:
To shed light on this issue, we asked individuals affected by obesity to process dimensions of their own body in a real action: they walked in a straight-ahead direction, while avoiding collision with obstacles represented by door-like openings that varied in width.
Results:
Participants affected by obesity showed a body rotation behavior similar to that of the healthy weighted, but differences emerged in parameters such as step length and velocity.
Conclusion:
When participants with obesity walk through door-like openings, their body parts rotation is scaled according to their physical body dimensions; however, they might try to minimize risk of collision. Our study is in line with the hypothesis that unconscious body-scaled actions are related to emotional, cognitive and perceptual components of a negative body image.
... Weight loss also affected the mechanical pathway by reducing peak knee compressive loads by more than 200 N per step relative to the exercise comparator group, even as preferred walking speed increased. This empirical evidence supported earlier studies that showed two-to-four times the reduction in peak knee compressive forces for each kg of weight loss (Aaboe et al., 2011;DeVita et al., 2016;Messier et al., 2005a). Aaboe et al. (2011) also investigated the biomechanical response to 16 weeks of intensive weight loss (mean weight loss 13.5%) in obese knee OA patients and found significantly lower (7%) knee compressive forces and internal knee abduction moments (12%). ...
... Henriksen et al. (2013) found that a subset of knee OA patients actually increased joint loading after substantial weight loss, presumably due to increased walking speed and improved knee function. In contrast, others have shown significant reductions in weight leads to lower knee joint loads and faster walking speeds (DeVita et al., 2016;Messier et al., 2018). We seek to clarify the biomechanical locomotion responses to weight loss with this study, the purpose which was to examine the long-term effect of intensive dietary weight loss, with or without exercise, on hip, knee, and ankle spatiotemporal, kinematic, and kinetic variables. ...
The Intensive Diet and Exercise for Arthritis (IDEA) trial was an 18-month randomized controlled trial that enrolled 454 overweight and obese older adults with symptomatic and radiographic knee osteoarthritis (OA). Participants were randomized to either exercise (E), intensive diet-induced weight loss (D), or intensive diet-induced weight loss plus exercise (D + E) interventions. We previously reported that the clinical benefits of D + E were significantly greater than with either intervention alone (e.g., greater pain reduction, and better function, mobility, and health-related quality of life). We now test the hypothesis that D + E has greater overall benefit on gait mechanics compared to either intervention alone. Knee joint loading was analyzed using inverse dynamics and musculoskeletal modeling. Analysis of covariance determined the interventions' effects on gait. The D + E group walked significantly faster at 18-month follow-up (1.35 m s-1) than E (1.29 m s-1, p = 0.0004) and D (1.31 m s-1, p = 0.0007). Tibiofemoral compressive impulse was significantly lower (p = 0.0007) in D (1069 N s) and D + E (1054 N s) compared to E (1130 N s). D had significantly lower peak hip external rotation moment (p = 0.01), hip abduction moment (p = 0.0003), and peak hip power production (p = 0.016) compared with E. Peak ankle plantar flexion moment was significantly less (p < 0.0001) in the two diet groups compared with E. There also was a significant dose-response to weight loss; participants that lost >10% of baseline body weight had significantly (p = 0.0001) lower resultant knee forces and lower muscle (quadriceps, hamstring, and gastrocnemius) forces than participants that had less weight loss. Compared to E, D produces significant load reductions at the hip, knee, and ankle; combining D with E attenuates these reductions, but most remain significantly better than with E alone.
... Weight losses of 14-33% have previously been reported to reduce TFJ loads approximately twice as much as the lost weight. 43,44 Together, present and past data provide reasonable support for the proposition that changes in TFJ loads are approximately twice as large as changed mass, regardless of weight loss or gain. Data in the present investigation are the only published reports to date on changes in added mass relating to Achilles tendon forces or PFJ loads. ...
... 1 We deliberately chose a standardized gait speed for all test conditions to investigate the independent effects of the load carriage on knee loads in the absence of changes in gait speed. 43 Most importantly, self-selected gait speeds may not accurately reflect Soldier demands when walking within formation where gait speed is indeed standardized. ...
Introduction
Longer steps with load carriage is common in shorter Soldiers when matching pace with taller Soldiers whereas shorter steps are hypothesized to reduce risk of injury with load carriage. The effects of load carriage with and without step length manipulation on loading patterns of three commonly injured structures were determined: Achilles tendon, patellofemoral joint (PFJ) and medial tibiofemoral joint (mTFJ).
Materials and Methods
ROTC Cadets (n = 16; 20.1 years ± 2.5) walked with and without load carriage (20-kg). Cadets then altered preferred step lengths ±7.5% with load carriage. Achilles tendon, PFJ and mTFJ loads were estimated via musculoskeletal modeling.
Results
Large increases in peak Achilles tendon load (p < 0.001, d = 1.93), Achilles tendon impulse per 1-km (p < 0.001, d = 0.91), peak mTFJ load (p < 0.001, d = 1.33), and mTFJ impulse per 1-km (p < 0.001, d = 1.49) were noted with load carriage while moderate increases were observed for the PFJ (peak: p < 0.001, d = 0.69; impulse per 1-km: p < 0.001, d = 0.69). Shortened steps with load carriage only reduced peak Achilles tendon load (p < 0.001, d = –0.44) but did not reduce Achilles impulse per km due to the resulting extra steps and also did not reduce peak or cumulative PFJ and mTFJ loads (p > 0.05). Longer steps with load carriage increased PFJ loads the most (p < 0.001, d = 0.68–0.75) with moderate increases in mTFJ forces (p < 0.001, d = 0.48–0.63) with no changes in Achilles tendon loads (p = 0.11–0.20).
Conclusion
A preferred step length is the safest strategy when walking with load carriage. Taking a shorter step is not an effective strategy to reduce loading on the Achilles tendon, PFJ, and mTFJ.
... In both the early and late stance phases, these elevated muscle activities may serve as a compensatory strategy adopted by obese individuals, suggesting a potential lack of confidence in joint stability and utilization when compared to individuals who are healthy or even overweight 88,89 . However, the computed augmentation of the muscle forces over the stance phase is still less than the expected one if it is compared with the percentage of the achieved mass augmentation (average of 25% for overweight and 45% for obese participants), which is endorsing earlier observation where some obese individuals reorganizing their neuromuscular function to most likely reduce the muscles fatigue possibility and joint loading 34,90 . Our predicted results are consistent with previous EMG measurements 91 . ...
Knee osteoarthritis (OA) and obesity are major public health concerns that are closely intertwined. This intimate relationship was documented by considering obesity as the most significant preventable risk factor associated with knee OA. To date, however, the effects of obesity on the knee joint's passive-active structure and cartilage loading have been inconclusive. Hence, this study investigates the intricate relationship between obesity and knee OA, centering on the biomechanical changes in knee joint active and passive reactions during the stance phase of gait. Using a subject-specific musculoskeletal and finite element approach, muscle forces, ligament stresses, and articular cartilage contact stresses were analyzed among 60 individuals with different body mass indices (BMI) classified under healthy weight, overweight, and obese categories. Our predicted results showed that obesity significantly influenced knee joint mechanical reaction, increasing muscle activations, ligament loading, and articular cartilage contact stresses, particularly during key instances of the gait cycle—first and second peak loading instances. The study underscores the critical role of excessive body weight in exacerbating knee joint stress distribution and cartilage damage. Hence, the insights gained provide a valuable biomechanical perspective on the interaction between body weight and knee joint health, offering a clinical utility in assessing the risks associated with obesity and knee OA.
... 32 Longer step length is also related to greater knee loading (ie, knee contact forces or knee joint moments), which may explain its relation to pain worsening. 33,34 Interventions to reduce step and stride length have been proposed for people with knee OA. 35,36 Dominant frequency is closely tied to step duration and cadence; lower dominant frequency reflects greater step duration and lower cadence. 37 So individuals who spend more time with each step will have a lower dominant frequency. ...
Objective
The objective of this study was to identify gait alterations related to worsening knee pain and worsening physical function, using machine learning approaches applied to wearable sensor–derived data from a large observational cohort.
Methods
Participants in the Multicenter Osteoarthritis Study (MOST) completed a 20‐m walk test wearing inertial sensors on their lower back and ankles. Parameters describing spatiotemporal features of gait were extracted from these data. We used an ensemble machine learning technique (“super learning”) to optimally discriminate between those with and without worsening physical function and, separately, those with and without worsening pain over two years. We then used log‐binomial regression to evaluate associations of the top 10 influential variables selected with super learning with each outcome. We also assessed whether the relation of altered gait with worsening function was mediated by changes in pain.
Results
Of 2,324 participants, 29% and 24% had worsening knee pain and function over two years, respectively. From the super learner, several gait parameters were found to be influential for worsening pain and for worsening function. After adjusting for confounders, greater gait asymmetry, longer average step length, and lower dominant frequency were associated with worsening pain, and lower cadence was associated with worsening function. Worsening pain partially mediated the association of cadence with function.
Conclusion
We identified gait alterations associated with worsening knee pain and those associated with worsening physical function. These alterations could be assessed with wearable sensors in clinical settings. Further research should determine whether they might be therapeutic targets to prevent worsening pain and worsening function.
... In the elderly, sarcopenia is considered the main factor contributing to alterations in dynamic balance during walking [54], but other factors such as changes in joint movements are also involved. It is, therefore, possible that muscle strengthening [55], as well as joint range of motion improvement [56] may be a satisfactory modality to improve balance abilities in the elderly via balance and motor exercises. ...
Background
Aging often leads to cognitive function decline, sensory structure deterioration, and musculoskeletal system weakening. This impacts postural control during static and dynamic activities like walking, increasing the fall risk among the elderly. Older adults with mild cognitive impairment (MCI) face an elevated fall risk and cognitive decline, magnifying the public health concern.
Objective
This study aimed to explore solutions by investigating the effects of a multi-component physical activity program on cognitive and motor functions in MCI patients.
Methods
Twenty-three participants were enrolled in the study and assigned into two groups: an intervention group (n = 13; age = 85.7±5.5 years) and a control group (n = 9; age = 85±6.7 years). The study spanned two months, with participants engaging in three 60-minute weekly physical exercise sessions. The intervention focused on improving proprioception, muscle strength, and balance.
Results
Results demonstrated significant enhancements in physical performance, fall risk reduction, and balance (p < 0.05). Various tests, including the timed up and go test, Unipedal Stance test, Tinetti test, Short Physical Performance Battery, and 6-minute walking test, indicated these improvements. Cognitive function was evaluated with the Mini-Mental State Examination, revealing non-significant progress (p > 0.05). Predictive models for outcomes were developed using linear regression analysis during the follow-up stage.
Conclusions
This study underscores the effectiveness of a multi-component physical activity program encompassing balance, proprioception, and muscle-strengthening exercises as a non-pharmaceutical approach in improving balance skills and playing a key role in mitigating the risk of falls among old adults with MCI.
... BW loss has been shown to improve function and reduce knee joint loading (Atukorala et al., 2016;Messier et al., 2011). Additionally, peak total contact force reduces 1-4-fold with every unit of weight loss (Aaboe et al., 2011;DeVita et al., 2016;Messier et al., 2005). Applying this ratio to 7.7-10.2% ...
Medial knee contact force (MCF) is related to the pathomechanics of medial knee osteoarthritis. However, MCF cannot be directly measured in the native knee, making it difficult for therapeutic gait modifications to target this metric. Static optimization, a musculoskeletal simulation technique, can estimate MCF, but there has been little work validating its ability to detect changes in MCF induced by gait modifications. In this study, we quantified the error in MCF estimates from static optimization compared to measurements from instrumented knee replacements during normal walking and seven different gait modifications. We then identified minimum magnitudes of simulated MCF changes for which static optimization correctly identified the direction of change (i.e., whether MCF increased or decreased) at least 70% of the time. A full-body musculoskeletal model with a multi-compartment knee and static optimization was used to estimate MCF. Simulations were evaluated using experimental data from three subjects with instrumented knee replacements who walked with various gait modifications for a total of 115 steps. Static optimization underpredicted the first peak (mean absolute error = 0.16 bodyweights) and overpredicted the second peak (mean absolute error = 0.31 bodyweights) of MCF. Average root mean square error in MCF over stance phase was 0.32 bodyweights. Static optimization detected the direction of change with at least 70% accuracy for early-stance reductions, late-stance reductions, and early-stance increases in peak MCF of at least 0.10 bodyweights. These results suggest that a static optimization approach accurately detects the direction of change in early-stance medial knee loading, potentially making it a valuable tool for evaluating the biomechanical efficacy of gait modifications for knee osteoarthritis.
... This investigation therefore strongly supports the long-held notion regarding the negative effects of obesity on tibiofemoral cartilage health. This investigation showed BMI to be a significant predictor of cartilage loading indices in obese individuals and previous analyses importantly having revealed that weight loss is able to mediate significant reductions in medial tibiofemoral loading [69,70]. Taking into account the debilitating and painful presentation of knee OA [7] as well as its fiscal healthcare implications [10], the findings from this study therefore strongly advocate for the implementation of effective weight management programs into long-term musculoskeletal management strategies. ...
This study examined the effects of obesity on medial tibiofemoral cartilage mechanics and longitudinal failure probability, using musculoskeletal simulation and probabilistic failure modelling approaches. The current investigation examined twenty obese females (BMI>30.0kg/m2) and 20 healthy weight (BMI<25.0kg/m2) females. Kinematic data during walking were collected using a motion capture system and ground reaction forces using a force plate. Medial tibiofemoral loading was explored using musculoskeletal simulation and cartilage probability via probabilistic modelling. Comparisons between groups were undertaken using linear mixed effects models. Net peak medial tibiofemoral cartilage force, stress and strain were significantly greater in the obese group (force=2013.92N, stress=3.03MPa & strain=0.25), compared to health weight (force=1493.21N, stress 2.26MPa & strain=0.19). In addition, probability of medial tibiofemoral cartilage failure was significantly greater in the obese group (42.98%) compared to healthy weight (11.63%). The findings from the current investigation show that obesity has a profoundly negative influence on longitudinal medial knee cartilage health and strongly advocate for the implementation of effective weight management programs into long-term musculoskeletal management strategies.
... Simulation-inspired coordination retraining is an effective and flexible way to alter joint loading. The individuals who adopted the gastrocnemius avoidance coordination pattern reduced KCF P2 by an average of 0.38 BW, which is similar to the joint-offloading effect of losing 15-38% of bodyweight [45][46][47] . Similar reductions in medial and total KCF have been achieved with kinematic gait modifications 48,49 or assistive devices 15,48,50 , but coordination retraining does not require conspicuous kinematic changes or lifestyle changes that often hinder patient adoption 18,51 . ...
Humans typically coordinate their muscles to meet movement objectives like minimizing energy expenditure. In the presence of pathology, new objectives gain importance, like reducing loading in an osteoarthritic joint, but people often do not change their muscle coordination patterns to meet these new objectives. Here we use musculoskeletal simulations to identify simple changes in coordination that can be taught using electromyographic biofeedback, achieving the therapeutic goal of reducing joint loading. Our simulations predicted that changing the relative activation of two redundant ankle plantarflexor muscles—the gastrocnemius and soleus—could reduce knee contact force during walking, but it was unclear whether humans could re-coordinate redundant muscles during a complex task like walking. Our experiments showed that after a single session of walking with biofeedback of summary measures of plantarflexor muscle activation, healthy individuals reduced the ratio of gastrocnemius-to-soleus muscle activation by 25 ± 15% (p = 0.004, paired t test, n = 10). Participants who walked with this “gastrocnemius avoidance” gait pattern reduced late-stance knee contact force by 12 ± 12% (p = 0.029, paired t test, n = 8). Simulation-informed coordination retraining could be a promising treatment for knee osteoarthritis and a powerful tool for optimizing coordination for a variety of rehabilitation and performance applications.
... Experiments and studies have shown that the weight reduction in obese people is associated with relieving pain in the lower back, knee, ankles, and feet [29,40]. A study performed by DeVita et al. [12] showed that decrease the knee force in relation to the weight loss and increase the walking quality. This indicated the importance of studying the effect of obesity on the different components of gait quality. ...
Study aim : The aim of the current study is to explore the effect of obesity on spatiotemporal parameters of gait in obese young female students.
Material and methods : A cross-sectional study with fifteen obese female university students (mean age = 20.3 ± 1.6, mean BMI = 36.2 ± 4.6) and fifteen normal weight female university students (mean age = 20.9 ± 2, mean BMI = 22.6 ± 2.4) was conducted. The spatiotemporal gait parameters were evaluated using GAITRite® walkway (Frankline, USA, Model No. TR30RAM090 with software version 4.89C2).
Results : Independent sample t-test showed statistical significant differences in some spatiotemporal gait parameters between normal and obese subjects with statistically significant reductions of single-limb support time, step length, stride length, and velocity in the obese subjects rather than normal subjects (p = 0.031, 0.015, 0.039, and 0.002, respectively). Moreover, there were statistically significant increases of step time, stride time in the obese subjects rather than the normal subjects (p = 0.038, 0.017, respectively).
Conclusion : These results suggested that obesity is a factor that adversely affects the spatiotemporal gait parameters in the obese young female. This may be contributed to decrease the joints’ mobility and increase the incidence of joint osteoarthritis. So, it is recommended to encourage the sufficient physical activity and weight reduction among obese female students.
... Les résultats de cette étude confirment que les paramètres spatio-temporels, notamment Plusieurs études ont expliqué que l'augmentation de la masse corporelle induit des modifications de la biomécanique de la marche (DeVita & Hortobágyi, 2003;DeVita, Rider, & Hortobágyi, 2016;Harding et al., 2012;Peyrot et al., 2009). Les résultats de cette étude confirment cette observation, montrant que l'excès de la masse corporelle induit une modification au niveau de la géométrie des pas lors de la marche qui se traduit par une augmentation de la largeur des pas (+40% chez GO par rapport au GC). ...
It is well established that obesity and
aging, separately, impair individuals’ balance and
walking abilities. These alterations are associated
with a greater difficulty in performing daily life
activities. However, the magnitude of the effects
of the combination of aging and obesity on
functional abilities, as observed in obese elderly,
requires further investigations. Through this
thesis work, we, first, showed that obesity
presents an additional constraint to age
throughout the process of stabilization and
walking in elderly. This aggravates the functional
limitations of the obese elderly in daily life
activities.
Then, we demonstrated that an adapted
physical activity program based on balance,
muscular reinforcement and mobility
exercises in obese elderly improves their
lower limb neuromuscular capacities and
consequently optimizes balance and walking
abilities.
... Plusieurs études ont expliqué que l'augmentation de la masse corporelle induit des modifications de la biomécanique de la marche (DeVita & Hortobágyi, 2003;DeVita, Rider, & Hortobágyi, 2016;Harding et al., 2012;Peyrot et al., 2009). Les résultats de cette étude confirment cette observation, montrant que l'excès de la masse corporelle induit une modification au niveau de la géométrie des pas lors de la marche qui se traduit par une augmentation de la largeur des pas (+40% chez GO par rapport au GC). ...
... 25 Weight loss is also associated with a decrease in knee joint forces that is at least equal to, or even up to four times, the absolute weight lost. 26,27 However, overweight, and obese persons may find it difficult to embark on physical activity for weight loss, as they experience pain in their knees on walking. Upon seeking medical attention, they may be prescribed analgesia and advised to avoid aggravating activities. ...
The rate of overweight and obesity is increasing worldwide, with significant health impact. Obesity is a risk factor for morbidity and mortality and weight loss should take a multi-pronged approach, including dietary control and physical activity. The lack of physical activity, sedentary behaviour, as well as poor cardiorespiratory fitness are all independent risk factors for morbidity and mortality as well, thus it is important to advise lifestyle changes to address these issues. Most individuals who have no contraindications can embark on light- to moderate-intensity physical activity without the need for medical clearance. Specific advice on physical activity should be given, targeting the individual, and this can be done using the FITT (frequency, intensity, time, type) principle. Physical activity should also be reviewed regularly and progressed gradually to target physical activity guidelines. Individuals should also be encouraged to replace sedentary behaviour with at least light-intensity physical activity whenever possible.
... The ability of a gastrocnemius avoidance coordination pattern to reduce knee contact force suggests that coordination retraining could be used to reduces joint contact forces other arthritic joints throughout the body. The 0.38BW or 12% reduction in KCFP2 is similar to the joint-offloading effect of losing 15-38% of bodyweight [40][41][42] . The reduction in KCFP2 is similar to what has been achieved with kinematic gait modifications 43,44 or assistive devices 14,43,45 , but does not require conspicuous kinematic or lifestyle changes that often hinder patient adoption 17,46 . ...
Humans typically coordinate their muscles to meet movement objectives like minimizing energy expenditure. In the presence of pathology, new objectives gain importance, like reducing loading in an osteoarthritic joint, but people often do not change their muscle coordination patterns to meet these new objectives. Here we use musculoskeletal simulations to identify simple changes in coordination that can be taught by providing feedback of electromyographic activity to achieve a therapeutic goal-reducing joint loading. Our simulations predicted that changing the relative activation of the redundant ankle plantarflexors could reduce knee contact force during walking, but it was unclear whether humans could re-coordinate redundant muscles during a complex task like walking. With simple biofeedback of electromyographic activity, healthy individuals reduced the ratio of gastrocnemius to soleus muscle activation by 25±15% (p=0.004). The resulting "gastrocnemius avoidance" gait pattern reduced the late-stance peak of simulation-estimated knee contact force by 12±12% (p=0.029). Simulation-informed muscle coordination retraining could be a promising treatment for knee osteoarthritis and a powerful tool for optimizing coordination for a variety of rehabilitation and performance applications.
... Weight loss has favorable impacts on pain and biomechanics of the lower extremity, including decreased foot plantar loading pressure, increased ankle plantarflexion, knee joint motion (maximal knee flexion), compressive force and peak moments around the hip and knee. [83][84][85] However, evidence reflecting the impact of weight loss in AT-related painful MSK disorders is scarce and unclear. ...
Description Adipose tissue (AT) has diverse and important functions in body insulation, mechanical protection, energy metabolism and the endocrine system. Despite its relative abundance in the human body, the clinical significance of AT in musculoskeletal (MSK) medicine, particularly its role in painful MSK conditions, is under-recognized. Pain associated with AT can be divided into intrinsic (AT as a primary pain generator), extrinsic (AT as a secondary pain generator) or mixed origin. Understanding AT as an MSK pain generator, both by mechanism and its specific role in pain generation by body region, enhances the clinical decision-making process and guides therapeutic strategies in patients with AT-related MSK disorders. This article reviews the existing literature of AT in the context of pain generation in the lower back and lower extremity to increase clinician awareness and stimulate further investigation into AT in MSK medicine.
... Plusieurs études ont expliqué que l'augmentation de la masse corporelle induit des modifications de la biomécanique de la marche (DeVita & Hortobágyi, 2003;DeVita, Rider, & Hortobágyi, 2016;Harding et al., 2012;Peyrot et al., 2009). Les résultats de cette étude confirment cette observation, montrant que l'excès de la masse corporelle induit une modification au niveau de la géométrie des pas lors de la marche qui se traduit par une augmentation de la largeur des pas (+40% chez GO par rapport au GC). ...
Au regard de la littérature, il est bien identifié que l’obésité et le vieillissement altèrent les capacités de l’équilibre et de la marche des individus, altérations potentiellement associées à une plus grande difficulté à réaliser les activités de la vie quotidienne. Nous pouvons alors nous interroger sur les effets combinés du vieillissement et de l’obésité sur les capacités de l’équilibre et de la marche. Dans ce travail de thèse, nous avons, tout d’abord, montré que l’obésité présente une contrainte additionnelle sur les modifications des capacités de l’équilibre et de la marche liées au vieillissement, favorisant l’augmentation des limitations fonctionnelles chez une population âgée obèse. Ensuite, nous avons rapporté qu’un programme d’activités physiques adaptées basé sur des exercices d’équilibre, de renforcement musculaire et de motricité était une modalité de prise en charge efficace chez les personnes âgées obèses, permettant d’améliorer leurs capacités neuromusculaires au niveau des membres inférieurs, et par conséquent, leurs capacités d’équilibre et de la marche.
... For example, Delextrat et al. [56] found a large and significant increase in gait velocity after their weight loss intervention for youth with obesity. However, increased velocity actually increases the force on the knee [59], which could potentially put these youth at greater risk of injury. The reduction in gait velocity that was observed in this study may therefore be beneficial for this population. ...
Obesity negatively impacts the kinematics and kinetics of the lower extremities in children and adolescents. Although yoga has the potential to provide several distinct benefits for children with obesity, this is the first study to examine the benefits of yoga for gait (primary outcome) in youths with obesity. Secondary outcomes included health-related quality of life (HRQoL), physical activity, and pain. Feasibility and acceptability were also assessed. Nine youths (11–17 years) participated in an eight-week Iyengar yoga intervention (bi-weekly 1-h classes). Gait, HRQOL (self and parent-proxy reports), and physical activity were assessed at baseline and post-yoga. Pain was self-reported at the beginning of each class. Significant improvements were found in multiple gait parameters, including hip, knee, and ankle motion and moments. Self-reported and parent-proxy reports of emotional functioning significantly improved. Time spent in physical activity and weight did not change. This study demonstrates that a relatively brief, non-invasive Iyengar yoga intervention can result in improved malalignment of the lower extremities during ambulation, as well as in clinically meaningful improvements in emotional functioning. This study extends current evidence that supports a role for yoga in pediatric obesity.
... For example, Delextrat et al. [56] found a large and significant increase in gait velocity after their weight loss intervention for youth with obesity. However, increased velocity actually increases the force on the knee [59], which could potentially put these youth at greater risk of injury. The reduction in gait velocity that was observed in this study may therefore be beneficial for this population. ...
Childhood obesity in the United States has more than tripled in the past three decades. Differences in lower extremity kinematics between obese and nonobese children during walking have been investigated, but the validity of using the gait deviation index (GDI) for measuring gait in obese children has not been explored. Nine obese children (13.9 ± 2.4 years old) with a body mass index of 33.3 ± 3.5 participated in the study. Reflective markers were placed on all children in a widely used standard lower extremity marker configuration. All participants walked along a 20-foot walkway at a self-selected speed. The kinematic and kinetic measurements for all children were taken, and the GDI for each subject was calculated. The mean ± standard deviation (SD) GDI of the nine obese children was 88.5 ± 12, which was significantly lower than the GDI of the typically developing children (100 ± 10, p < 0.002). There were no statistically significant correlations between the GDI and the Pediatric Quality of Life (PedsQL) Total score or PedsQL Physical Functioning score. Obese children had a significantly increased anterior pelvic tilt, hip flexion, hip adduction, hip adduction moment, knee flexion, knee valgus, and plantar flexion in stance phase (p < 0.05). While in swing phase, obese children had increased hip adduction and knee varus. The kinematic differences may reveal lower limb mal-alignment in obese children during walking. Overall, the GDI can play a major role in evaluating gait pathology in obese children. Future studies will increase the sample size to further evaluate the correlation between the GDI and functional outcomes.
... Overweight/obesity is thought to be linked to OA development through overload of the joint (especially true for the knee joint, but less for the hip joint) and through low-grade systemic inflammation (all joints, but especially the hand/finger joints). In subjects without knee OA, but with obesity, it is known that weight loss (e.g. through bariatric surgery) reduces the joint stress [29]. Moreover, weight loss as little as 5% significantly reduces the low-grade inflammatory status of the body [30]. ...
This narrative review discusses the potential of prevention of OA in different stages of the disease. The theoretical background for primary prevention (i.e. prevention of occurrence of definite structural or clinical OA in subjects free of the disease) and secondary prevention (i.e. prevention of progression of the disease in subjects with pre-clinical pathological changes to the joint) is provided and evidence for effective strategies is discussed. Since direct evidence for the prevention of OA development and progression is scarce, indirect evidence enhancing our current knowledge on the potential of OA prevention is additionally discussed. Also, implications of preventive strategies for study design and public health are considered. Prevention of OA has great potential, but as deliberated in the current review, there are still large gaps in our current knowledge and the implications of preventive strategies for the development and progression of OA require consideration.
... Stimulation of M3 receptors by acetylcholine leads to smooth muscle contraction [10]. Obesity is a global health problem that affects multiple organs and systems with such conditions as hypertriglyceridemia, type 2 diabetes, hypertension, MetS, coronary heart disease, stroke, cancers, gallstones, female infertility or menstrual irregularities, erectile dysfunction, nonalcoholic fatty liver disease, and osteoarthritis [11][12][13][14][15][16]. There are a wide variety of etiological causes of obesity, such as lack of energy balance, inactive lifestyle, environment, genes and family history, hormonal disturbances, emotional factors, pregnancy, sleep disorders, and, as a new context, a carbohydrate-rich diet. ...
Objectives
We aimed to investigate the effect of a carbohydrate-rich diet on detrusor contractility in rats.
Materials and Methods
Sprague-Dawley rats were randomized into two groups. The control group received regular food and water. The study group received carbohydrate-rich diet for six weeks. The rats' detrusor muscle was isolated for pharmacological and histopathological examinations.
Results
In the control and study groups, mean body weights were 431.5 ± 27.6 g and 528.0 ± 36.2 g, respectively (p < 0.001). Electrical stimulation of the detrusor strips of the control group resulted in gradual contraction. A decreased contractile response was shown in the study group. Acetylcholine in 10-7-10-3 molar concentration produced a decreased contractile response in the study group, compared to the control group (p < 0.01). The study group showed marked subepithelial and intermuscular fibrosis in the bladder.
Conclusion
Carbohydrate-rich diet causes marked subepithelial and extracellular fibrosis and changes in contractility in the detrusor within a six-week period. Changes have higher costs in therapeutic choices and correction of these changes remains difficult. Putting an end to carbohydrate-rich diet would seem to be more cost-effective than dealing with the effects of consuming it in high proportions which should be the national policy worldwide.
... Stimulation of M3 receptors by acetylcholine leads to smooth muscle contraction [10]. Obesity is a global health problem that affects multiple organs and systems with such conditions as hypertriglyceridemia, type 2 diabetes, hypertension, MetS, coronary heart disease, stroke, cancers, gallstones, female infertility or menstrual irregularities, erectile dysfunction, nonalcoholic fatty liver disease, and osteoarthritis [11][12][13][14][15][16]. There are a wide variety of etiological causes of obesity, such as lack of energy balance, inactive lifestyle, environment, genes and family history, hormonal disturbances, emotional factors, pregnancy, sleep disorders, and, as a new context, a carbohydrate-rich diet. ...
Objectives:We aimed to investigate the effect of a carbohydrate-rich diet on detrusor smooth muscle contractility in rats.
Materials and Methods:Sprague-Dawley-rats were randomized into two groups. The control group was received regular food and water. The study group received carbohydrate-rich diet for six weeks. The rats' detrusor muscle was isolated for pharmacological and histopathological examinations.
Results:In the control and study groups, mean body weights were 431.5±27.6 g and 528.0±36.2 g, respectively(p<0.001). Electrical stimulation of the detrusor strips of the control group resulted in gradual contraction. The study group revealed decreased contractile responses compared with the control group. Acetylcholine in 10-7-10-3 molar concentration produced decreased contractile response in the study group, compared to control group(p<0.01). In the study group, histopathological examination showed marked subepithelial and intermuscular fibrosis in the bladder whereas the control group had normal
histology.
Conclusion:Obviously, carbohydrate-rich diet causes marked subepithelial and extracellular fibrosis and changes on contractility in the urinary bladder within six-weeks-period. Changes on higher costs in therapeutic choices and correction of these changes remain difficult. Putting an end to carbohydrate-rich diet would seem to be more cost-effective than dealing with the effects of consuming it in high proportions and should be the national policy worldwide.
... The importance of reducing fat-mass accumulation in obese patients is indisputable; but surprisingly, only a few studies addressing the positive effects of weight loss on changes in walking biomechanics exist. Notwithstanding, massive weight loss produces dramatic reductions in knee forces during walking but when patients walk faster, these favorable reductions become substantially attenuated (Devita et al., 2016). ...
... Fortunately several studies have shown that this is a reversible process and that each unit of weight loss leads to between 2-4 units of force reduction acting within the knee joint [13,14]. However, more recent work by DeVita et al. found that behavioral adaptations following weight loss lead to increased stride length and stride velocity and that as a result the reduction in knee forces was attenuated to a 1:1 ratio [15]. This is still significant and clinicians should encourage overweight patients with knee OA to lose weight regardless for many other health benefits such as a reduction in cardiovascular disease and diabetes prevalence. ...
Knee pain is an increasingly common presentation to general practitioners both in the United Kingdom and worldwide and is thought to be caused by a combination of the obesity epidemic, the ageing population and continuing worldwide population growth. Two distinct aetiologies of knee pain have been described: a bony-type which is usually degenerative in nature; and a ligamentous-type which usually occurs as a result of acute injury but then predisposes to the development of bony-type in later life. There are a wide variety of treatment options available to the clinician: ranging from conservative to major surgery. Total Knee Replacement (TKR) is often the end-point of many causes of knee pain and is used with increasingly frequency. However, there are a wide variety of problems associated with TKR including ongoing pain, patient dissatisfaction and the need for revision surgery. This review aims to demonstrate that TKR should be avoided unless absolutely necessary and also provides the clinician with an overview of the various evidence-based conservative options available to be utilised to improve patient pain and functional knee capabilities.
... [18][19][20][21][22][23][24][25][26] There is also a well-documented effect of obesity on the large joints of the lower limb, with changes in joint biomechanics and biology, often leading to osteoarthritis (OA). [27][28][29][30][31][32][33][34][35][36] Furthermore, obesity has been shown to have a negative effect on postoperative outcomes of many surgical interventions, including those of orthopedics and traumatology. [37][38][39][40][41][42][43] Intra-articular lesions and changes of the knee, including those of the menisci, cruciate ligaments and synovial membrane, have been linked to obesity in many studies. ...
Obesity is currently a global epidemic, often referred to as “globesity”, impacting the life of millions worldwide. A risk factor for many diseases, obesity can also be linked to developing intra-articular lesions of the knee, affecting the menisci, ligaments and cartilage. Furthermore, obesity has been shown to influence the outcome of surgical interventions, including those of the musculoskeletal system. Although many studies addressed the relationship of obesity and joint replacement, articles relating to arthroscopy and obesity, and knee arthroscopy in particular, are a bit scarcer. The majority of data suggest that an increase in BMI leads to a similar increase in the rates of intra- and postoperative complications, and most authors agree that a higher body mass index can influence both the procedure itself and its outcomes, including the subjective results reported by the patients. Still, some studies show different results, especially in patients that are overweight or with low-grade obesity, where the outcomes are comparable to those of the non-obese population. Thus, it can be concluded that obesity is an important patient characteristic that needs to be taken into consideration when planning, performing, and assessing the results of knee arthroscopy.
... Specifically, compared to normal weight adults without knee OA, adults with obese BMI walk more slowly with decreased walking velocities, expend more energy and relative effort when walking 7 , and use more mechanical external work 12 . An overall higher BMI increases loading on the knee [43][44][45] , which exacerbates pain and gait deficits in those with knee OA 46,47 . Consequently, the lifetime risk of knee OA doubles with high body mass (i.e., an obese BMI) 48 . ...
Objective:
Excess weight is a known risk factor for functional limitation and common in adults with knee osteoarthritis (OA). We asked to what extent high waist circumference was linked with developing difficulty with walking speed and distance over 4 years in adults with or at risk of knee OA.
Method:
Using data from the Osteoarthritis Initiative, we employed WHO categories for Body Mass Index (BMI) and waist circumference (small/medium and large). Difficulty with speed was defined by slow gait: < 1.2 m/s during a 20-meter walk, and difficulty with distance was defined by an inability to walk 400 meters. We calculated risk ratios (RR) to examine the likelihood of developing difficulty with distance and speed using obesity and waist circumference as predictors with RRs adjusted for potential confounders (i.e., age, sex, race, education, physical activity, and OA status).
Results:
Participants with obesity and large waists were 2.2 times more likely to have difficulty with speed at 4 years compared to healthy weight and small/medium waisted participants (Adjusted RR 2.2 [95% Confidence interval (CI) 1.6, 3.1], P < .0001). Participants with obesity and a large waist circumference had 2.4 times the risk of developing the inability to walk 400 meters compared with those with a healthy BMI and small/medium waist circumference (Adjusted RR 0.9 [95% CI 1.6, 3.7], P < .0001).
Conclusions:
Waist circumference may be a main risk factor for developing difficulty with speed in adults with or at risk of knee OA.
Objective:
Knee osteoarthritis (KOA) is a common musculoskeletal condition that particularly afflicts women in menopause. The purpose of this review is to describe the pathophysiology and treatment considerations for this subset of the population.
Methods:
Medline/PubMed indexed articles related to the pathophysiology, diagnosis, and management of osteoarthritis were included in this narrative review.
Results and conclusion:
Menopause has a multitude of effects that affect KOA, including hormonal shifts; loss of bone mineral density, muscle mass, and tendon strength; and changes to pain perception. Here, we discuss how a practitioner can assess the factors that are known to worsen KOA symptoms, including postural (spine, pelvic, and knee) alignment and functional muscle strength. The development of an effective exercise program is at the forefront of management. Optimizing other lifestyle factors including nutrition and sleep are particularly important in this patient population. Sleep disturbance from vasomotor symptoms can also increase perception of knee pain, for which pharmacologic options such as gabapentin or duloxetine may be pursued. In total, these interventions have large ramifications in decreasing pain and increasing function through improved range of motion, body composition, and walking speed in women with KOA.
Understanding degeneration of biological and prosthetic knee joints requires knowledge of the in-vivo loading environment during activities of daily living. Musculoskeletal models can estimate medial/lateral tibiofemoral compartment contact forces, yet anthropometric differences between individuals make accurate predictions challenging. We developed a full-body OpenSim musculoskeletal model with a knee joint that incorporates subject-specific tibiofemoral alignment (i.e. knee varus-valgus) and geometry (i.e. contact locations). We tested the accuracy of our model and determined the importance of these subject-specific parameters by comparing estimated to measured medial and lateral contact forces during walking in an individual with an instrumented knee replacement and post-operative genu valgum (6°). The errors in the predictions of the first peak medial and lateral contact force were 12.4% and 11.9%, respectively, for a model with subject-specific tibiofemoral alignment and contact locations determined via radiographic analysis, vs. 63.1% and 42.0%, respectively, for a model with generic parameters. We found that each degree of tibiofemoral alignment deviation altered the first peak medial compartment contact force by 51N (r2=0.99), while each millimeter of medial-lateral translation of the compartment contact point locations altered the first peak medial compartment contact force by 41N (r2=0.99). The model, available at www.simtk.org/home/med-lat-knee/, enables the specification of subject-specific joint alignment and compartment contact locations to more accurately estimate medial and lateral tibiofemoral contact forces in individuals with non-neutral alignment.
Many experimental and computational studies have reported that osteoarthritis in the knee joint affects knee biomechanics, including joint kinematics, joint contact forces, and muscle activities, due to functional restriction and disability. In this study, differences in muscle activities and joint force patterns between knee osteoarthritis (OA) patients and normal subjects during walking were investigated using the inverse dynamic analysis with a lower extremity musculoskeletal model. Extensor/flexor muscle activations and torque ratios and the joint contact forces were compared between the OA and normal groups. The OA patients had higher extensor muscle forces and lateral component of the knee joint force than normal subjects as well as force and torque ratios of extensor and flexor muscles, while the other parameters had little differences. The results explained that OA patients increased the level of antagonistic cocontraction and the adduction moment on the knee joint. The presented findings and technologies provide insight into biomechanical changes in OA patients and can also be used to evaluate the postoperative functional outcomes of the OA treatments.
Net muscle moments (NMMs) have been used as proxy measures of joint loading, but musculoskeletal models can estimate contact forces within joints. The purpose of this study was to use a musculoskeletal model to estimate tibiofemoral forces and to examine the relationship between NMMs and tibiofemoral forces across walking speeds. We collected kinematic, kinetic, and electromyographic data as ten adult participants walked on a dual-belt force-measuring treadmill at 0.75, 1.25, and 1.50 m·s-1. We scaled a musculoskeletal model to each participant and used OpenSim to calculate the NMMs and muscle forces through inverse dynamics and weighted static optimization, respectively. We determined tibiofemoral forces from the vector sum of intersegmental and muscle forces crossing the knee. Estimated tibiofemoral forces increased with walking speed. Peak early-stance compressive tibiofemoral forces increased 52% as walking speed increased from 0.75 to 1.50 m·s-1, while peak knee extension NMMs increased by 168%. During late stance, peak compressive tibiofemoral forces increased by 18% as speed increased. While compressive loads at the knee did not increase in direct proportion to NMMs, faster walking resulted in greater compressive forces during weight acceptance and increased compressive and anterior/posterior tibiofemoral loading rates in addition to a greater abduction NMM.
Muscle loss and fat gain contribute to the disability, pain, and morbidity associated with knee osteoarthritis (OA), and thigh muscle weakness is an independent and modifiable risk factor for it. However, while all published treatment guidelines recommend muscle strengthening exercise to combat loss of muscle mass and strength in knee OA patients, previous strength training studies either used intensities or loads below recommended levels for healthy adults or were generally short, lasting only 6 to 24 weeks. The efficacy of high-intensity strength training in improving OA symptoms, slowing progression, and affecting the underlying mechanisms has not been examined due to the unsubstantiated belief that it might exacerbate symptoms. We hypothesize that in addition to short-term clinical benefits, combining greater duration with high-intensity strength training will alter thigh composition sufficiently to attain long-term reductions in knee-joint forces, lower pain levels, decrease inflammatory cytokines, and slow OA progression.
This is an assessor-blind, randomized controlled trial. The study population consists of 372 older (age >= 55 yrs) ambulatory, community-dwelling persons with: (1) mild-to-moderate medial tibiofemoral OA (Kellgren-Lawrence (KL) = 2-3); (2) knee neutral or varus aligned knee ( -2o valgus <= angle <= 10o varus); (3) 20 kg.m-2 >= BMI <= 45 kg.m-2; and (3) no participation in a formal strength-training program for more than 30 minutes per week within the past 6 months. Participants are randomized to one of 3 groups: high-intensity strength training (75-90% 1Repetition Maximum (1RM)); low-intensity strength training (30-40%1RM); or healthy living education. The primary clinical aim is to compare the interventions' effects on knee pain, and the primary mechanistic aim is to compare their effects on knee-joint compressive forces during walking, a mechanism that affects the OA disease pathway. Secondary aims will compare the interventions' effects on additional clinical measures of disease severity (e.g., function, mobility); disease progression measured by x-ray; thigh muscle and fat volume, measured by computed tomography (CT); components of thigh muscle function, including hip abductor strength and quadriceps strength, and power; additional measures of knee-joint loading; inflammatory and OA biomarkers; and health-related quality of life.
Test-retest reliability for the thigh CT scan was: total thigh volume, intra-class correlation coefficients (ICC) = 0.99; total fat volume, ICC = 0.99, and total muscle volume, ICC = 0.99. ICC for both isokinetic concentric knee flexion and extension strength was 0.93, and for hip-abductor concentric strength was 0.99. The reliability of our 1RM testing was: leg press, ICC = 0.95; leg curl, ICC = 0.99; and leg extension, ICC = 0.98. Results of this trial will provide critically needed guidance for clinicians in a variety of health professions who prescribe and oversee treatment and prevention of OA-related complications. Given the prevalence and impact of OA and the widespread availability of this intervention, assessing the efficacy of optimal strength training has the potential for immediate and vital clinical impact.Trial registration:NCT01489462.
Objective:
People with knee osteoarthritis (OA) are thought to walk with high loads at the knee which are yet to be quantified using modeling techniques that account for subject specific electromyography (EMG) patterns, kinematics and kinetics. The objective was to estimate medial and lateral loading for people with knee OA and controls using an approach that is sensitive to subject specific muscle activation patterns.
Methods:
Sixteen OA and 12 control (C) subjects walked while kinematic, kinetic and EMG data were collected. Muscle forces were calculated using an EMG-Driven model and loading was calculated by balancing the external moments with internal muscle and contact forces.
Results:
OA subjects walked slower and had greater laxity, static and dynamic varus alignment, less flexion and greater knee adduction moment (KAM). Loading [normalized to body weight (BW)] was no different between the groups but OA subjects had greater absolute medial load than controls and maintained a greater %total load on the medial compartment. These patterns were associated with body mass, sagittal and frontal plane moments, static alignment and close to significance for dynamic alignment. Lateral compartment unloading during mid-late stance was observed in 50% of OA subjects.
Conclusions:
Loading for control subjects was similar to data from instrumented prostheses. Knee OA subjects had high medial contact loads in early stance and half of the OA cohort demonstrated lateral compartment lift-off. Results suggest that interventions aimed at reducing BW and dynamic malalignment might be effective in reducing medial compartment loading and establishing normal medio-lateral load sharing patterns.
Background:
Joint pain is a common musculoskeletal complaint of morbidly obese patients that can result in gait abnormalities, perceived mobility limitations, and declining quality of life (QOL). It is not yet known whether weight loss 3 months after bariatric surgery can induce favorable changes in joint pain, gait, perceived mobility, and QOL. Our objectives were to examine whether participants who had undergone bariatric surgery (n = 25; laparoscopic Roux-en-Y gastric bypass or laparoscopic adjustable gastric banding) demonstrate improvements in joint pain, gait (speed, stride/step length, width of base of support, toe angles, single/double support, swing and stance time, functional ambulatory profile), mobility, and QOL by 3 months compared with nonsurgical controls (n = 20). The setting was an orthopedics laboratory at a university hospital in the United States.
Methods:
The present study was a prospective, comparative study. Numeric pain scales (indicating the presence and severity of pain), mobility-related surveys, and the Medical Outcomes Study short-form 36-item questionnaire (SF-36) were completed, and gait and walking speed were assessed at baseline and at month 3.
Results:
The bariatric group lost an average of 21.6 ± 7.7 kg. Significant differences existed between the 2 groups at month 3 in step length, heel to heel base of support, and the percentage of time spent in single and double support during the gait cycle (all P <.05). The severity of low back pain and knee pain decreased by 54% and 34%, respectively, with no changes in the control group (P = .05). The walking speed increased by 15% in the bariatric group (108-123 cm/s; P <.05) but not in the control group. Compared with the control group, fewer bariatric patients perceived limitations with walking and stair climbing by month 3. The bariatric group had a 4.8-cm increase in step length, 2.6% increase in single support time during the gait cycle, and 2.5-cm reduction in the base of support (all P <.05). The SF-36 physical component scores increased 11.8 points in the bariatric group compared with the control group, which showed no improvement by month 3 (P <.0001).
Conclusions:
Improvements in some, but not all, gait parameters, walking speed, and QOL and of perceived functional limitations occur by 3 months after a bariatric procedure.
▪ Objective: To evaluate the effect of weight loss in preventing symptomatic knee osteoarthritis in women.
▪ Design: Cohort analytic study.
▪ Setting: The Framingham Study, based on a sample of a defined population.
▪ Patients: Women who participated in the Framingham Knee Osteoarthritis Study (1983 to 1985): Sixty-four out of 796 women studied had recent-onset symptomatic knee osteoarthritis (knee symptoms plus radiographically confirmed osteoarthritis) were compared with women without disease.
▪ Measurements: Recalled date of symptom onset was used as the incident date of disease. Historical weight was defined as baseline body mass index up to 12 years before symptom onset. Change in body mass index was assessed at several intervals before the current examination. Odds ratios assessing the association between weight change and knee osteoarthritis were adjusted for age, baseline body mass index, history of previous knee injury, habitual physical activity level, occupational physical labor, smoking status, and attained education.
▪ Results: Weight change significantly affected the risk for the development of knee osteoarthritis. For example, a decrease in body mass index of 2 units or more (weight loss, approximately 5.1 kg) over the 10 years before the current examination decreased the odds for developing osteoarthritis by over 50% (odds ratio, 0.46; 95% Cl, 0.24 to 0.86; P = 0.02). Among those women with a high risk for osteoarthritis due to elevated baseline body mass index (> 25), weight loss also decreased the risk (for 2 units of body mass index, odds ratio, 0.41 ; P = 0.02). Weight gain was associated with a slightly increased risk for osteoarthritis, which was not statistically significant.
▪ Conclusion: Weight loss reduces the risk for symptomatic knee osteoarthritis in women.
Osteoarthritis is the most common form of arthritis, affecting millions of people in the United States. It is a complex disease whose etiology bridges biomechanics and biochemistry. Evidence is growing for the role of systemic factors (such as genetics, dietary intake, estrogen use, and bone density) and of local biomechanical factors (such as muscle weakness, obesity, and joint laxity). These risk factors are particularly important in weightbearing joints, and modifying them may present opportunities for prevention of osteoarthritis-related pain and disability. Major advances in management to reduce pain and disability are yielding a panoply of available treatments ranging from nutriceuticals to chondrocyte transplantation, new oral anti-inflammatory medications, and health education. This article is part 1 of a two-part summary of a National Institutes of Health conference. The conference brought together experts on osteoarthritis from diverse backgrounds and provided a multidisciplinary and comprehensive summary of recent advances in the prevention of osteoarthritis onset, progression, and disability. Part 1 focuses on a new understanding of what osteoarthritis is and on risk factors that predispose to disease occurrence. It concludes with a discussion of the impact of osteoarthritis on disability. Ann Intern Med. 2000;133:635-646. www.annals.org For author affiliations and current addresses, see end of text.
The relationship between obesity, weight gain and progression of knee osteoarthritis is well supported, suggesting that excessive joint loading may be a mechanism responsible for cartilage deterioration. Examining the influence of weight gain on joint compressive forces is difficult, as both muscles and ground reaction forces can have a significant impact on the forces experienced during gait. While previous studies have examined the relationship between body weight and knee forces, these studies have used models that were not validated using experimental data. Therefore, the objective of this study was to evaluate the relationship between changes in body weight and changes in knee joint contact forces for an individual's gait pattern using musculoskeletal modeling that is validated against known internal compressive forces. Optimal weighting constants were determined for three subjects to generate valid predictions of knee contact forces (KCFs) using in vivo data collection with instrumented total knee arthroplasty. A total of five simulations per walking trial were generated for each subject, from 80% to 120% body weight in 10% increments, resulting in 50 total simulations. The change in peak KCF with respect to body weight was found to be constant and subject-specific, predominantly determined by the peak force during the baseline condition at 100% body weight. This relationship may be further altered by any change in kinematics or body mass distribution that may occur as a result of a change in body weight or exercise program.
External knee adduction moment has been studied as a surrogate for medial knee contact force. However, it is not known whether adduction moment is a rational measure for predicting medial knee contact force. The aim of this study was to investigate the correlation between knee adduction moment and medial knee contact force in older people, using musculo-skeletal simulation analysis. One hundred and twenty-two healthy older subjects participated in this study. Knee moment and medial knee contact force were calculated based on inverse dynamics analysis of normal walking. Muscle force and joint reaction force were used to determine the medial knee contact force during stance phase. The results showed that the maximum medial knee contact force was moderately correlated to the maximum knee adduction (r = 0.59) as well as the maximum extension moment (r = 0.60). The first peak of medial knee contact force had a significant strong correlation with the first peak of adduction moment and a moderate correlation with the maximum flexion moment. The second peak of medial knee contact force had a significant moderate correlation with both the second peak of adduction and the maximum extension moment. These results implied that the maximum adduction moment value could be used, to some extent, as a measure of the maximum medial knee contact force.
The accuracy of muscle and joint contact forces estimated from dynamic musculoskeletal simulations are dependent upon the experimental kinematic data used as inputs. Subcutaneous adipose tissue makes the measurement of representative kinematics from motion analysis particularly challenging in overweight and obese individuals.
The purpose of this study was to develop an obesity-specific kinematic marker set/methodology that accounted for subcutaneous adiposity, and to determine the effect of using such a methodology to estimate muscle and joint contact forces in moderately obese adults.
Experimental kinematic data from both the obesity-specific methodology, which utilized digitized markers and marker clusters, and a modified Helen Hayes marker methodology were used to generate musculoskeletal simulations of walking in obese and nonobese adults.
Good agreement was found in lower-extremity kinematics, muscle forces, and hip and knee joint contact forces between the two marker set methodologies in the nonobese participants, demonstrating the ability for the obesity-specific marker set/methodology to replicate lower extremity kinematics. In the obese group, marker set methodology had a significant effect on lower-extremity kinematics, muscle forces, and hip and knee joint contact forces, with the Helen Hayes marker set methodology yielding larger muscle and first peak hip and knee contact forces compared to the estimates derived when using the obesity-specific marker set/methodology.
This study demonstrates the need for biomechanists to account for subcutaneous adiposity during kinematic data collection, and proposes a feasible solution that may improve the accuracy of musculoskeletal simulations in overweight and obese people.
Walking is a recommended form of physical activity for obese adults, yet the effects of obesity and walking speed on the biomechanics of walking are not well understood. The purpose of this study was to examine joint kinematics, muscle force requirements and individual muscle contributions to the walking ground reaction forces (GRFs) at two speeds (1.25ms(-1) and 1.50ms(-1)) in obese and nonobese adults. Vasti (VAS), gluteus medius (GMED), gastrocnemius (GAST), and soleus (SOL) forces and their contributions to the GRFs were estimated using three-dimensional musculoskeletal models scaled to the anthropometrics of nine obese (35.0 (3.78kgm(-2))); body mass index mean (SD)) and 10 nonobese (22.1 (1.02kgm(-2))) subjects. The obese individuals walked with a straighter knee in early stance at the faster speed and greater pelvic obliquity during single limb support at both speeds. Absolute force requirements were generally greater in obese vs. nonobese adults, the main exception being VAS, which was similar between groups. At both speeds, lean mass (LM) normalized force output for GMED was greater in the obese group. Obese individuals appear to adopt a gait pattern that reduces VAS force output, especially at speeds greater than their preferred walking velocity. Greater relative GMED force requirements in obese individuals may contribute to altered kinematics and increased risk of musculoskeletal injury/pathology. Our results suggest that obese individuals may have relative weakness of the VAS and hip abductor muscles, specifically GMED, which may act to increase their risk of musculoskeletal injury/pathology during walking, and therefore may benefit from targeted muscle strengthening.
Functional knee braces used during rehabilitation from injury and surgery to the anterior cruciate ligament (ACL) have been reported to provide a strain-shielding effect on the ACL in healthy people while standing, reduce quadriceps electromyography in ACL-deficient individuals, and alter joint torque patterns in people with ACL reconstruction during walking. These results led to the hypothesis that functional knee braces protect a reconstructed ACL during dynamic activity by reducing the anterior shear load applied to the knee. This hypothesis was tested by investigating the effects of a functional knee brace on lower extremity muscle forces and the anteroposterior shear force at the knee joint during the stance phase of walking in people with ACL reconstruction. Ground reactions and sagittal plane video were recorded from 9 ACL-reconstructed individuals as they walked with and without a functional knee brace, and from 10 healthy people without the functional knee brace. Inverse dynamics were used to calculate the net joint torques in the lower extremity during the stance phase. Hamstrings, quadriceps, and gastrocnemius muscle and knee anteroposterior shear force were then predicted with a sagittal-plane mathematical model. Compared to healthy individuals, those with ACL reconstruction walked with 78% more hamstrings impulse and 19% less quadriceps impulse (both p < .05). The functional knee brace produced an additional 43% increase in hamstrings impulse and an additional 13% decrease in quadriceps impulse in the ACL group. Peak anterior knee shear force and anterior impulse were 41% lower and 16% lower in ACL vs. healthy individuals, respectively. The functional knee brace further reduced the peak knee shear force and impulse 28% and 19%, respectively, in the ACL group. It was concluded that a functional knee brace protects a reconstructed ACL during walking by altering muscle forces and reducing the anterior shear force applied to the knee joint.
We determined if slow, uphill walking (0.75 m/s, 6°) reduced tibiofemoral (TF) loading compared to faster, level walking (1.50 m/s) in obese and nonobese adults. We collected kinematic, kinetic, and electromyographic data as 9 moderately obese and 10 nonobese participants walked on a dual-belt instrumented treadmill. We used OpenSim to scale a musculoskeletal model and calculate joint kinematics, kinetics, muscle forces, and TF forces. Compressive TF forces were greater in the obese adults during both speed/grade combinations. During level walking, obese participants walked with a straighter leg than nonobese participants, resulting in early stance vasti muscle forces that were similar in the obese and nonobese participants. Early stance peak compressive TF forces were reduced by 23% in obese (2,352 to 1,811 N) and 35% in nonobese (1,994 to 1,303 N) individuals during slow, uphill walking compared to brisk level walking. Late stance peak TF forces were similar across speeds/grades, but were greater in obese (∼2,900 N) compared to nonobese (∼1,700 N) individuals. Smaller early stance TF loads and loading rates suggest that slow, uphill walking may be appropriate exercise for obese individuals at risk for musculoskeletal pathology or pain. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
Obesity is closely associated with a multitude of musculoskeletal conditions. Many musculoskeletal diseases, including knee osteoarthritis and foot pain, are commonly thought to be related to mechanical overload, and the link to obesity intuitively supports such a notion. Walking is significantly changed in the presence of obesity—changes that are similar to those associated with physical disability among individuals in need of personal assistance in daily life. However, although obesity, osteoarthritis, and other painful musculoskeletal conditions exhibit similar changes in locomotion biomechanics, longitudinal data that confidently demonstrate a causal biomechanical link between obesity and osteoarthritis and plantar fasciitis do not exist and are needed to design better and rational treatments of patients with coexistence of obesity and musculoskeletal disorders.
Importance
Knee osteoarthritis (OA), a common cause of chronic pain and disability, has biomechanical and inflammatory origins and is exacerbated by obesity.Objective
To determine whether a ≥10% reduction in body weight induced by diet, with or without exercise, would improve mechanistic and clinical outcomes more than exercise alone.Design, Setting, and Participants
Single-blind, 18-month, randomized clinical trial at Wake Forest University between July 2006 and April 2011. The diet and exercise interventions were center-based with options for the exercise groups to transition to a home-based program. Participants were 454 overweight and obese older community-dwelling adults (age ≥55 years with body mass index of 27-41) with pain and radiographic knee OA.Interventions
Intensive diet-induced weight loss plus exercise, intensive diet-induced weight loss, or exercise.Main Outcomes and Measures
Mechanistic primary outcomes: knee joint compressive force and plasma IL-6 levels; secondary clinical outcomes: self-reported pain (range, 0-20), function (range, 0-68), mobility, and health-related quality of life (range, 0-100).Results
Three hundred ninety-nine participants (88%) completed the study. Mean weight loss for diet + exercise participants was 10.6 kg (11.4%); for the diet group, 8.9 kg (9.5%); and for the exercise group, 1.8 kg (2.0%). After 18 months, knee compressive forces were lower in diet participants (mean, 2487 N; 95% CI, 2393 to 2581) compared with exercise participants (2687 N; 95% CI, 2590 to 2784, pairwise difference [Δ]exercise vs diet = 200 N; 95% CI, 55 to 345; P = .007). Concentrations of IL-6 were lower in diet + exercise (2.7 pg/mL; 95% CI, 2.5 to 3.0) and diet participants (2.7 pg/mL; 95% CI, 2.4 to 3.0) compared with exercise participants (3.1 pg/mL; 95% CI, 2.9 to 3.4; Δexercise vs diet + exercise = 0.39 pg/mL; 95% CI, −0.03 to 0.81; P = .007; Δexercise vs diet = 0.43 pg/mL; 95% CI, 0.01 to 0.85, P = .006). The diet + exercise group had less pain (3.6; 95% CI, 3.2 to 4.1) and better function (14.1; 95% CI, 12.6 to 15.6) than both the diet group (4.8; 95% CI, 4.3 to 5.2) and exercise group (4.7; 95% CI, 4.2 to 5.1, Δexercise vs diet + exercise = 1.02; 95% CI, 0.33 to 1.71; Ppain = .004; 18.4; 95% CI, 16.9 to 19.9; Δexercise vs diet + exercise, 4.29; 95% CI, 2.07 to 6.50; Pfunction < .001). The diet + exercise group (44.7; 95% CI, 43.4 to 46.0) also had better physical health-related quality of life scores than the exercise group (41.9; 95% CI, 40.5 to 43.2; Δexercise vs diet + exercise = −2.81; 95% CI, −4.76 to −0.86; P = .005).Conclusions and Relevance
Among overweight and obese adults with knee OA, after 18 months, participants in the diet + exercise and diet groups had more weight loss and greater reductions in IL-6 levels than those in the exercise group; those in the diet group had greater reductions in knee compressive force than those in the exercise group.Trial Registration
clinicaltrials.gov Identifier: NCT00381290
Both development and progression of knee osteoarthritis have been associated with the loading of the knee joint during walking. We are, therefore, interested in developing strategies for changing walking biomechanics to offload the knee joint without resorting to surgery. In this study, simulations of human walking were performed using a 2D bipedal forward dynamics model. A simulation generated by minimizing the metabolic cost of transport (CoT) resembled data measured from normal human walking. Three simulations targeted at minimizing the peak axial knee joint contact force instead of the CoT reduced the peak force by 12-25% and increased the CoT by 11-14%. The strategies used by the simulations were (1) reduction in gastrocnemius muscle force, (2) avoidance of knee flexion during stance, and (3) reduced stride length. Reduced gastrocnemius force resulted from a combination of changes in activation and changes in the gastrocnemius contractile component kinematics. The simulations that reduced the peak contact force avoided flexing the knee during stance when knee motion was unrestricted and adopted a shorter stride length when the simulated knee motion was penalized if it deviated from the measured human knee motion. A higher metabolic cost in an offloading gait would be detrimental for covering a long distance without fatigue but beneficial for exercise and weight loss. The predicted changes in the peak axial knee joint contact force from the simulations were consistent with estimates of the joint contact force in a human subject who emulated the predicted kinematics. The results demonstrate the potential of using muscle-actuated forward dynamics simulations to predict novel joint offloading interventions.
Obesity is the primary risk factor for knee osteoarthritis (OA). Greater external knee adduction moments, surrogate measures for medial compartment loading, are present in Obese individuals and may predispose them to knee OA. Laterally wedged insoles decrease the magnitude of the external adduction moment in Obese individuals but it is unknown how they alter the center of pressure on the tibial plateau. A gait analysis was performed on 14 Obese (avg. 29.3 years; BMI range: 30.3-51.6 kg/m(2) ) and 14 lean women (avg. 26.1 years; BMI range: 20.9-24.6 kg/m(2) ) with and without a full-length, wedged insole. Computed joint angles, joint moments, and knee extensor strength values were input into a musculoskeletal model to estimate center of pressure of the contact force on the tibial plateau. Statistical significance was assessed using a two-way ANOVA to compare the main effects of group and insole condition (α = 0.05). The insole resulted in a significant (p < 0.01) lateral shift in the center of pressure location in both the Obese and Control groups (mean: 2.9 ± 0.7 and 1.5 ± 0.7 mm, respectively). The insole also significantly reduced the peak external knee adduction moment 1.88 ± 1.82 N m in the Control group (p < 0.01) and 3.62 ± 3.90 N m in the Obese group (p < 0.01). The results of this study indicate the effects of a prophylactic wedged insole for reducing the magnitude of the load on the knee's medial compartment in Obese women who are at risk for knee OA development. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
Knee osteoarthritis (OA) commonly occurs in the medial compartment of the knee and has been linked to overloading of the medial articular cartilage. Gait modification represents a non-invasive treatment strategy for reducing medial compartment knee force. The purpose of this study was to evaluate the effectiveness of a variety of gait modifications that were expected to alter medial contact force. A single subject implanted with a force-measuring knee replacement walked using nine modified gait patterns, four of which involved different hiking pole configurations. Medial and lateral contact force at 25, 50, and 75% of stance phase, and the average value over all of stance phase (0-100%), were determined for each gait pattern. Changes in medial and lateral contact force values relative to the subject's normal gait pattern were determined by a Kruskal-Wallis test. Apart from early stance (25% of stance), medial contact force was most effectively reduced by walking with long hiking poles and wide pole placement, which significantly reduced medial and lateral contact force during stance phase by up to 34% (at 75% of stance) and 26% (at 50% of stance), respectively. Although this study is based on data from a single subject, the results provide important insight into changes in medial and lateral contact forces through gait modification. The results of this study suggest that an optimal configuration of bilateral hiking poles may significantly reduce both medial and lateral compartment knee forces in individuals with medial knee osteoarthritis. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
This study examines the effects of a radical bariatric surgery-induced weight loss on the gait of obese subjects. We performed a three-dimensional motion analysis of lower limbs, and collected force platform data in the gait laboratory to calculate knee and hip joint moments. Subjects (n=13) performed walking trials in the laboratory before and 8.8 months (SD 4.2) after the surgical procedure at two gait speeds (1.2m/s and 1.5m/s). The average weight loss was 26.7kg (SD 9.2kg), corresponding to 21.5% (SD 6.8%) of the initial weight. We observed a decrease in step width at both gait speeds, but no changes in relative double support or swing time or stride length. A significant decrease was noted in the absolute values of peak knee abductor, peak knee flexor and peak hip extensor moments. However, the moment values normalized by the body weight and height remained unchanged in most cases. Thus, we conclude that weight loss reduces hip and knee joint moments in proportion to the amount of weight lost.
Impairment of the human neuromusculoskeletal system can lead to significant mobility limitations and decreased quality of life. Computational models that accurately represent the musculoskeletal systems of individual patients could be used to explore different treatment options and optimize clinical outcome. The most significant barrier to model-based treatment design is validation of model-based estimates of in vivo contact and muscle forces. This paper introduces an annual "Grand Challenge Competition to Predict In Vivo Knee Loads" based on a series of comprehensive publicly available in vivo data sets for evaluating musculoskeletal model predictions of contact and muscle forces in the knee. The data sets come from patients implanted with force-measuring tibial prostheses. Following a historical review of musculoskeletal modeling methods used for estimating knee muscle and contact forces, we describe the first two data sets used for the first two competitions and summarize four subsequent data sets to be used for future competitions. These data sets include tibial contact force, video motion, ground reaction, muscle EMG, muscle strength, static and dynamic imaging, and implant geometry data. Competition participants create musculoskeletal models to predict tibial contact forces without having access to the corresponding in vivo measurements. These blinded predictions provide an unbiased evaluation of the capabilities and limitations of musculoskeletal modeling methods. The paper concludes with a discussion of how these unique data sets can be used by the musculoskeletal modeling research community to improve the estimation of in vivo muscle and contact forces and ultimately to help make musculoskeletal models clinically useful.
We examined the hypothesis that metabolic surgery-induced massive weight loss causes mass-driven and behavioral adaptations in the kinematics and kinetics of obese gait. Gait analyses were performed at three time points over ∼1 yr in initially morbidly obese (mass: 125.7 kg; body mass index: 43.2 kg/m(2)) but otherwise healthy adults. Ten obese adults lost 27.1% ± 5.1 (34.0 ± 9.4 kg) weight by the first follow-up at 7.0 mo (±0.7) and 6.5 ± 4.2% (8.2 ± 6.0 kg) more by the second follow-up at 12.8 mo (±0.9), with a total weight loss of 33.6 ± 8.1% (42.2 ± 14.1 kg; P = 0.001). Subjects walked at a self-selected and a standard 1.5 m/s speed at the three time points and were also compared with an age- and gender-matched comparison group at the second follow-up. Weight loss increased swing time, stride length, gait speed, hip range of motion, maximal knee flexion, and ankle plantarflexion. Weight loss of 27% led to 3.9% increase in gait speed. An additional 6.5% weight loss led to an additional 7.3% increase in gait speed. Sagittal plane normalized knee torque increased and absolute ankle and frontal plane knee torques decreased after weight loss. We conclude that large weight loss produced mechanical plasticity by modifying ankle and knee torques and gait behavior. There may be a weight loss threshold of 30 kg limiting changes in gait kinematics. Implications for exercise prescription are also discussed.
In a cross sectional study, we investigated the relationships between knee pain and mechanical loading across the knee, as indicated by the external knee adduction moment (KAM) during walking in patients with symptomatic knee OA who were distinguished by different radiographic disease severities.
Data from 137 symptomatic medial knee OA patients were used. Based on Kellgren/Lawrence (K/L) grading, the patients were divided into radiographically less severe (K/L ≤ 2, n=68) or severe (K/L>2, n=69) medial knee OA. Overall knee pain was rated on a 10 cm visual analog scale, and peak KAM and KAM impulses were obtained from gait analyses. Mixed linear regression analyses were performed with KAM variables as the outcome, and pain and disease severity as independent variables, adjusting for age, gender, and walking speed.
In adjusted analyses, less severe patients demonstrated negative relationships between pain intensities and dynamic loading. The severe patient group showed no relationship between pain intensity and peak KAM, and a positive relationship between pain intensity and KAM impulse.
In radiographically less severe knee OA, the negative relationships between pain intensity and dynamic knee joint loading indicate a natural reaction to pain, which will limit the stress on the joint. In contrast, either absent or positive relationships between pain and dynamic loading in severe OA may lead to overuse and accelerated disease progression. These findings may have a large potential interest for strategies of treatment in knee OA.
To evaluate 1-year symptomatic improvement in obese patients with knee osteoarthritis (OA) on an intensive low-energy diet (LED) maintained by frequent consultations with a dietician compared to minimal attention.
The LED programme consisted of group therapy with dietary consultations and two periods of a low-calorie diet of 810 kcal/day during weeks 0-8 and weeks 32-36. The control group only received dietary instruction and attention for 2 h at baseline, and at weeks 8, 32, 36 and 52. The primary end point (total Western Ontario and McMaster Universities (WOMAC) index) was assessed as the mean group difference during and after 1 year.
The study population consisted of 89 patients, 89% women, average age 63 years. After 1 year, mean weight loss in the LED group was -10.9 kg (11%) versus -3.6 kg (4%) in the control group (p<0.0001). There was no difference between the groups in total WOMAC index (p=0.11), although both groups improved. However, the LED intervention resulted in less WOMAC pain (7.7 mm), with a group mean difference of 7.2 mm (95% CI 1.0 to 13.4, p=0.022). After one year 14 (32.8%) responded to LED versus 7 (15.6%) to control, with an absolute benefit of 16.3% (-1.1& to 33.6%, p=0.066).
Continuous reinforcement of a weight loss programme can be successful over a year in obese knee OA patients. Weight loss was statistically reflected only by a reduction in pain. However, the overall clinical benefits of the intervention on health should lead to a strong recommendation of weight loss in this group of patients.
A number of proteins secreted from adipose tissue, known as adipokines, are involved in the inflammatory process. The expression and secretion of adipokines are altered with obesity, leading to a pro-inflammatory state, with an enhanced vascular immune response. Although weight loss reduces inflammation, the time course for these changes during massive weight loss after bariatric surgery is not well described. We examined the changes in the biomarkers of inflammation after laparoscopic Roux-en-Y gastric bypass (RYGB) in morbidly obese individuals in a university hospital.
The fasting levels of plasma inflammatory adipokines, including leptin, adiponectin, C-reactive protein (CRP), interleukin-6, tumor necrosis factor-α (TNF-α), and soluble receptor 1 for TNF-α were measured before surgery (baseline) and 3 weeks, 3 months, and 6 months after surgery in 15 morbidly obese patients who underwent Roux-en-Y gastric bypass without a major complication.
The mean weight loss at 6 months was 25.7% ± 4.5% of the total body weight. The body mass index decreased from a mean of 55.1 ± 6.6 kg/m(2) to 40.5 ± 5.5 kg/m(2). The concentrations of leptin, CRP, and soluble receptor 1 for TNF-α decreased, and the adiponectin levels had increased from the baseline measures by 6 months postoperatively. The baseline and 6-month TNF-α and CRP levels correlated with each other. No other significant associations among the biomarkers were seen.
RYGB reduced the pro-inflammatory biomarkers and increased the anti-inflammatory mediators of obesity, independent of the magnitude of weight loss. The lack of correlations between the changes in biomarkers and weight loss suggests that the driving force behind the changes in the inflammatory markers is multifactorial and needs further investigation to clarify the health changes that occur after RYGB.
To determine the effect of an intensive weight loss program on knee joint loads during walking in obese patients with knee osteoarthritis (OA).
Participants included 157 obese knee OA patients that underwent a 16-week dietary intervention. Three-dimensional gait analyses were performed before and after the intervention at the participants' freely chosen walking speed. Knee joint compression forces, axial impulses, knee flexion angle and frontal and sagittal plane knee moments were calculated to determine the biomechanical effects of the weight loss.
157 subjects (89% of the initial cohort) completed the 16-week intervention. The average weight loss of 13.7 kg (P<.0001) corresponded to 13.5% of the baseline body weight. The weight loss resulted in a 7% reduction in knee joint loading, a 13% lower axial impulse, and a 12% reduction in the internal knee abductor moment (KAM). There were no clear effects on sagittal plane knee moments or peak knee flexion angle. Linear regression analyses adjusted for changes in walking speed showed that for every 1 kg in weight loss, the peak knee load was reduced by 2.2 kg. Thus, every kilo reduction in body weight was related to more than twice the reduction in peak knee force at a given walking speed.
Weight loss is an excellent short-term investment in terms of joint loading for patients with combined obesity and knee OA. The effects of sustained weight loss on disease progression and symptoms in relation to biomechanical factors remain to be shown.
The regional adaptation of knee cartilage morphology to the kinematics of walking has been suggested as an important factor in the evaluation of the consequences of alteration in normal gait leading to osteoarthritis. The purpose of this study was to investigate the association of spatial cartilage thickness distributions of the femur and tibia in the knee to the knee kinematics during walking. Gait data and knee MR images were obtained from 17 healthy volunteers (age 33.2 ± 9.8 years). Cartilage thickness maps were created for the femoral and tibial cartilage. Locations of thickest cartilage in the medial and lateral compartments in the femur and tibia were identified using a numerical method. The flexion-extension (FE) angle associated with the cartilage contact regions on the femur, and the anterior-posterior (AP) translation and internal-external (IE) rotation associated with the cartilage contact regions on the tibia at the heel strike of walking were tested for correlation with the locations of thickest cartilage. The locations of the thickest cartilage had relatively large variation (SD, 8.9°) and was significantly associated with the FE angle at heel strike only in the medial femoral condyle (R(2)=0.41, p<0.01). The natural knee kinematics and contact surface shapes seem to affect the functional adaptation of knee articular cartilage morphology. The sensitivity of cartilage morphology to kinematics at the knee during walking suggests that regional cartilage thickness variations are influenced by both loading and the number of loading cycles. Thus walking is an important consideration in the analysis of the morphological variations of articular cartilage, since it is the dominant cyclic activity of daily living. The sensitivity of cartilage morphology to gait kinematics is also important in understanding the etiology and pathomechanics of osteoarthritis.
The aim of this study was to examine the effects of high weight loss on knee joint loads during walking in participants with knee osteoarthritis (OA).
Data were obtained from a subset of participants enrolled in the Arthritis, Diet, and Activity Promotion Trial (ADAPT). Complete baseline and 18-month follow-up data were obtained on 76 sedentary, overweight or obese older adults with radiographic knee OA. Three-dimensional gait analysis was used to calculate knee joint forces and moments. The cohort was divided into high (>5%), low (<5%), and no (0% or gain) weight loss groups.
From baseline body weight, the high weight loss group lost an average of 10.2%, the low weight loss group lost an average of 2.7%, and the no weight loss group gained 1.5%. Adjusted 18-month outcome data revealed lower maximum knee compressive forces with greater weight loss (P=0.05). The difference in compressive forces between the high weight loss and no weight loss groups was due primarily to lower hamstring forces (P=0.04). Quadriceps forces were similar between the groups at 18-month follow-up. There was no difference between the groups in 18-month joint space width or Kellgren-Lawrence scores.
These results suggest that a 10% weight loss in an overweight and obese osteoarthritic population elicits positive changes in the mechanical pathway to knee OA by having lower knee joint compressive loads during walking compared to low and no weight loss groups. The difference in compressive forces was due, in large part, to reductions in hamstring co-contraction during the initial portion of the stance phase.
Muscles are significant contributors to the high joint forces developed in the knee during human walking. Not only do muscles contribute to the knee joint forces by acting to compress the joint, but they also develop joint forces indirectly through their contributions to the ground reaction forces via dynamic coupling. Thus, muscles can have significant contributions to forces at joints they do not span. However, few studies have investigated how the major lower-limb muscles contribute to the knee joint contact forces during walking. The goal of this study was to use a muscle-actuated forward dynamics simulation of walking to identify how individual muscles contribute to the axial tibio-femoral joint force. The simulation results showed that the vastii muscles are the primary contributors to the axial joint force in early stance while the gastrocnemius is the primary contributor in late stance. The tibio-femoral joint force generated by these muscles was at times greater than the muscle forces themselves. Muscles that do not cross the knee joint (e.g., the gluteus maximus and soleus) also have significant contributions to the tibio-femoral joint force through their contributions to the ground reaction forces. Further, small changes in walking kinematics (e.g., knee flexion angle) can have a significant effect on the magnitude of the knee joint forces. Thus, altering walking mechanics and muscle coordination patterns to utilize muscle groups that perform the same biomechanical function, yet contribute less to the knee joint forces may be an effective way to reduce knee joint loading during walking.
In using musculoskeletal models, researchers can calculate muscle forces, and subsequently joint contact forces, providing insight into joint loading and the progression of such diseases as osteoarthritis (OA). The purpose of this study was to estimate the knee contact force (KCF) in patients with varying degrees of OA severity using muscle forces and joint reaction forces derived from OpenSim. Walking data was obtained from healthy individuals (n=14) and those with moderate (n=10) and severe knee OA (n=2). For each subject, we generated 3D, muscle-actuated, forward dynamic simulations of the walking trials. Muscle forces that reproduced each subject's gait were calculated. KCFs were then calculated using the vector sum of the muscle forces and joint reaction forces along the longitudinal axis of the femur. Moderate OA subjects exhibited a similar KCF pattern to healthy subjects, with lower second peaks (p=0.021). Although subjects with severe OA had similar initial peak KCF to healthy and moderate OA subjects (more than 4 times BW), the pattern of the KCF was very different between groups. After an initial peak, subjects with severe OA continually unloaded the joint, whereas healthy and moderate OA subjects reloaded the knee during late stance. In subjects with symmetric OA grades, there appears to be differences in loading between OA severities. Similar initial peaks of KCF imply that reduction of peak KCF may not be a compensatory strategy for OA patients; however, reducing duration of high magnitude loads may be employed.
This review describes how computational modeling can be combined with noninvasive gait measurements to describe and explain muscle and joint function in human locomotion. Five muscles--the gluteus maximus, gluteus medius, vasti, soleus, and gastrocnemius--contribute most significantly to the accelerations of the center of mass in the vertical, fore-aft, and medio-lateral directions when humans walk and run at their preferred speeds. Humans choose to switch from a walk to a run at speeds near 2 m s(-1) to enhance the biomechanical performance of the ankle plantarflexors and to improve coordination of the knee and ankle muscles during stance. Muscles that do not span a joint can contribute to the contact force transmitted by that joint and therefore affect its stability. In walking, for example, uniarticular muscles that cross the hip and ankle act to create the adduction moment at the knee, thereby contributing to the contact force present in the medial compartment.
Medial knee osteoarthritis (OA) is characterized by pain and associated with abnormal knee moments during walking. The relationship between knee OA pain and gait changes remains to be clarified, and a better understanding of this link could advance the treatment and prevention of disease progression. This study investigated changes in knee moments during walking following experimental knee pain in healthy volunteers, and whether these changes replicated the joint moments observed in medial knee OA patients.
In a crossover study, 34 healthy subjects were tested on 3 different days; gait analyses were conducted before, during, and after pain induced by hypertonic saline injections (0.75 ml) into the infrapatellar fat pad. Isotonic saline and sham injections were used as control conditions. Peak moments in frontal and sagittal planes were analyzed. The results were compared with data from 161 medial knee OA patients. The patients were divided into less severe OA and severe OA categories, which was based on radiographic disease severity of the medial compartment.
Experimental knee pain led to reduced peak moments in the frontal and sagittal planes in the healthy subjects, which were similar to the patterns observed in less severe OA patients while walking at the same speed.
In healthy subjects, pain was associated with reductions in knee joint moments during walking in a manner similar to less severe knee OA patients. The experimental model may be used to study mechanically-driven knee OA progression and preventive measures against abnormal joint loading in knee OA.
This study was performed to investigate whether changes in biomechanical parameters of walking explain the reduction in net metabolic cost after weight loss in obese adolescents.
Body composition and metabolic and mechanical energy costs of walking at 1.25 m·s(-1) were assessed in 16 obese adolescents before and after a weight loss. Center of mass (COM) and foot accelerations were measured using two inertial sensors and integrated twice to determine COM and foot velocities and displacements. Potential and kinetic energy fluctuations of the COM and the external mechanical work were calculated. Lateral leg swing was calculated from foot displacements.
As expected, the decrease in net metabolic cost was greater, which would have been expected on the basis of the amount of weight loss. The smaller lateral leg swing after weight loss did not explain part of the decrease in net metabolic cost. The reduced body mass required less leg muscle work to raise and accelerate the COM as well as to support body weight. The decrease in body mass seems also associated with a lesser leg muscle work required to raise the COM because of smaller vertical motions. As a result of the inverted pendulum mechanism, the decrease in vertical motions (hence in potential energy fluctuations) was probably related to the decrease in mediolateral kinetic energy fluctuations. Moreover, the lesser amount of fat mass in the gynoid region seems related to the decrease in net metabolic cost of walking.
The reduction in net metabolic cost of walking after weight loss in weight-reduced adolescents is associated with changes in the biomechanical parameters of walking.
Obesity is the primary modifiable risk factor for knee osteoarthritis. The goal of this study was to develop a walking protocol for obese individuals that supported weight loss while minimizing biomechanical risk factors for knee osteoarthritis. We tested the hypotheses that walking with short, quick strides at a preferred walking speed requires more energy expenditure in obese women and reduces biomechanical risk factors for knee osteoarthritis at foot-ground impact relative to walking at the preferred stride length.
Ten obese (BMI=33.09(4.22)kg/m(2)) and 10 healthy-weight (BMI=22.66(0.86)kg/m(2)) women volunteered. V O(2) was measured while subjects walked on a treadmill at their preferred walking speed at a preferred stride length and a 15% shortened stride length (increased stride frequency). Peak impact shock, peak external knee adduction moment, and knee adduction angular impulse were measured during the two gait conditions.
Decreasing stride length 15% significantly increased metabolic cost by 4.6% (P<0.01; effect size=0.24) and decreased the adduction angular impulse (P=0.046; effect size=0.203), but did not significantly affect the adduction moment (P=0.196; effect size=0.100) or impact shock (P=0.698; effect size=0.605).
The small, but significant, increase in metabolic cost when walking with short, quick steps may be beneficial for weight reduction or maintenance in obese populations. The results of this study suggest that a 15% decrease in stride length is not sufficient to decrease the peak values of two of the biomechanical variables that may predispose obese women to knee osteoarthritis but does elicit benefits over the course of a stride.
To examine the degree to which 2 commonly used measures of pain and disability, the Arthritis Impact Measurement Scales (AIMS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), relate to objective gait measurements.
A descriptive study of the influence of self-reported pain and perceived functional impairment on gait mechanics in osteoarthritic adults.
A university clinical research laboratory.
Overweight/obese adults with radiographic knee osteoarthritis (OA) as well as pain and disability associated with the disease (N=179).
Not applicable.
The AIMS and WOMAC were administered to determine self-report measures of pain and disability. Speed, stride length, support time, knee angle, and peak vertical force (PVF) were determined from 3-dimensional kinematic and kinetic data collected on subjects walking at self-selected normal and fast speeds. Anthropometric data and radiographic levels of OA were also collected.
Pearson correlation analysis showed that the AIMS physical disability score was inversely correlated with speed, stride length, and knee range of motion at both speeds and PVF at the fast speed. The WOMAC function score was inversely correlated with speed and stride length at both speeds and with PVF at fast speed. The WOMAC pain score was inversely correlated with speed and PVF at the fast speed. Regression analysis revealed that the AIMS physical disability score and body mass index accounted for the greatest variation in speed at the normal speed. Overall, AIMS physical disability and WOMAC function explained a larger proportion of variance in gait mechanics than radiographic measures of OA disease severity.
Taken together, the results suggest that the AIMS physical disability and WOMAC function scores are associated with some important measures of gait impairment.
Large knee adduction moments during gait have been implicated as a mechanical factor related to the progression and severity of tibiofemoral osteoarthritis and it has been proposed that these moments increase the load on the medial compartment of the knee joint. However, this mechanism cannot be validated without taking into account the internal forces and moments generated by the muscles and ligaments, which cannot be easily measured. Previous musculoskeletal models suggest that the medial compartment of the tibiofemoral joint bears the majority of the tibiofemoral load, with the lateral compartment unloaded at times during stance. Yet these models did not utilise explicitly measured muscle activation patterns and measurements from an instrumented prosthesis which do not portray lateral compartment unloading. This paper utilised an EMG-driven model to estimate muscle forces and knee joint contact forces during healthy gait. Results indicate that while the medial compartment does bear the majority of the load during stance, muscles provide sufficient stability to counter the tendency of the external adduction moment to unload the lateral compartment. This stability was predominantly provided by the quadriceps, hamstrings, and gastrocnemii muscles, although the contribution from the tensor fascia latae was also significant. Lateral compartment unloading was not predicted by the EMG-driven model, suggesting that muscle activity patterns provide useful input to estimate muscle and joint contact forces.
Walking is the most common type of physical activity prescribed for the treatment of obesity. The net metabolic rate during level walking (W/kg) is approximately 10% greater in obese vs. normal weight adults. External mechanical work (W(ext)) is one of the primary determinants of the metabolic cost of walking, but the effects of obesity on W(ext) have not been clearly established. The purpose of this study was to compare W(ext) between obese and normal weight adults across a range of walking speeds. We hypothesized that W(ext) (J/step) would be greater in obese adults but W(ext) normalized to body mass would be similar in obese and normal weight adults. We collected right leg three-dimensional ground reaction forces (GRF) while twenty adults (10 obese, BMI=35.6 kg/m(2) and 10 normal weight, BMI=22.1 kg/m(2)) walked on a level, dual-belt force measuring treadmill at six speeds (0.50-1.75 m/s). We used the individual limb method (ILM) to calculate external work done on the center of mass. Absolute W(ext) (J/step) was greater in obese vs. normal weight adults at each walking speed, but relative W(ext) (J/step/kg) was similar between the groups. Step frequencies were not different. These results suggest that W(ext) is not responsible for the greater metabolic cost of walking (W/kg) in moderately obese adults.
To compare frontal plane lower extremity biomechanics during walking in adolescent boys who were overweight (OW) versus healthy weight (HW).
Fourteen boys (7 considered HW, body mass index for age <85th percentile; age 10.8 +/- 0.7 years; 7 considered OW, body mass index for age >95th percentile; age 12.0 +/- 0.7 years) participated. Three-dimensional kinematic data were collected during walking at self-selected speeds. Group means were compared using Student's t tests (alpha = 0.05).
Significant differences were found in timing of rearfoot motions and moments, amplitude of knee motion peaks, timing of knee moment peaks, and timing and amplitudes of peak hip motion and moments.
Boys who were OW collapsed into hip adduction and knee valgus during stance and attempted to compensate with rearfoot inversion. Observed differences in frontal plane kinematics during walking suggest that boys who are OW have increased risk of lower extremity musculoskeletal injuries and dysfunction.
Musculoskeletal modeling and optimization theory are often used to determine muscle forces in vivo. However, convincing quantitative evaluation of these predictions has been limited to date. The present study evaluated model predictions of knee muscle forces during walking using in vivo measurements of joint contact loading acquired from an instrumented implant. Joint motion, ground reaction force, and tibial contact force data were recorded simultaneously from a single subject walking at slow, normal, and fast speeds. The body was modeled as an 8-segment, 21-degree-of-freedom articulated linkage, actuated by 58 muscles. Joint moments obtained from inverse dynamics were decomposed into leg-muscle forces by solving an optimization problem that minimized the sum of the squares of the muscle activations. The predicted knee muscle forces were input into a 3D knee implant contact model to calculate tibial contact forces. Calculated and measured tibial contact forces were in good agreement for all three walking speeds. The average RMS errors for the medial, lateral, and total contact forces over the entire gait cycle and across all trials were 140 +/- 40 N, 115 +/- 32 N, and 183 +/- 45 N, respectively. Muscle coordination predicted by the model was also consistent with EMG measurements reported for normal walking. The combined experimental and modeling approach used in this study provides a quantitative framework for evaluating model predictions of muscle forces in human movement.
Obesity is a risk factor for impaired physical function and disability, with the degree of impairment most compromised in extreme obesity. Mild-to-moderate weight loss has been shown to improve function in older adults. The impact of laparoscopic Roux-en-Y gastric bypass surgery on weight loss and physical function in morbidly obese individuals was assessed.
This longitudinal, observational study followed up 28 morbidly obese men and women (body mass index > or = 40.0 kg/m(2)) for 12 months after laparoscopic Roux-en-Y gastric bypass. Physical function (self-report using the Fitness Arthritis and Seniors Trial disability questionnaire; performance tasks using the Short Physical Performance Battery and a lateral mobility task); strength (maximal isometric knee torque); and body composition measured using bioelectrical impedance were determined before surgery (baseline) and at 3 weeks, 3 months, 6 months, and 12 months after surgery.
The 12-month weight loss was 34.2% (excess weight loss 59.8%), with a mean fat mass loss of 46 kg and a loss of fat free mass of 6.6 kg. The performance tasks and self-reported questionnaire scores had improved by 3 months after surgery compared with baseline, with selected measures showing less impairment and disability in as few as 3 weeks after surgery. Muscle quality, as measured using the maximal torque per kilogram body weight, was greater at 6 months than at baseline.
The results of our study have shown that in morbidly obese individuals with a high risk of mobility impairments, surgical procedures to reduce body weight increase mobility and improve performance of daily activities in as few as 3 weeks after gastric bypass surgery.
While knee osteoarthritis has been shown to affect a multitude of kinematic, kinetic and temporo-spatial gait parameters, few investigations have examined the effect of increasing levels of radiographic osteoarthritis severity on these gait parameters. Fewer still have investigated the effect of walking speed on gait variables in persons with knee osteoarthritis. The objective of this study was to investigate the influence of walking speed on biomechanical variables associated with joint loading in persons with varying severities of medial compartment knee osteoarthritis.
Twenty-one persons with moderate osteoarthritis (Kellgren-Lawrence score 2-3) and 13 persons with severe osteoarthritis (Kellgren-Lawrence score of 4) participated. Twenty-two persons without knee pain or radiographic evidence of arthritis comprised a healthy control group. Sagittal plane kinetics, knee adduction moment, sagittal plane knee excursion, ground reaction forces and knee joint reaction forces were calculated from three-dimensional motion analysis at 1.0m/s, self-selected and fastest tolerable walking speeds. Differences were analyzed using multivariate analysis of variance and multivariate analysis of covariance with speed as a covariate.
Persons with knee osteoarthritis showed significantly lower knee and ankle joint moments, ground reaction forces, knee reaction force and knee excursion when walking at freely chosen speeds. When differences in walking speed were accounted for in the analysis, the only difference found at all conditions was decreased knee joint excursion.
Compared to a healthy control group, persons with knee OA demonstrate differences in joint kinetics and kinematics. Except for knee excursion, these differences in gait parameters appear to be a result of slower freely chosen walking speeds rather than a result of disease progression.
To examine whether obesity increases the risk of progression of knee osteoarthritis (OA).
We used data from the Multicenter Osteoarthritis Study, a longitudinal study of persons with or at high risk of knee OA. OA was characterized at baseline and 30 months using posteroanterior fixed-flexion radiographs and Kellgren/Lawrence (K/L) grading, with alignment assessed on full-extremity films. In knees with OA at baseline (K/L grade 2 or 3), progression was defined as tibiofemoral joint space narrowing on the 30-month radiograph. In knees without OA at baseline (K/L grade 0 or 1), incident OA was defined as the development of radiographic OA at 30 months. Body mass index (BMI) at baseline was classified as normal (<25 kg/m(2)), overweight (25-<30 kg/m(2)), obese (30-<35 kg/m(2)), and very obese (>or=35 kg/m(2)). The risk of progression was tested in all knees and in subgroups categorized according to alignment. Analyses were adjusted for age, sex, knee injury, and bone density.
Among the 2,623 subjects (5,159 knees), 60% were women, and the mean +/- SD age was 62.4 +/- 8.0 years. More than 80% of subjects were overweight or obese. At baseline, 36.4% of knees had tibiofemoral OA, and of those, only one-third were neutrally aligned. Compared with subjects with a normal BMI, those who were obese or very obese were at an increased risk of incident OA (relative risk 2.4 and 3.2, respectively [P for trend < 0.001]); this risk extended to knees from all alignment groups. Among knees with OA at baseline, there was no overall association between a high BMI and the risk of OA progression; however, an increased risk of progression was observed among knees with neutral but not varus alignment. The effect of obesity was intermediate in those with valgus alignment.
Although obesity was a risk factor for incident knee OA, we observed no overall relationship between obesity and the progression of knee OA. Obesity was not associated with OA progression in knees with varus alignment; however, it did increase the risk of progression in knees with neutral or valgus alignment. Therefore, weight loss may not be effective in preventing progression of structural damage in OA knees with varus alignment.
The response of healthy and diseased cartilage of the knee to the mechanics of walking is examined, with the goal of providing insight into the relationship between the kinematics and kinetics of the knee during walking and the maintenance of cartilage health. The combination of information from three-dimensional thickness models of cartilage derived from magnetic resonance imaging and the analysis of the interaction between load at the knee and kinematic changes during walking associated with loss of the anterior cruciate ligament demonstrated the importance of considering walking mechanics as an important factor in the initiation and progression of osteoarthritis. In particular, this material suggests that knee cartilage becomes conditioned to loading and to the large number of repetitive cycles of loading that occur during walking and that healthy cartilage homeostasis is maintained as long as there are no changes to the normal patterns of locomotion, the structure of the knee joint, or cartilage biology. Thus, there is the potential for a degenerative pathway to be initiated when a condition such as anterior cruciate ligament injury causes the repetitive loading during walking to shift to a new location. The sensitivity of cartilage to the kinematic changes is illustrated with the anterior cruciate ligament-deficient knee and the regional variations in cartilage morphology. The material presented here supports the conclusion that individual variations in the range of loading and kinematics at the knee during walking can have a profound influence on the initiation and progression of osteoarthritis of the knee.
The mechanisms by which obesity affects osteoarthritis (OA) are of great concern to osteoarthritis researchers and clinicians who manage this disease. Inflammation and joint loads are pathways commonly believed to cause or to exacerbate the disease process. This article reviews the physiologic and mechanical consequences of obesity in older adults who have knee OA, the effects of long-term exercise and weight-loss interventions, the most effective nonpharmacologic treatments for obesity, and the usefulness and feasibility of translating these results to clinical practice.
To evaluate the effect of weight loss in preventing symptomatic knee osteoarthritis in women.
Cohort analytic study.
The Framingham Study, based on a sample of a defined population.
Women who participated in the Framingham Knee Osteoarthritis Study (1983 to 1985): Sixty-four out of 796 women studied had recent-onset symptomatic knee osteoarthritis (knee symptoms plus radiographically confirmed osteoarthritis) were compared with women without disease.
Recalled date of symptom onset was used as the incident date of disease. Historical weight was defined as baseline body mass index up to 12 years before symptom onset. Change in body mass index was assessed at several intervals before the current examination. Odds ratios assessing the association between weight change and knee osteoarthritis were adjusted for age, baseline body mass index, history of previous knee injury, habitual physical activity level, occupational physical labor, smoking status, and attained education.
Weight change significantly affected the risk for the development of knee osteoarthritis. For example, a decrease in body mass index of 2 units or more (weight loss, approximately 5,1 kg) over the 10 years before the current examination decreased the odds for developing osteoarthritis by over 50% (odds ratio, 0.46; 95% Cl, 0.24 to 0.86; P = 0.02). Among those women with a high risk for osteoarthritis due to elevated baseline body mass index (greater than or equal to 25), weight loss also decreased the risk (for 2 units of body mass index, odds ratio, 0.41; P = 0.02). Weight gain was associated with a slightly increased risk for osteoarthritis, which was not statistically significant.
Weight loss reduces the risk for symptomatic knee osteoarthritis in women.
The gait of normal subjects and patients with varus deformities at the knee was studied by analyzing the interaction between the dynamic (muscular) and passive (ligamentous) restraints affecting lateral stability of the knee. A statistically determinant model predicted that the midstance-phase adducting moment during normal gait would cause lateral knee joint opening if either antagonistic muscle force and/or pretension in the lateral soft tissues were not present at the knee. The patient group tended to compensate for a high midstance-phase adducting moment by walking with a style of gait that demanded more muscle force (greater flexion-extension moments). This walking style reduced the chance of lateral joint opening. It can be speculated that this style of gait would help to maintain equilibrium at the knee. The higher muscle force would aid in resisting the adducting moment, keeping the joint closed laterally and thus increasing the stability of the knee.
To determine whether obesity preceded knee osteoarthritis and was thus a possible cause.
Cohort study with weight and other important variables measured in 1948 to 1951 (mean age of subjects, 37 years) and knee arthritis evaluated in 1983 to 1985 (mean age of subjects, 73 years).
Population-based participants; a subset (n = 1420) of the Framingham Heart Study cohort.
For those subjects in the Framingham Study having knee radiographs taken as part of the 18th biennial examination (1983 to 1985), we examined Metropolitan Relative Weight, a measure of weight adjusted for height at the onset of the study (1948 to 1951). Relative risks were computed as the cumulative incidence rate of radiographic knee osteoarthritis in the heaviest weight groups at examination 1 divided by the cumulative rate in the lightest 60% weight groups at examination 1. Relative risks were adjusted for age, physical activity level, and uric acid level.
In 1983 to 1985, 468 subjects (33%) had radiographic knee osteoarthritis. For men, the risk of knee osteoarthritis was increased in those in the heaviest quintile of weight at examination 1 compared with those in the lightest three quintiles (age-adjusted relative risk, 1.51; 95% confidence interval [CI], 1.14 to 1.98); risk was not increased for those in the second heaviest quintile (relative risk, 1.0). The association between weight and knee osteoarthritis was stronger in women than in men; for women in the most overweight quintile at examination 1, relative risk was 2.07 (95% CI, 1.67 to 2.55), and for those in the second heaviest group, relative risk was 1.44 (95% CI, 1.11 to 1.86). This link between obesity and subsequent osteoarthritis persisted after controlling for serum uric acid level and physical activity level, and was strongest for persons with severest radiographic disease. Obesity at examination 1 was associated with the risk of developing both symptomatic and asymptomatic osteoarthritis.
These results and other corroborative cross-sectional data show that obesity or as yet unknown factors associated with obesity cause knee osteoarthritis.
The objective of this study was to assess the association between obesity and osteoarthritis (OA) of the knee, hip, and hand. OA patterns were studied in 809 patients with knee or hip joint replacement due to OA. Patients with OA were categorized as having bilateral or generalized OA according to the presence of radiographic OA in the contralateral joint or different finger joints, and as normal weight, overweight, or obese according to their body mass index (BMI). Odds ratios (OR) and 95% confidence intervals (CI) for relative weight and OA patterns were estimated with multivariable logistic regression. Eighty-five percent of participants had bilateral OA, 26% had generalized OA, and 31% were obese. Obesity (BMI >/= 30 kg/m(2); OR = 8.1; 95% CI: 2.4-28) and overweight (BMI >/= 25 kg/m(2); OR = 5.9; 95% CI: 2.0-18) were strongly associated with bilateral knee OA. No association between obesity and bilateral hip OA (OR = 0.7; 95% CI: 0.3-1.7) nor generalized OA (OR = 1.1; 95% CI: 0.6-2.1) was observed. Obesity seems to be a mechanical rather than a systemic risk factor for OA with the knee joint being especially susceptible.