Article
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Total hip arthroplasty is a successful surgical procedure to treat patients with hip osteoarthritis. Clinicians use different questionnaires to evaluate these patients. Gait velocity and these questionnaires; usually show significant improvement after total hip arthroplasty. This clinical evaluation does, however, not provide objective, quantifiable information about the movement patterns underlying the functional capacity, which is clinically important and can currently only be obtained in a gait laboratory. There is a need to improve patient instructions and to quantify the rehabilitation process. The sit to stand (STS) movement is an objective performance-based task, whose assessment is related with the evaluation of functional recovery. Twenty two patients with hip osteoarthritis participated in this study. For each patient, validated questionnaires were administered and gait velocity was measured. Time, ground reaction forces and lower limb asymmetry parameters were calculated using the Instrumented Force Shoes (IFS) during STS movement with and without armrest. Significant inter-limb asymmetry was observed. No correlation was found between any parameter and gait velocity and questionnaires outcomes. Significant differences in time and force parameters between with/without armrest were found. Concluding, inter-limb asymmetry can be evaluated with the IFS supplying important additional information not represented by gait velocity and questionnaires usually used.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Both measurements, before [34,35] and after THA, included 2 functional mobility tasks, walking and a Sit-to-Stand test, while the subject was wearing instrumented shoes. ...
... Subjects were seated in a chair with armrests as it is described in a pre-surgery study with this patient group [35]. The chair height and depth were adjusted in a way that the knee angles were 90 degrees in a seated position. ...
... Vertical ground reaction forces during walking and sit to stand test before and after THA for one representative subject are plotted in Figure 2. Among all possible IS parameters, the following parameters were selected based on the previous studies of presurgery assessment with these patients [34,35]. ...
Article
Full-text available
Total hip arthroplasty is a successful surgical treatment in patients with osteoarthritis of the hip. Different questionnaires are used by the clinicians to assess functional capacity and the patient's pain, despite these questionnaires are known to be subjective. Furthermore, many studies agree that kinematic and kinetic parameters are crucial to evaluate and to provide useful information about the patient's evolution for clinicians and rehabilitation specialists. However, these quantities can currently only be obtained in a fully equipped gait laboratory. Instrumented shoes can quantify gait velocity, kinetic, kinematic and symmetry parameters. The aim of this study was to investigate whether the instrumented shoes is a sufficiently sensitive instrument to show differences in mobility performance before and after total hip arthroplasty. In this study, patients undergoing total hip arthroplasty were measured before and 6-8 months after total hip arthroplasty. Both measurement sessions include 2 functional mobility tasks while the subject was wearing instrumented shoes. Before each measurement the Harris Hip Score and the Traditional Western Ontario and McMaster Universities osteoarthritis index were administered as well. The stance time and the average vertical ground reaction force measured with the instrumented shoes during walking, and their symmetry index, showed significant differences before and after total hip arthroplasty. However, the data obtained with the sit to stand test did not reveal this improvement after surgery. Our results show that inter-limb asymmetry during a walking activity can be evaluated with the instrumented shoes before and after total hip arthroplasty in an outpatient clinical setting.
... Sit-to-stand (STS), the act of rising from a chair is regarded as an important movement to use in functional assessments [1,2] because it is a prerequisite of many activities in daily living [3][4][5][6]. With the elderly [7] and mobility-limited patients (e.g., patients with hemiparesis [8,9], hip arthroplasty [6,10,11], hip fracture [12]), their STS becomes slow and accompanies asymmetric weight-bearing (asymmetric STS) due to the reduction of unilateral muscle strength in the lower limbs [9,13]. Especially, asymmetric STS relates to a decline in functional performance [13] and a higher fall risk [14]. ...
Article
Full-text available
To provide effective diagnosis and rehabilitation, the evaluation of joint moments during sit-to-stand is essential. The conventional systems for the evaluation, which use motion capture cameras, are quite accurate. However, the systems are not widely used in clinics due to their high cost, inconvenience, and the fact they require lots of space. To solve these problems, some studies have attempted to use inertial sensors only, but they were still inconvenient and inaccurate with asymmetric weight-bearing. We propose a novel joint moment estimation system that can evaluate both symmetric and asymmetric sit-to-stands. To make a simplified system, the proposal is based on a kinematic model that estimates segment angles using a single inertial sensor attached to the shank and a force plate. The system was evaluated with 16 healthy people through symmetric and asymmetric weight-bearing sit-to-stand. The results showed that the proposed system (1) has good accuracy in estimating joint moments (root mean square error < 0.110 Nm/kg) with high correlation (correlation coefficient > 0.99) and (2) is clinically relevant due to its simplicity and applicability of asymmetric sit-to-stand.
... Asymmetrical weight bearing is common in individuals with unilateral hip osteoarthritis (OA), before and after total hip arthroplasty (THA). Before and after THA, individuals use compensatory strategies to complete common activities of daily living, such as the sit-to-stand task (STS) (Abujaber et al., 2015a;Boonstra et al., 2011;Eitzen et al., 2014;Martinez-Ramirez et al., 2014;Talis et al., 2007;Talis et al., 2008). During the STS, these individuals rely on the non-affected limb to complete the activity, which results in 17-22% less vertical ground reaction force under the affected limb (Boonstra et al., 2011;Talis et al., 2008) and asymmetrical hip and knee joint moments that are lower on the affected side (Eitzen et al., 2014;Lamontagne et al., 2012;Varin, 2011). ...
Article
Background Weight-bearing asymmetry is common in individuals with hip osteoarthritis and after total hip arthroplasty. Including symmetry training to the rehabilitation programs may normalize movement strategies during dynamic tasks. The purpose of this study was to evaluate the immediate influences of real-time visual feedback of weight distribution on the interlimb movement symmetry during the sit-to-stand task, before and after total hip arthroplasty, and to determine whether physical impairments affect the response to visual feedback. Methods Subjects before and after total hip arthroplasty participated in three- dimensional motion analysis. Subjects completed 3 trials of sit-to-stand task in two conditions; “without visual feedback” and “with visual feedback”. Outcome measures were the interlimb symmetry of vertical ground reaction force, and joint kinematics and kinetics. Pain and strength of lower limbs were assessed. Findings Compared to “without visual feedback” condition, subjects moved with greater symmetry of vertical ground reaction force and joint kinetics when visual feedback was received. However, subjects continued to demonstrate interlimb difference for joint kinetics and vertical ground reaction force in the visual feedback condition. The increase in symmetry was not strongly influenced by physical impairments and subjects before and after total hip arthroplasty responded similarly to the feedback. Interpretations We concluded that in a single session, the visual feedback of weight bearing distribution had a positive immediate effect on movement symmetry during the sit-to-stand task. Future studies that assess long-term retention and functional benefits are warranted before visual feedback is incorporated in rehabilitation for this patient population.
... Patients with osteoarthritis in one limb are at risk of disease progression in the other limb, as it will be exposed to compensatory high peak forces and asymmetrical walking patterns (49)(50)(51). Indeed patients are likely to develop OA in the 'good' leg than in the ipsilateral knee OA following hip arthroplasty (50,52,53). Weight loss has been shown to reduce OA symptoms, presumably from reducing the peak forces experienced through these affected joints (54). ...
Thesis
Hip arthroplasty is a successful intervention for symptomatic end stage arthritis of the hip. However it remains an imperfect procedure due in many respects to the difficulty in reproducing biomechanics for each individual patient. Reproduction of femoral offset and leg length ensures appropriate muscle balancing which allows for hip biomechanics to be restored. In addition adequate soft tissue balancing reduces the risk of complications such as dislocations and nerve injuries. Post- operative functional performance may also be affected by the implant technology being used as well as surgical accuracy. However little is known as to what functional performance is to be expected following hip arthroplasty, especially when function is measured at fast speeds and walking inclines. This thesis will explore the gait of patients prospectively through pre to post-operative stages, in an attempt to ascertain what gait changes can be expected following hip arthroplasty. Furthermore the gait assessments will focus on higher end function, when walking at fast speeds. Following this, this thesis aims to assess whether gait differences are evident when different implants are used, and judge whether they may be a functional advantage to using different implants in hip reconstruction. Surgical accuracy is paramount, when avoiding complications alluded to earlier. This thesis explores whether rapid prototyping technology can be utilised to aid accurate insertion a femoral stem as part of a pre-clinical test. Finally this thesis will also test the association of implant size and failures that has been alluded to from national joint registries.
... Prior to THA, subjects preferentially shifted their weight toward the non-operated side and unloaded the operated side, as evidenced by the 24% lower peak VGRF on the operated limb. Previous authors have found similar weight bearing asymmetries in patients with hip OA using instrumented shoes [27] and conventional motion analysis [16,28]. The reduction in VGRF likely contributed to the reduced joint moments on the operated limb. ...
Article
The purpose of this study was to evaluate changes in movement patterns during a sit-to-stand (STS) task before and after total hip arthroplasty (THA), and to compare biomechanical outcomes after THA to a control group. Forty-five subjects who underwent THA and twenty-three healthy control subjects participated in three-dimensional motion analysis. Pre-operatively, subjects exhibited inter-limb movement asymmetries with lower vertical ground reaction force (VGRF) and smaller moments on the operated limb. Although there were significant improvements in movement symmetry 3months after THA, patients continued to demonstrate lower VGRF and smaller moments on the operated limb compared to non-operated and to control limbs. Future studies should identify the contributions of physical impairments and the influence of surgical approach on STS biomechanics. Copyright © 2015. Published by Elsevier Inc.
... Asymmetrical movement patterns are common in patients with unilateral weakness or pain. Individuals with unilateral lower limb musculoskeletal pathologies such as osteoarthritis, or after procedures such as total joint arthroplasty or anterior cruciate ligament reconstruction, preferentially unload the affected side and shift the weight to the non-affected side during sit-to-stand and squat tasks [1][2][3][4][5][6][7][8][9]. These asymmetries are particularly concerning in patients before and after total joint arthroplasty because weight bearing asymmetry is related to worse functional performance [9]. ...
Article
Weight bearing asymmetry is common in patients with unilateral lower limb musculoskeletal pathologies. The Nintendo Wii Balance Board (WBB) has been suggested as a low-cost and widely-available tool to measure weight bearing asymmetry in a clinical environment; however no study has evaluated the validity of this tool during dynamic tasks. Therefore, the purpose of this study was to determine the concurrent validity of force measurements acquired from the WBB as compared to laboratory force plates. Thirty-five individuals before, or within 1 year of total joint arthroplasty performed a sit-to-stand and return-to-sit task in two conditions. First, subjects performed the task with both feet placed on a single WBB. Second, the task was repeated with each foot placed on an individual laboratory force plate. Peak vertical ground reaction force (VGRF) under each foot and the inter-limb symmetry ratio were calculated. Validity was examined using Intraclass Correlation Coefficients (ICC), regression analysis, 95% limits of agreement and Bland-Altman plots. Force plates and the WBB exhibited excellent agreement for all outcome measurements (ICC=0.83-0.99). Bland-Altman plots showed no obvious relationship between the difference and the mean for the peak VGRF, but there was a consistent trend in which VGRF on the unaffected side was lower and VGRF on the affected side was higher when using the WBB. However, these consistent biases can be adjusted for by utilizing regression equations that estimate the force plate values based on the WBB force. The WBB may serve as a valid, suitable, and low-cost alternative to expensive, laboratory force plates for measuring weight bearing asymmetry in clinical settings. Copyright © 2015 Elsevier B.V. All rights reserved.
... Hip osteoarthritis (OA) is a common degenerative condition characterised by joint pain, inter-limb asymmetry and substantial loss of muscular strength and mass (Martinez-Ramirez et al., 2013;Rasch et al., 2007). Total hip arthroplasty (THA) is known to be an efficient way to relieve pain, provide better stability and functional capacity, and improve health-related quality of life (QOL) (Jinks et al., 2003;Jones et al., 2000;Wylde et al., 2009). ...
... The current study confirmed significant WBA in hip OA patients with mild-tomoderate pain, but only at peak GRF. This corresponds to results from Martinez-Ramirez et al. [10], who found asymmetries occur during the rise, but not in quiet standing after completion of the rise, in patients with late-stage hip OA. Although pain is a primary symptom in lower limb OA, pain and functional limitations do not always change concordantly [21]. ...
Article
Background: The objective of the present study was to investigate loading of the operated leg during quiet standing and sit-to-stand (STS) movement for 1 year after total hip arthroplasty (THA). Methods: One hundred and fifty-eight patients with end-stage hip osteoarthritis (OA) who had undergone unilateral primary THA participated in this study. The load distribution on the operated and non-operated legs was computed by measuring the vertical reaction force of the operated and non-operated legs during quiet standing and STS movement. We investigated the load distribution using Pressure Distribution Measurement Platform preoperatively and 1, 2, 3, 6, and 12 months postoperatively. Findings: Loading of the operated leg during quiet standing was restored 1 month postoperatively. Loading of the operated leg during STS movement was higher within 2 months postoperatively than the preoperative levels and continued to increase 1 year postoperatively. Loading of the operated leg was lower during STS movement than that during quiet standing, even 1 year postoperatively. Interpretation: A longitudinal and dynamic assessment of loading of the operated leg after THA is clinically important, and the loading during STS movement might continue to increase for a year after THA.
Article
Background: Painful unilateral cox arthrosis results in excessive forces passing through the "good leg." The impact of hip arthroplasty on contralateral leg gait has not been fully explored. We measured patients gait before and after arthroplasty, to answer 3 questions: (1) Are peak forces for the good legs outside the normal range? (2) Does arthroplasty protect contralateral limbs by reducing peak forces? and (3) Does arthroplasty result in a more symmetric and normal gait at fast walking speeds? Methods: This prospective, controlled study, assessed ground reaction forces before and 13 months (range, 6-21 months) after hip arthroplasty. Results: Peak ground reaction force in contralateral hips fell (1.45-1.38 times body weight, P = .04), whereas symmetry index maximum weight acceptance improved postoperatively (12.2 ± 11 vs 1.3 ± 6, P < .001). Conclusion: Although gait becomes more symmetrical, patients still experience higher peak loads than matched controls. These high forces may offer an explanation to the progression of arthrosis in lower limbs.
Article
Maximal and rapid strength characteristics of the knee extensor and flexor muscles play an important role in fall prevention and walking-related performances; however, few studies have investigated the ability of these variables to identify chair-rise performances in very old adults. To examine the effectiveness of maximal and rapid isometric strength characteristics of the knee extensors and flexors to differentiate between very old adults who are able (higher functioning) versus unable (lower functioning) to independently rise from a chair. Nine higher functioning (age, 87 ± 6 years) and 6 lower functioning (age, 89 ± 6 years) very old adults performed 2 isometric maximal voluntary contractions of the knee extensors and flexors. Peak moment and absolute and relative rate of moment development (RMD) at the early (0-50 ms) and late (0-200 ms) phases of muscle contraction were examined during each maximal voluntary contraction. Absolute and relative RMD values at 0 to 50 ms were greater (P = .02 and .03, respectively) in the higher functioning than in the lower functioning individuals for both the knee extensors and flexors. However, no group-related differences (P = .39-.58) were observed in either muscle group for peak moment or absolute and relative RMD at 0 to 200 ms. Early rapid moment production of the knee extensors and flexors may be an effective measure for discriminating between very old adults of different chair-rise performance abilities. Physical therapists and other practitioners may use these findings to help with the identification and early detection of older adults who are at a high risk for functional decline.
Article
Low limb rehabilitation training is recognized as a very effective technique to facilitate body recovery. To make rehabilitation more efficient, we need to monitor the whole progress and detect how well the patient improves. The physician could make an optimal treatment plan according to the patient's improvement only when the patient's condition is correctly evaluated. Also, it is essential to provide a rehabilitation assessment system which would enable more accurate tracking of patient's status and minimize the requirement of time-consuming manual evaluations conducted by skilled person. Traditionally, clinical rehabilitation assessment is performed manually, which is not only coarse but also time-consuming. In this paper, we propose an objective, quantitative and manual-independent assessment system for lower extremity rehabilitation. Four predictive variables, i.e. rang of motion (ROM), movement smoothness, trajectory error, and improved L-Z complexity of electromyographic signal (EMG), are explored besides conventional clinical assessment scales. A cost-effective and wearable human-independent device which mainly consists of two sensors (MPU6050 and HMC5883L), is developed to measure the ROM, movement smoothness and trajectory error. What's more, a 3D leg model is employed to visualize the leg motion in real-time on PC screen to increase the entertainment. Those physical quantities are more sensitive at the early stage of rehabilitation. And when the basic body function is recovered, the subtle rehabilitation improvement can only be detected by the intrinsic EMG signal. Therefore an improved L-Z complexity of EMG is applied to combine with physical assessment metrics. Compared with traditional L-Z complexity, the improved one proposed in this paper could reflect more precisely the underlying property of EMG signal. The future work is to integrate all the evaluation metrics, thus we introduce a BP network to quantize a final assessment outcome.
Article
Single-legged hop tests and isokinetic muscle torque are common outcome measures in the evaluation of knee function. The reliability of the single-legged hop tests in children has not been documented. The aim was to examine inter- and intrarater reliability of four single-legged hop tests and isokinetic muscle torque measurements in children. Twenty-eight sports-active children (12.4 ± 0.3 years old) were tested three times in two test sessions separated by 1 week. They performed four single-legged hop tests and concentric isokinetic torque measurements during knee extension and flexion. Inter- and intrarater reliability were calculated using the intraclass correlation coefficient (ICC 2,1). Relative terms of the standard error of measurement (SEM %) and smallest real difference (SRD %) were emphasized to allow comparison between the different variables. Twenty-six children were included for statistical analysis. ICCs for inter- and intrarater reliability were moderate to high for the hop tests (0.62-0.91) and isokinetic measurements (0.76-0.87). SEMs % were low for the hop tests (3.9-7.4 %) and the isokinetic measurements (5.2-8.9 %). SRDs % were 20.5 % or less for the hop tests, 15.7 % or less for knee extension, and 24.6 % or less for knee flexion. The single-legged hop tests and isokinetic muscle torque measurements demonstrated moderate-to-high reliability with low measurement error in sports-active children. A change above 20.5 % for the single-legged hop tests, 15.7 % for knee extension, and 24.6 % for knee flexion is necessary to represent a real change in knee function. LEVEL OF EVIDENCE: III.
Article
Full-text available
In the present study 10 healthy subjects were measured, performing sit-to-stand transfers in a natural way. Starting position and speed of movement were standardized. Sagittal kinematics, the ground reaction force, and muscle activity of nine leg muscles were recorded. During sit-to-stand transfer the mass centre of the body was moved forward and upward. Based on the velocity of the mass centre of the body three phases were distinguished. In horizontal direction forward rotation of the upper body contributed to the velocity of the mass centre of the body, whereas extension of the legs contributed considerably in vertical direction. After seat-off most muscles were concentrically active, whereas the shortening velocity of the rectus femoris was very low. Thus hip and knee joints were extended and a relatively high knee moment was delivered to control the ground reaction force in a slightly backward direction. Co-contraction of hamstrings and rectus femoris in sit-to-stand transfer was judged to be efficient.
Article
Full-text available
Osteoarthritis (OA) of the knee is associated with alterations in gait. As an alternative to force plates, instrumented force shoes (IFSs) can be used to measure ground reaction forces. This study evaluated the influence of IFS on gait pattern in patients with knee OA. Twenty patients with knee OA walked in a gait laboratory on IFS and control shoes (CSs). An optoelectronic system and force plate were used to perform 3D gait analyses. A comparison of temporal-spatial gait parameters, kinematics, and kinetics was made between IFS and CS. Patients wearing IFS showed a decrease in walking velocity and cadence (8%), unchanged stride length, an increase in stance time (13%), stride time (11%) and step width (14%). No differences were found in knee adduction moment or knee kinematics. Small differences were found in foot and ankle kinematics (2-5°), knee transverse moments (5%), ankle frontal (3%) and sagittal moments (1%) and ground reaction force (1-6%). The gait of patients with knee OA was only mildly influenced by the IFS, due to increased shoe height and weight and a change in sole stiffness. The changes were small compared to normal variation and clinically relevant differences. Importantly, in OA patients no effect was found on the knee adduction moment.
Article
Full-text available
Osteoarthritis (OA) can be used as a common name for a group of overlapping pathological conditions when the balance between the processes of degradation and synthesis, in individual parts of the cartilage, is disturbed and leads to gradual cartilage destruction. A preventive approach toward OA helps with a timely diagnosis and subsequent treatment of this disease. One of the significant risk factors affecting development of hip joint OA is the mechanism and magnitude of mechanical loading on the joint. The main motivation for this work was to verify the hypothesis involving a pathologic cycle (overloading - change of locomotion - overloading) as contributory to the development of OA and whether it can be stopped, or at least partly decelerated, by a suitable change of movement stereotypes. Providing that there is a natural balance of muscular action, from the beginning of OA, the development of OA can be significantly decelerated. The return to a natural force balance can be achieved using suitable exercise and strengthening of muscular structures. In order to verify the hypothesis, we undertook experimental measurements of gait kinematics and a computational analysis of the hip joint using the Finite Element Method.
Article
Full-text available
After total hip arthroplasty (THA), patients today (who tend to be younger and more active than those who previously underwent this surgical procedure) have high expectations regarding functional outcome. Therefore, patients need to be well informed about recovery of physical functioning after THA. The purpose of this study was to review publications on recovery of physical functioning after THA and examine the degree of recovery with regard to 3 aspects of functioning (ie, perceived physical functioning, functional capacity to perform activities, and actual daily activity in the home situation). Data were obtained from the MEDLINE and EMBASE databases from inception to July 2009, and references in identified articles were tracked. Prospective studies with a before-after design were included. Patients included in the analysis had to have primary THA for osteoarthritis. Two reviewers independently checked the inclusion criteria, conducted the risk of bias assessment, and extracted the results. Data were pooled in a meta-analysis using a random-effects model. A total of 31 studies were included. For perceived physical functioning, patients recovered from less than 50% preoperatively to about 80% of that of controls (individuals who were healthy) 6 to 8 months postsurgery. On functional capacity, patients recovered from 70% preoperatively to about 80% of that of controls 6 to 8 months postsurgery. For actual daily activity, patients recovered from 80% preoperatively to 84% of that of controls at 6 months postsurgery. Only a few studies were retrieved that investigated the recovery of physical functioning longer than 8 months after surgery. Compared with the preoperative situation, the 3 aspects of physical functioning showed varying degrees of recovery after surgery. At 6 to 8 months postoperatively, physical functioning had generally recovered to about 80% of that of controls.
Article
Full-text available
Degenerative musculoskeletal disorders are among the most frequent diseases occurring in adulthood, often impairing patients' functional mobility and physical activity. The aim of the present study was to investigate and compare the impact of three frequent degenerative musculoskeletal disorders--knee osteoarthritis (knee OA), hip osteoarthritis (hip OA) and lumbar spinal stenosis (LSS)--on patients' walking ability. The study included 120 participants, with 30 in each patient group and 30 healthy control individuals. A uniaxial accelerometer, the StepWatch™ Activity Monitor (Orthocare Innovations, Seattle, Washington, USA), was used to determine the volume (number of gait cycles per day) and intensity (gait cycles per minute) of walking ability. Non-parametric testing was used for all statistical analyses. Both the volume and the intensity of walking ability were significantly lower among the patients in comparison with the healthy control individuals (p < 0.001). Patients with LSS spent 0.4 (IQR 2.8) min/day doing moderately intense walking (>50 gait cycles/min), which was significantly lower in comparison with patients with knee and hip OA at 2.5 (IQR 4.4) and 3.4 (IQR 16.1) min/day, respectively (p < 0.001). No correlations between demographic or anthropometric data and walking ability were found. No technical problems or measuring errors occurred with any of the measurements. Patients with degenerative musculoskeletal disorders suffer limitations in their walking ability. Objective assessment of walking ability appeared to be an easy and feasible tool for measuring such limitations as it provides baseline data and objective information that are more precise than the patients' own subjective estimates. In everyday practice, objective activity assessment can provide feedback for clinicians regarding patients' performance during everyday life and the extent to which this confirms the results of clinical investigations. The method can also be used as a way of encouraging patients to develop a more active lifestyle.
Article
Full-text available
Standard total hip arthroplasty (THA) is the established surgical treatment for patients older than 65 years with progressive osteoarthritis but survivorship curves wane in patients younger than 50. Resurfacing hip arthroplasty (RHA) is an alternative for younger, active patients reportedly providing superior range of motion. Quantitative investigation of functional recovery following arthroplasty may elucidate limitations that aid in device selection. Although limited long-term kinematic data are available, the early rate of recovery and gait compensations are not well described. This information may aid in refining rehabilitation protocols based on limitations specific to the implant. We presumed hip motion and forces for subjects receiving RHA are more similar to age-matched controls during physically demanding tasks, such as stair negotiation, at early time points than those for THA. In a pilot study, we quantified walking and stair negotiation preoperatively and 3 months postoperatively for seven patients with RHA (mean age, 49 years), seven patients with standard THA (mean age, 52 years), and seven age-matched control subjects (mean age, 56 years). Although both treatment groups demonstrated trends toward functional recovery, the RHA group had greater improvements in hip extension and abduction moment indicating typical loading of the hip. Further investigation is needed to determine if differences persist long term or are clinically meaningful.
Article
Full-text available
Outcome evaluations are of primary concern in contemporary medical practice. Questionnaires are being used increasingly to provide input data for such outcomes evaluation. This study comprised 50 primary total hip arthroplasties in 36 patients who had undergone the procedure at least 12 months before enrollment. Each patient completed a self-report Harris Hip Score (HHS) 30 days before a formal evaluation by an independent orthopaedic surgeon that included a HHS. Comparison was made between the completed responses to the individual items on the self-report HHS and surgeon-assessed HHS. Concordance of item response and kappa statistic were calculated. Overall the self-report and surgeon-assessed HHS showed excellent concordance. The results of this study support the use of the HHS as a self-report instrument.
Article
Full-text available
Concurrent head-to-head comparisons of healthcare interventions regarding cost-utility are rare. The concept of favorable cost-effectiveness of total hip or knee arthroplasty is thus inadequately verified. In a trial involving several thousand patients from 10 medical specialties, 223 patients who were enrolled for hip or knee replacement surgery were asked to fill in the 15D health-related quality of life (HRQoL) survey before and after operation. Mean (SD) HRQoL score (on a 0-1 scale) increased in primary hip replacement patients (n = 96) from 0.81 (0.084) preoperatively to 0.86 (0.12) at 12 months (p < 0.001). In revision hip replacement (n = 24) the corresponding scores were 0.81 (0.086) and 0.82 (0.097) respectively (p = 0.4), and in knee replacement (n = 103) the scores were 0.81 (0.093) and 0.84 (0.11) respectively (p < 0.001). Of 15 health dimensions, there were statistically significant improvements in moving, usual activities, discomfort and symptoms, distress, and vitality in both primary replacement groups. Mean cost per quality-adjusted life year (QALY) gained during a 1-year period was euro 6,710 for primary hip replacement, euro 52,274 for revision hip replacement, and euro 13,995 for primary knee replacement. Hip and knee replacement both improve HRQoL. The cost per QALY gained from knee replacement is twice that gained from hip replacement.
Article
Full-text available
Ground reaction force (GRF) measurement is important in the analysis of human body movements. The main drawback of the existing measurement systems is the restriction to a laboratory environment. This paper proposes an ambulatory system for assessing the dynamics of ankle and foot, which integrates the measurement of the GRF with the measurement of human body movement. The GRF and the center of pressure (CoP) are measured using two six-degrees-of-freedom force sensors mounted beneath the shoe. The movement of foot and lower leg is measured using three miniature inertial sensors, two rigidly attached to the shoe and one on the lower leg. The proposed system is validated using a force plate and an optical position measurement system as a reference. The results show good correspondence between both measurement systems, except for the ankle power estimation. The root mean square (RMS) difference of the magnitude of the GRF over 10 evaluated trials was (0.012 +/- 0.001) N/N (mean +/- standard deviation), being (1.1 +/- 0.1)% of the maximal GRF magnitude. It should be noted that the forces, moments, and powers are normalized with respect to body weight. The CoP estimation using both methods shows good correspondence, as indicated by the RMS difference of (5.1 +/- 0.7) mm, corresponding to (1.7 +/- 0.3)% of the length of the shoe. The RMS difference between the magnitudes of the heel position estimates was calculated as (18 +/- 6) mm, being (1.4 +/- 0.5)% of the maximal magnitude. The ankle moment RMS difference was (0.004 +/- 0.001) Nm/N, being (2.3 +/- 0.5)% of the maximal magnitude. Finally, the RMS difference of the estimated power at the ankle was (0.02 +/- 0.005) W/N, being (14 +/- 5)% of the maximal power. This power difference is caused by an inaccurate estimation of the angular velocities using the optical reference measurement system, which is due to considering the foot as a single segment. The ambulatory system considers separate heel and forefoot segments, thus allowing an additional foot moment and power to be estimated. Based on the results of this research, it is concluded that the combination of the instrumented shoe and inertial sensing is a promising tool for the assessment of the dynamics of foot and ankle in an ambulatory setting.
Article
Full-text available
Changes in performance of standing up from a chair have been related to measures of strength or power. However, the sit-to-stand (STS) transfer requires that the individual exerts forces with appropriate magnitude and timing. These coordinative aspects have received less attention. This study aims to analyze differences in STS performance in older people based on measures that are derived from ground reaction forces (GRFs) during STS transfer. One hundred thirty-five participants (84.5% women; mean age 82.5 years) stood up from a chair as fast as possible. Time of stabilization after reaching an upright position, power, maximum vertical GRF, increase of vertical GRF, overshoot of vertical GRF over body weight, and left-right difference of GRF were measured by a force plate under each foot. To explain variance of total time to stand up, these variables were used as independent variables in a linear regression model. Eighty-one percent of variance of total time to stand up was explained by the independent variables. The strongest predictor of total time was time of stabilization (F = 459.4). Another model of linear regression explained 37% of variance of time to reach an upright position, with increase of GRF as the strongest predictor (F = 38.3). Influence of maximum vertical GRF was weak in both models. Variables related to coordination of strength, measured during STS transfer, were able to explain a high proportion of variance of time to rise from a chair. Stabilization after reaching an upright position seems to be a parameter worth further investigation.
Article
Full-text available
Asymmetric limb loading persists well after unilateral total hip replacement surgery and represents a risk of the development of osteoarthritis in the non-operated leg. Here we studied bilateral limb loading in hip arthroplasty patients for a variety of everyday activities. Twenty-seven patients and 27 healthy age-matched control subjects participated in the study. They were asked to stand up from a chair, to stand quietly, to perform isometric maximal voluntary contractions and to walk along a 10 m path at a natural and fast speed. Two force platforms measured vertical forces under each foot during quiet standing and sit-to-stand maneuver. Temporal variables of gait were measured using footswitches. In all tasks patients tended to preferentially load the non-operated limb, though the amount of asymmetry depended on the task being most prominent during standing up (inter-limb weight bearing difference exceeded 20%, independent of speed or visual conditions). In contrast, when performing maximal voluntary contractions, or during walking and quiet standing, the inter-limb difference in the maximal force production, stance/swing phase durations or weight bearing was typically less than 10%. The results suggest that the amount of asymmetry might not be necessarily the same for different tasks. Asymmetric leg loading in patients can be critical during sit-to-stand maneuver in comparison with quiet standing and walking, and visual information seems to play only a minor role in the control of the weight-bearing ability. The proposed asymmetry indices might be clinically significant for development of post-surgical rehabilitation.
Article
The sit-to-stand (STS) maneuver is a common aspect of mobility. In the following review, the mechanics of the maneuver are briefly reviewed. Thereafter, alternatives for measuring STS performance are described. The Five-Repetition STS Test (FRSTST) is discussed in detail. This discussion emphasizes the measurement properties of the test. For clinicians working with older adults, there is considerable support for using the FRSTST as a measurement of mobility.
Article
Primary disabling conditions, such as amputation, not only limit mobility, but also predispose individuals to secondary musculoskeletal impairments, such as osteoarthritis (OA) of the intact limb joints, that can result in additive disability. Altered gait biomechanics that cause increased loading of the intact limb have been suggested as a cause of the increased prevalence of intact limb knee and hip osteoarthritis in this population. Optimizing socket fit and prosthetic alignment, as well as developing and prescribing prosthetic feet with improved push-off characteristics, can lead to reduced asymmetric loading of the intact limb and therefore are potential strategies to prevent and treat osteoarthritis in the amputee population. Research on disabled populations associated with altered biomechanics offers an opportunity to focus on the mechanical risk factors associated with this condition. Continued research into the causes of secondary disability and the development of preventive strategies are critical to enable optimal rehabilitation practices to maximize function and quality of life in patients with disabilities.
Article
Controlled laboratory study using a cross-sectional design. To compare lower extremity force applications during a sit-to-stand (STS) task with and without upper extremity assistance in older individuals post-hip fracture to those of age-matched controls. A recent study documented the dependence on upper extremity assistance and the uninvolved lower limb during an STS task in individuals post-hip fracture. This study extends this work by examining the effect of upper extremity assistance on symmetry of lower extremity force applications. Twenty-eight community-dwelling elderly subjects, 14 who had recovered from a hip fracture and 14 controls, participated in the study. All participants were independent ambulators. Four force plates were used to determine lower extremity force applications during an STS task with and without upper extremity assistance. The summed vertical ground reaction forces (vGRFs) of both limbs were used to determine STS phases (preparation/rising). The lower extremity force applications were assessed statistically using analysis of variance models. During the preparation phase, side-to-side symmetry of the rate of force development was significantly lower for the hip fracture group for both STS tasks (P<.001). During the rising phase, the vGRF impulse of the involved limb was significantly lower for the hip fracture group for both STS tasks (P = .045). The vGRF impulse for the uninvolved limb was significantly increased when participants with hip fracture did not use upper extremity assistance compared to elderly controls (P = .002). This resulted in a significantly lower vGRF symmetry for the hip fracture group during both STS tasks (P<.001). Participants with hip fracture who were discharged from rehabilitative care demonstrated decreased side-to-side symmetry of lower extremity loading during an STS task, irrespective of whether upper extremity assistance was provided. These findings suggest that learned motor control strategies may influence movement patterns post-hip fracture.
Article
The external knee adduction moment (KAdM) during gait is an important parameter in patients with knee osteoarthritis (OA). KAdM measurement is currently restricted to instruments only available in gait laboratories. However, ambulatory movement analysis technology, including instrumented force shoes (IFS) and inertial and magnetic measurement systems (IMMS), can measure kinetics and kinematics of human gait free of laboratory restrictions. The objective of this study was a quantitative validation of the accuracy of the KAdM in patients with knee OA, when estimated with an ambulatory-based method (AmbBM) versus a laboratory-based method (LabBM). AmbBM is employing the IFS and a linked-segment model, while LabBM is based on a force plate and optoelectronic marker system. Effects of ground reaction force (GRF), centre of pressure (CoP), and knee joint position measurement are evaluated separately. Twenty patients with knee OA were measured. The GRFs showed differences up to 0.22 N/kg, the CoPs showed differences up to 4 mm, and the medio-lateral and vertical knee position showed differences to 9 mm, between AmbBM and LabBM. The GRF caused an under-estimation in KAdM in early stance. However, this effect was counteracted by differences in CoP and joint position, resulting in a net 5% over-estimation. In midstance and late stance the accuracy of the KAdM was mainly limited by use of the linked-segment model for joint position estimation, resulting in an under-estimation (midstance 6% and late stance 22%). Further improvements are needed in the estimation of joint position from segment orientation.
Article
Regaining effective postural control after lower limb amputation requires complex adaptation strategies in both the prosthesis side and the non-amputated side. The objective in this study is to determine the individual contribution of the ankle torques generated by both legs in balance control during dynamic conditions. Subjects (6 transfemoral and 8 transtibial amputees) stood on a force platform mounted on a motion platform and were instructed to stand quietly. The experiment consisted of 1 static and 3 perturbation trials of 90 s duration each. The perturbation trials consisted of continuous randomized sinusoidal platform movements of different amplitude in the sagittal plane. Weight distribution during the static and dynamic perturbation trials was calculated by dividing the average vertical force below the prosthesis foot by the sum of forces below both feet. The Dynamic Balance Control represents the ratio between the stabilizing mechanism of the prosthetic leg and the stabilizing mechanism of the non-amputated leg. The stabilizing mechanism is calculated from the corrective ankle torque in response to sway. The relationship between the prosthetic ankle stiffness and the performance during the platform perturbations was calculated. All patients showed a (non-significant) weight bearing asymmetry in favor of the non-amputated leg. The Dynamic Balance Control ratio showed that the contribution of both legs to balance control was even more asymmetrical. Moreover, the actual balance contribution of each leg was not tightly coupled to weight bearing in each leg, as was the case in healthy controls. There was a significant positive correlation between the prosthetic ankle stiffness and the Dynamic Balance Control. The Dynamic Balance Control provides, in addition to weight distribution, information to what extent the stabilizing mechanism of the corrective ankle torque of both legs contributes to balance control. Knowledge of the stiffness properties may optimize the prescription process of prosthetic foot in lower leg amputee subjects in relation to standing stability.
Article
Little is known about the functional performance of patients after revision total hip arthroplasty with major acetabular bone impaction grafting. In general, these patients are assumed to perform worse due to a more advanced stage of periarticular tissue degeneration and multiple surgeries compared with patients with primary total hip arthroplasty (THA). The main purpose of this study was to quantify the differences in performance of the sit-to-stand (STS) movement between patients with primary THA and patients with revision THA. In this study, the STS movement was analyzed kinematically (knee and hip angular extension velocity) and kinetically (loading symmetry ratio). Ten patients after primary THA and 10 patients after revision THA with acetabular bone impaction grafting were compared using these 3 rising parameters. The patients with revision THA performed the STS movement comparably to the patients with primary THA; there were no differences in knee and hip velocity or leg asymmetry during rising. The study focused only on kinetic and kinematic aspects, and only patients who were satisfied with their THA were involved. This study showed that patients after a revision THA with acetabular bone impaction grafting and cement did not perform the STS movement differently, either kinematically or kinetically, compared with patients with a primary THA.
Article
A Sit to Stand task following a hip fracture may be achieved through compensations (e.g. bilateral arms and uninvolved lower extremity), not restoration of movement strategies of the involved lower extremity. The primary purpose was to compare upper and lower extremity movement strategies using the vertical ground reaction force during a Sit to Stand task in participants recovering from a hip fracture to control participants. The secondary purpose was to evaluate the correlation between vertical ground reaction force variables and validated functional measures. Twenty eight community dwelling older adults, 14 who had a hip fracture and 14 control participants completed the Sit to Stand task on an instrumented chair designed to measure vertical ground reaction force, performance based tests (Timed up and go, Berg Balance Scale and Gait Speed) and a self report Lower Extremity Measure. A MANOVA was used to compare functional scales and vertical ground reaction force variables between groups. Bivariate correlations were assessed using Pearson Product Moment correlations. The vertical ground reaction force variables showed significantly higher bilateral arm force, higher uninvolved side peak force and asymmetry between the involved and uninvolved sides for the participants recovering from a hip fracture (Wilks' Lambda=3.16, P=0.019). Significant correlations existed between the vertical ground reaction force variables and validated functional measures. Participants recovering from a hip fracture compensated using their arms and the uninvolved side to perform a Sit to Stand. Lower extremity movement strategies captured during a Sit to Stand task were correlated to scales used to assess function, balance and falls risk.
Article
Assessing the outcomes of patients following surgical interventions is a challenging task. Traditionally the end results of joint replacement were based on morbidity/mortality rates and operative complications. The modern approach to outcomes following Orthopaedic surgery has shifted from the success or failure of implants towards patient satisfaction and the quality of life achieved. The aim of this paper was to identify and analyse the common scoring systems present in the medical literature for evaluating outcomes after hip interventions. A pub-med search was performed using terms 'scoring system, functional outcomes, hip joint'. Specific limitations and exclusion criteria were used and the reference lists of the articles included in the study were subjected to further analysis for identification of additional relevant papers. 293 articles were identified of which 40 met the inclusion criteria. The outcome measures were divided into: (i) hip specific outcomes, (ii) disease-specific measures and (iii) generic quality of life measures. Based on our analysis, we would recommend a combination of the hip specific Oxford Hip Score (OHS) and the disease specific WOMAC score. The OHS is quick and easy to complete, has a very high response rate and is free from clinician bias. On the other hand, the majority of hip pathology is related to degenerative disease, thus making the WOMAC the most appropriate measure to use. Where comparison between different conditions is required, then an additional generic quality of life (QOL) score, such as EQ5D, that can enable comparisons in cost-effectiveness term can be used. The ideal outcome measure should be one that is specific for the hip joint, possesses a generic component and takes into consideration co-morbidities and the use of walking aids. Although many validated generic measures exist, additional validation studies, including the OHS, are desirable to evaluate all the hip specific measures of outcome.
Article
Total hip arthroplasty (THA) is a common surgical procedure for patients suffering from osteoarthritis to relieve their pain and to attempt to restore their normal locomotion patterns. Although this procedure does not restore normal mobility during activities of daily living, it remains unclear how it affects the joint mechanics of both lower limbs during stair negotiation tasks. Hence, we compared the 3D joint mechanics of both lower limbs of THA patients with matched healthy controls during stair ascent and stair descent. 3D kinematics and kinetics of both lower limbs were recorded for 20 patients having undergone unilateral THA and 20 healthy, age and body mass index matched control participants. The THA patients generated limited power at the operated hip joint, and thus compensated with larger power generation at the contralateral ankle to lift the body weight to the next step. This stair ambulation strategy, as well as others, adopted by the THA patients implied decreased activation of the lower limb musculature, which may be indicative of a muscle strength deficiency or a post-operatively adopted protective mechanism to unload the prosthesis. These asymmetric power production patterns should be addressed in rehabilitation programs pre- and post-operatively.
Article
Gait analysis in orthopaedic and neurological examinations is important; however, few studies assess gait variability at different walking speeds in patients with varying degrees of hip osteoarthritis. We aimed to clarify (1) how different controlled speeds and (2) various severities of hip osteoarthritis influence gait variability. Gait variability was described by the standard deviation (SD) of the spatial-temporal and mean standard deviation (MeanSD) of angular parameters. The spatial positions of the anatomical points for calculating gait parameters were determined in 20 healthy elderly controls and 20 patients with moderate and 20 patients with severe hip osteoarthritis with a zebris CMS-HS ultrasound-based motion analysis system at three walking speeds. The SD of the spatial-temporal and MeanSD of angular parameters of gait, which together describe gait variability, significantly depended on speed and osteoarthritis severity. The lowest variability in the gait was found near the self-selected walking speeds. Hip joint degeneration significantly worsened variability on the affected side, with non-affected joints and the pelvis compensating by increasing flexibility and adapting to step-by-step motions. Particular attention must be paid to improving gait stability and the reliability of limb movements in the presence of and increasing severity of osteoarthritis.
Article
This study proposes a method to assess foot placement during walking using an ambulatory measurement system consisting of orthopaedic sandals equipped with force/moment sensors and inertial sensors (accelerometers and gyroscopes). Two parameters, lateral foot placement (LFP) and stride length (SL), were estimated for each foot separately during walking with eyes open (EO), and with eyes closed (EC) to analyze if the ambulatory system was able to discriminate between different walking conditions. For validation, the ambulatory measurement system was compared to a reference optical position measurement system (Optotrak). LFP and SL were obtained by integration of inertial sensor signals. To reduce the drift caused by integration, LFP and SL were defined with respect to an average walking path using a predefined number of strides. By varying this number of strides, it was shown that LFP and SL could be best estimated using three consecutive strides. LFP and SL estimated from the instrumented shoe signals and with the reference system showed good correspondence as indicated by the RMS difference between both measurement systems being 6.5 ± 1.0 mm (mean ± standard deviation) for LFP, and 34.1 ± 2.7 mm for SL. Additionally, a statistical analysis revealed that the ambulatory system was able to discriminate between the EO and EC condition, like the reference system. It is concluded that the ambulatory measurement system was able to reliably estimate foot placement during walking.
Article
Ground reaction forces (GRFs) are often used in inverse dynamics analyses to determine joint loading. These GRFs are usually measured using force plates (FPs). As an alternative, instrumented force shoes (FSs) can be used, which have the advantage over FPs that they do not constrain foot placement. This study tested the FS system in one normal weight subject (77kg) performing 19 different lifting, pushing and pulling and walking tasks. Kinematics were measured with an optoelectronic system and the GRFs and the positions of the centre of pressure (CoP) were synchronously measured with FPs and FSs. Differences between the outcomes of the two measurement systems (i.e. CoP and GRFs) and the resulting ankle and L5/S1 joint moments were determined at the instant of the peak GRF (DaPF). For most lifting and pushing and pulling tasks, the difference between the FP and FS measurements remained small: GRF DaPF remained below 3% body weight, CoP DaPF remained below 10mm, ankle moment DaPF remained below 7% of the peak total ankle moment that occurred during normal walking and L5/S1 moment DaPF remained below 7% of the peak total L5/S1 moment that occurred during normal symmetric lifting. More substantial differences were only found in the maximal pushing tasks. For the walking tasks, peak vertical GRFs were somewhat underestimated. However, differences in ankle and L5/S1 moments remained small, i.e. DaPF below 7% of the peak total moment that occurred during normal walking.
Article
Although total hip arthroplasty (THA) is known to be a successful surgical procedure to alleviate hip pain and to improve health-related quality of life, these outcome measures in THA patients do not reach those of the general population. As a result, several investigators have assessed THA patients' gait mechanics, but most of them have ignored adjacent joints, as well as the effect that THA may have on the non-operated limb. The purpose of this investigation was to determine the effect of THA on the pelvis, hip, knee and ankle joint kinematics, as well as the hip, knee and ankle kinetics of both the operated and non-operated limbs during walking. These data were recorded for 20 patients having undergone unilateral THA and 20 healthy, matched control participants. Results revealed that the gait mechanics of THA patients did not return to normal 10.6 months, on average (+/-2.6 mo), following surgery. THA patients walked with lower operated-hip abduction moments, sagittal-plane range of motion, as well as lower generated and absorbed power, that may be consequential to pain-avoidance strategies adopted pre-operatively or to apprehensions associated with their new prosthesis. They also displayed various kinematic adaptations at the ankle joint of the operated limb and at the non-operated hip joint that may be leaving them at risk of developing other joint diseases. Further investigation is needed to confirm the reasons why THA patients' gait mechanics do not return to normal following surgery to develop better surgical techniques and/or rehabilitation programs.
Article
L5/S1, hip and knee moments during manual lifting tasks are, in a laboratory environment, frequently established by bottom-up inverse dynamics, using force plates to measure ground reaction forces (GRFs) and an optoelectronic system to measure segment positions and orientations. For field measurements, alternative measurement systems are being developed. One alternative is the use of small body-mounted inertial/magnetic sensors (IMSs) and instrumented force shoes to measure segment orientation and GRFs, respectively. However, because IMSs measure segment orientations only, the positions of segments relative to each other and relative to the GRFs have to be determined by linking them, assuming fixed segment lengths and zero joint translation. This will affect the estimated joint positions and joint moments. This study investigated the effect of using segment orientations only (orientation-based method) instead of using orientations and positions (reference method) on three-dimensional joint moments. To compare analysis methods (and not measurement methods), GRFs were measured with a force plate and segment positions and/or orientations were measured using optoelectronic marker clusters for both analysis methods. Eleven male subjects lifted a box from floor level using three lifting techniques: a stoop, a semi-squat and a squat technique. The difference between the two analysis methods remained small for the knee moments: <4%. For the hip and L5/S1 moments, the differences were more substantial: up to 8% for the stoop and semi-squat techniques and up to 14% for the squat technique. In conclusion, joint moments during lifting can be estimated with good accuracy at the knee joint and with reasonable accuracy at the hip and L5/S1 joints using segment orientation and GRF data only.
Article
Functional recovery of patients after a total knee arthroplasty (TKA) usually is measured with questionnaires. However, these self-report measures assess the patient's perspective on his or her ability to perform a task. Performance-based tests are needed to assess the patient's actual ability to perform a task. The main purpose of this study was to quantify improvement in performance of the sit-to-stand movement of patients with a TKA. Design and In this prospective study of 16 patients with end-stage knee osteoarthritis followed by a TKA, the maximal knee angular extension velocity and amount of unloading (shifting weight) of the affected leg during the sit-to-stand movement and the visual analog scale score for pain were assessed preoperatively and 6 months and 1 year postoperatively. These data were compared with data for a control group of individuals who were healthy (n=27). Before surgery, the participants in the TKA group unloaded their affected leg, but within 6 months after implantation, the affected leg was almost fully loaded again and comparable to the loading symmetry ratio of the control group. Furthermore, knee extension velocity also had increased, but remained lower than that of the control group. The changes in knee extension velocity took place during the first 6 months, after which a plateau was visible. Limitations A potential limitation of the study design was that the patients were not perfectly matched with the control subjects. Implantation of a total knee prosthesis partly improved performance of the sit-to-stand movement. Participants in the TKA group could fully load their operated leg, but they could not generate enough knee angular velocity during rising compared with the control group.
Article
Quantification of the biomechanical factors that underlie the inability to rise from a chair can help explain why this disability occurs and can aid in the design of chairs and of therapeutic intervention programs. Experimental data collected earlier from 17 young adult and two groups of elderly subjects, 23 healthy and 11 impaired, rising from a standard chair under controlled conditions were analyzed using a planar biomechanical model. The joint torque strength requirements and the location of the floor reaction force at liftoff from the seat in the different groups and under several conditions were calculated. Analyses were also made of how body configurations and the use of hand force affect these joint torques and reaction locations. In all three groups, the required torques at liftoff were modest compared to literature data on voluntary strengths. Among the three groups rising with the use of hands, at the time of liftoff from the seat, the impaired old subjects, on an average, placed the reaction force the most anterior, the healthy old subjects placed it intermediately and the young subjects placed it the least anterior, within the foot support area. Moreover, the results suggest that, at liftoff, all subjects placed more importance on locating the floor reaction force to achieve acceptable postural stability than on diminishing the magnitudes of the needed joint muscle strengths.
Article
A formal definition of human standing up and sitting down movements based on sagittal plane goniometric and force plate data from 20 normal subjects is presented. This definition is comparable to the established gait cycle diagram, and consists of defined characteristic events and relative time intervals between them. The characteristic events are selected primarily on changes in ground reaction forces. The terminology proposed may be valuable for introducing more formalized and standardized reporting of both qualitative and quantitative studies in both normals and in patients. This presentation is directed toward the process of defining generally acceptable standards for human standing up and sitting down movements.
Article
This study examined the validity of the assumption of bilateral lower extremity joint moment symmetry during the sit-to-stand motion for a group of young (n = 7) and a group of elderly (n = 7) female subjects. Two force plates and a motion analysis system were used to determine peak joint moments at the ankles, knees, and hips following liftoff from a chair. Statistically, bilateral asymmetries in peak joint moments were found at the knee joint in the young group [a right to left difference of 0.43% BW x BH (body weight x body height)] and at the hip joint in both subject groups (differences of 0.20% BW x BH and 1.09% BW x BH for the young and elderly subjects, respectively). Subsequent data analysis, using an algorithm that assumed bilateral ground reaction force (GRF) symmetry, was performed to determine whether the bilateral differences were a result of kinematic or GRF asymmetry. It was concluded from these results that both the kinematic and GRF data account for the bilateral asymmetry. The results of the subsequent analysis also showed that the method which assumed bilateral GRF symmetry underestimated the peak joint moments at the ankles, knees, and hips, with the greatest difference between methods being 0.10% BW x BH for the ankle joint. The results of this study suggest that the assumption of bilateral symmetry of lower extremity joint moments during the sit-to-stand is not valid. However, the biomechanical significance of the errors associated with assuming symmetry must also be taken into account.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
The purpose of this study was to compare patients' and physicians' evaluations of the results of 147 total hip arthroplasties. The patients and physicians independently evaluated pain and over-all satisfaction with the outcome of the procedure using a 10.0-centimeter visual-analog scale. They also answered a questionnaire with which they assessed general health, functional ability, and pain. The mean (and standard deviation) analog rating for pain (with 0.0 centimeters indicating no pain and 10.0 centimeters, severe pain) was 1.7 +/- 2.6 centimeters as assessed by the patients and 1.1 +/- 1.8 centimeters as assessed by the physicians (p < 0.001, paired t test). The mean analog rating for over-all satisfaction (with 0.0 centimeters indicating poor and 10.0 centimeters, excellent) was 8.6 +/- 2.1 centimeters as assessed by the patients and 8.8 +/- 1.7 centimeters as assessed by the physicians (p = 0.07, paired t test). There was a marked disparity between the patients' and the physicians' scores when the patients assigned a low score to a particular area. For the thirty patients who rated the pain as more than 4.0 centimeters, the mean analog rating was 6.8 +/- 2.1 centimeters according to the patients, while it was 3.6 +/- 2.7 centimeters according to the physicians (p < 0.001, linear regression). The mean analog rating for over-all satisfaction according to the nineteen patients who rated this parameter as less than 7.0 centimeters was 3.8 +/- 2.0 centimeters, while the mean rating according to the physicians 6.5 +/- 2.8 centimeters (p < 0.001, linear regression). The patients' and physicians' evaluations were similar regarding the results of the total hip arthroplasty when the patients had little or no pain and were satisfied with the result. However, the disparity increased as the patients' ratings for pain increased and their ratings for over-all satisfaction decreased. This study highlights a discrepancy between patients' and physicians' evaluations of the results of total hip arthroplasty. This discrepancy increased when the patient was not satisfied with the outcome. The use of patients' self-administered questionnaires as well as traditional physician-generated assessments may provide a more complete evaluation of the results of total hip arthroplasty.
Article
High reliability and validity of clinical rating schemes is crucial for their use as outcome measurements of treatment of hip and knee osteoarthritis. In this paper, we review the empirical evidence on the reliability and validity of commonly used clinical scores. Clinical scores and related reliability and validity studies were identified by systematic literature search. Scores were classified according to the type and joint. Reliability and validity studies were characterized according to design, population, number and qualification of observers, number of measurements, time interval between repeat measurements and results. Reliability and validity studies were reported for only 6 and 15 of the 45 identified clinical scores, respectively. Although comparisons are difficult due to differences in study design, relatively high reliability was reported for most measurements of pain, stiffness, and physical function, while results are less conclusive for clinical signs. Most validity studies focused on the correlation between various scores. Correlation was generally found to be high for overall numerical ratings, but scores often differed with respect to the interpretation of these ratings. Validity has been more comprehensively studied for Lequesne's scores, WOMAC, and ILAS, and these scores have shown satisfactory responsiveness to different treatment effects. Overall, knowledge on reliability and validity of clinical scores of hip and knee osteoarthritis is limited, underlining the need for further properly designed and conducted studies.
Article
An evaluation of patients’ quality of life before, 6 weeks and 6 months after total hip replacement surgery Annually, throughout the world, more than 800 000 primary total hip replacement surgery procedures are performed on patients suffering from hip joint arthrosis. Since 1991, ≈11 000 of these procedures are performed annually in Sweden. This study aimed to investigate any changes in the patients’ life quality 6 weeks and 6 months after their total hip replacement surgery had been performed, compared to that immediately prior to the operation. It also aimed to examine the reason for surgery, the types of prostheses used, postoperative pain, complications and the actual usage of ambulation support. The Sickness Impact Profile self-appraisal instrument, together with personal patient interviews have been used as the basis of the research. A total of 51 patients responded to the quality of life instrument prior to their operation, 47 of these participated 6 weeks after the operation, and 40 patients 6 months after the operation. Significant differences in patients’ total, physical and psychosocial quality of life 6 months postoperatively compared to the situation prior to the operation were found, but not between the situation before and 6 weeks after the total hip replacement surgery. The majority of patients were of the opinion that it was more important that the pain had disappeared or decreased, than any overall increase in the quality of life. Postoperative complications occurred within 6 weeks, and even after 6 months some patients still suffered from these.
Article
Although the Harris hip score frequently is used to assess the outcome of total hip replacement, only a few minor validity tests have been presented. The aim of this study was to perform a validity test of the Harris hip score and to test its reliability. Two cohorts were studied. First, 58 patients who had undergone total hip replacement 2 to 10 years earlier were evaluated by an orthopaedic surgeon and an experienced physiotherapist using the Harris hip score. The patients also answered the Western Ontario and McMaster University Osteoarthritis Index and the Medical Outcomes Study 36-Item Short-Form Health Survey. Second, 1,056 patients answered the Western Ontario and McMaster University Osteoarthritis Index and the Medical Outcomes Study 36-Item Short-Form Health Survey questionnaires. The results were compared with those of a subcohort of 344 patients who were evaluated using the Harris hip score. The following items were tested: content validity, convergent and divergent construct validity, criterion validity, test and retest reliability, internal consistency reliability, and interobserver reliability. The Medical Outcomes Study 36-Item Short-Form Health Survey, Western Ontario and McMaster University Osteoarthritis Index, and the Harris hip score showed high validity and reliability. The Harris hip score can be used by a physician or a physiotherapist to study the clinical outcome of hip replacement.
Article
Objective. This study aimed to establish a basis of descriptive data for the sit-stand-sit movement cycle in 50 normal subjects, 25 male and 25 female, aged between 20.1 and 78.3 years (mean age 46.8 years).Design. A descriptive design was employed to establish the characteristics of the activity in normal subjects.Background. Research has been carried out into kinetic and kinematic characteristics of the sit-to-stand movement, but few researchers have considered stand-to-sit. Most studies have involved small samples, subjects with pathology, or elderly subjects, so a baseline of data from normal subjects has not yet been established.Method. Linear displacement and acceleration of the trunk and angular displacement of the knee were recorded simultaneously within the same temporal framework. The measurement system consisted of a vector stereograph, and triaxial accelerometers located at the level of C7, and an electrogoniometer located at the lateral aspect of the knee. Subjects rose from and descended to the seated position a total of six times at their own self-selected speed. Numerical data were subjected to descriptive analysis, matched-pairs t tests and Pearson's rho correlations.Results. Mean values for the time to rise was 1.91 s and to descend was 1.97 s. Forward lean velocity was greater during rising than descending (P < 0.001), and recovery velocity was greater during descending than rising (P < 0.001). Temporal contributions of forward lean and vertical displacement and the period of overlap between them were identified, and relationships between acceleration and temporal events and components were established. Differences existed among groups, involving primarily the elderly groups and occurring during the rising phase.Conclusions. This study has proposed a baseline of descriptive data in normal subjects for the sit-stand-sit movement cycle.
Article
After hip arthroplasty, many patients continue to exhibit abnormal gait patterns. The purpose of this study was to compare the vertical ground reaction forces of a group of 27 individuals who have undergone hip arthroplasty with a group of 35 normal control subjects. Specific force measures were determined from vertical ground reaction forces collected on a treadmill instrumented with two force plates. Symmetry indices were calculated on both groups of subjects. First and second peak forces, loading rate, impulse, and stance time were significantly less, while time to first peak force was significantly greater on the affected leg of the hip arthroplasty subjects when compared to their unaffected leg, or to the control group. The hip arthroplasty group showed greater asymmetry of ground reaction forces than the control group did. Bilateral asymmetric limb loading persists well after unilateral hip replacement surgery. Ground reaction force measures have been shown to be an effective means of quantifying the antalgic gait of hip arthroplasty patients.
Article
A method to calculate the complete ground reaction force (GRF) components from the vertical GRF measured with pressure insoles is presented and validated. With this approach it is possible to measure several consecutive steps without any constraint on foot placement and compute a standard inverse dynamics analysis with the estimated GRF.
Article
Total hip arthroplasty (THA) surgery is one of the most common orthopedic procedures performed on individuals with end-stage osteoarthritis of the hip. This study: () compared temporal spatial gait parameters and quality of life (QOL) scores of individuals with unilateral total hip arthroplasty (THA) to those of healthy older adults ages 65 to 85 years and (2) explored the relationship between the variables. Three dimensional motion analysis was used to calculate walking velocity, cadence, stride length, single support time, and double support time. All participants completed the Medical Outcome Survey Short Form 36 Health Survey (SF 36(R)) to measure health related QOL subscales. The individuals with THA walked slower (P = .005) with a longer double support phase (P = .02) and rated physical functioning (P < .0001 ) and role physical scores (P = .001 ) lower than the healthy older adults. For all subjects combined, a positive correlation was identified between walking velocity and physical functioning (P = .001 ), role-physical scores (P = .001 ) and bodily pain (P = .001 ); a negative correlation was identified between double support time and role physical score (P = .002) and bodily pain (P =.002). Individuals who undergo THA surgery have gait deficits that relate to physical subscales of the SF36(R). These findings provide guidance for physical therapy interventions focused on gait performance after THA.
Article
During stroke recovery, restoration of the paretic ankle and compensation in the non-paretic ankle may contribute to improved balance maintenance. We examine a new approach to disentangle these recovery mechanisms by objectively quantifying the contribution of each ankle to balance maintenance. Eight chronic hemiparetic patients were included. Balance responses were elicited by continuous random platform movements. We measured body sway and ground reaction forces below each foot to calculate corrective ankle torques in each leg. These measurements yielded the Frequency Response Function (FRF) of the stabilizing mechanisms, which expresses the amount and timing of the generated corrective torque in response to sway at the specified frequencies. The FRFs were used to calculate the relative contribution of the paretic and non-paretic ankle to the total amount of generated corrective torque to correct sway. All patients showed a clear asymmetry in the balance contribution in favor of the non-paretic ankle. Paretic balance contribution was significantly smaller than the contribution of the paretic leg to weight bearing, and did not show a clear relation with the contribution to weight bearing. In contrast, a group of healthy subjects instructed to distribute their weight asymmetrically showed a one-on-one relation between the contribution to weight bearing and to balance. We conclude that the presented approach objectively quantifies the contribution of each ankle to balance maintenance. Application of this method in longitudinal surveys of balance rehabilitation makes it possible to disentangle the different recovery mechanisms. Such insights will be critical for the development and evaluation of rehabilitation strategies.
Article
Currently, force plates or pressure sensitive insoles are the standard tools to measure ground reaction forces and centre of pressure data during human gait. Force plates, however, impose constraints on foot placement, and the available pressure sensitive insoles measure only one component of force. In this study, shoes instrumented with two force transducers measuring forces and moments in three dimensions were evaluated. Technical performance was assessed by comparing force measurement and centre of pressure reconstructions of the instrumented shoes against a force plate. The effect of the instrumented shoes on gait was investigated using an optical tracking system and a force plate. Instrumented shoes were compared against normal shoes and weighted shoes. The ground reaction force measured with force plate and instrumented shoes differed by 2.2+/-0.1% in magnitude and by 3.4+/-1.3 degrees in direction. The horizontal components differed by 9.9+/-3.8% in magnitude and 26.9+/-10.0 degrees in direction. Centre of pressure location differed by 13.7+/-2.4mm between measurement systems. A MANOVA repeated measures analysis on data of seven subjects, revealed significant differences in gait pattern between shoe types (p</=0.05). A subsequent univariate analysis showed significant differences only in maximum ground reaction force but these could not be attributed to specific shoe types by pair-wise comparison. This study indicates that shoes instrumented with force transducers can be a valuable alternative to current measurement systems if accurate sensing of position and orientation of the force transducers is improved. They are applicable in ambulatory settings and suitable for inverse dynamics analysis.
Article
Although literature in relation to rising to stand from a chair is extensive, there is limited information on symmetry and motion in the frontal and transverse planes. Ground reaction forces (GRF), lower limb angular displacements and moments, and the thoracolumbar and cervicothoracic spine regions angular displacements around the vertical and antero-posterior axes (respectively, the transverse and frontal planes) were investigated in 12 females. Right to left symmetry and the trial-to-trial consistency of all variables was also investigated. Able-bodied participants demonstrated frontal and transverse plane displacement and moments in the lower limbs and the trunk, and mediolateral GRFs, during rising to stand from a chair. The results of this study also support the concept of a consistent individual strategy for frontal plane motion during rising to stand and highlight the strategies used to maintain side-to-side stability during the motion. The potential importance of this was reflected in the similar magnitudes of the GRFs required to stabilise the median plane orientation of the centre of mass and that required for the forward propulsion of the body. Asymmetrical net applied moments support the concept of side dominance in components of apparently symmetrical motor tasks.
Article
Patients with standard total hip arthroplasties may have reduced hip abduction and extension moments when compared with normal nonosteoarthritic hips. In comparison, patients after resurfacing total hip arthroplasty appear to have a near-normal gait. The authors evaluated temporal-spatial parameters, hip kinematics, and kinetics in hip resurfacing patients compared with patients with unilateral osteoarthritic hips and unilateral standard total hip arthroplasties. Patients with resurfacing walked faster (average 1.26 m/s) and were comparable with normals. There were no significant differences in hip abductor and extensor moments of patients with resurfacing compared with patients in the standard hip arthroplasty group. This study showed more normal hip kinematics and functionality in resurfacing hip arthroplasty, which may be due to the large femoral head.
Biomecanica y bases neuromusculares de la actividad fisica y deporte Spain, Médica Panamericana
  • M Izquierdo
M. Izquierdo, Biomecanica y bases neuromusculares de la actividad fisica y deporte Spain, Médica Panamericana, 2008, ch. 10, pp. 177–181.
Biomecanica y bases neuromusculares de la actividadfisica y deporte
  • M Izquierdo