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1994 Nicola Cerulli Young Researchers Award. Downhill walking: a stressful task for the anterior cruciate ligament? A biomechanical study with clinical implications

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1994 Nicola Cerulli Young Researchers Award. Downhill walking: a stressful task for the anterior cruciate ligament? A biomechanical study with clinical implications

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Abstract

Accelerated rehabilitation after anterior cruciate ligament (ACL) reconstruction has become increasingly popular. Methods employed include immediate extension of the knee and immediate full weight bearing despite the risks presented by a graft pull-out fixation strength of 200-500 N. The purpose of this study was to calculate the tibiofemoral shear forces and the dynamic stabilising factors at the knee joint for the reasonably demanding task of downhill walking, in order to determine whether or not this task presented a postoperative risk to the patient. Kinematic and kinetic data were collected on six male and six female healthy subjects during downhill walking on a ramp with a 19% gradient. Planar net joint moments and mechanical power at the knee joint were calculated for the sagittal view using a force platform and videographic records together with standard inverse dynamics procedures. A two-dimensional knee joint model was then utilised to calculate the tibiofemoral shear and compressive forces, based on the predictions of joint reaction force and net moment at the knee. Linear envelopes of the electromyographic (EMG) activity recorded from the rectus femoris, gastrocnemius and biceps femoris muscles were also obtained. The maximum tibiofemoral shear force occurred at 20% of stance phase and was, on average, 1.2 times body weight (BW) for male subjects and 1.7 times BW for female subjects. The tibiofemoral compressive force was 7 times BW for males and 8.5 times BW for females during downhill walking. The hamstring muscle showed almost continuous activity throughout the whole of the stance phase.(ABSTRACT TRUNCATED AT 250 WORDS)

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... The tibiofemoral joint shear forces (F S ) during the deceleration task were then calculated from the net joint reaction forces and the patellar tendon force occasioned by the net moments and inertial forces predicted to be acting about the knee [27]. This method was selected in preference to the traditional approach of Nisell [28] because the accelerations of body segments and the intersegmental eects between the leg and foot were taken into account [27]. ...
... The tibiofemoral joint shear forces (F S ) during the deceleration task were then calculated from the net joint reaction forces and the patellar tendon force occasioned by the net moments and inertial forces predicted to be acting about the knee [27]. This method was selected in preference to the traditional approach of Nisell [28] because the accelerations of body segments and the intersegmental eects between the leg and foot were taken into account [27]. Biomechanical data reported by Nisell [28] were used to model knee joint musculoskeletal geometry in calculating the F S (see Fig. 1). ...
... As anticipated, the F S generated during the dynamic deceleration task were higher than peak F S reported for various walking modes [27] and during more vertically directed hopping, stepping and jumping tasks [11,29]. These ®ndings con®rmed the notion that abrupt deceleration tasks are stressful tasks which create high anterior loading at the tibiofemoral joint. ...
Article
This study examined the influence of chronic anterior cruciate ligament deficiency on muscle activation patterns displayed during abrupt deceleration, relative to timing of tibiofemoral shear forces (Fs) generated during the task. Experimental data were collected for both limbs of 11 chronic functional anterior cruciate ligament deficient subjects and 11 matched controls. Electromyographic, high speed film and ground reaction force data were sampled as subjects landed in single-limb stance on a force platform after receiving a chest level pass and decelerating abruptly. Temporal characteristics of each muscle burst relative to initial foot-ground contact were derived and Fs were calculated from net joint reaction forces and the patellar tendon force occasioned by the net moments and inertial forces predicted about the knee. Compared to controls, anterior cruciate ligament deficient subjects displayed a delay in hamstring activation so that peak hamstring activity was more synchronous with initial contact and with the high Fs which occurred after initial contact. It was concluded the delayed hamstring activation was an adaptation developed to enable peak muscle activity to better coincide with the high anterior Fs, thereby stabilizing the injured limb against a giving-way episode via increased joint compression and posterior tibial drawer.
... During downhill walking joint moments at the knee, and to a lesser extent the ankle and hip, were affected by the inclination. Knee extension moments showed large increases with increased inclination [4,6] and there is evidence that the anterior cruciate ligament is highly loaded during downhill walking [7]. During uphill walking, an increased hip extensor moment occurs with increasing inclination [3,4]. ...
... To analyze a non-impaired population, musculoskeletal models are commonly used to calculate joint loadings [10]. While early studies estimated knee joint forces using 2D-analyses [5,7], recent models can predict 3D muscle and joint forces by employing more complex quasi-static or dynamic optimization techniques [8,12,13]. ...
... Several studies analysed lower limb joint forces using musculoskeletal models during level walking [9,14,15], while for sloped walking, the number of studies has been limited [5,7,8]. The available studies on sloped walking only provide limited information. ...
... Depending on the task analyzed, tibiofemoral contact point in ACL-D knees were more posterior in both the medial and lateral compartments [25], or more posterior only in the medial compartment [20], or more posterior in the medial compartment and more anterior in the lateral compartment [8]. Due to the importance of the ACL in high impact dynamic activities, it may be more appropriate to analyze kinematics of ACL-deficient knees during dynamic weight-bearing activities in ranges of knee motion closer to extension where the ACL plays a greater role in stability [19,38]. Importantly, previous biplane fluoroscopic studies of ACL-D knees studied pre-surgical patients who reported instability after ACL-injury, rather than chronic ACL-D knees with no reports of instability. ...
... The treadmill provided a 10° downward slope during the downhill running test. The task of downhill running was included because it is relatively stressful on the ACL but can be performed in a controlled, repeatable fashion within the laboratory environment and is unlikely to put the individual at significant risk for injury [19]. ...
Article
PurposeTo analyze the in vivo kinematics and arthrokinematics of chronic ACL-deficient (ACL-D) and unaffected contralateral knees during level walking and downhill running using dynamic biplane radiography. It was hypothesized that ACL-D knees would demonstrate increased anterior translation and internal rotation, and that ACL-deficiency would alter the tibiofemoral contact paths in comparison to the unaffected contralateral side. Methods Eight participants with unilateral chronic ACL-D without instability symptoms were recruited. The contralateral unaffected knee was considered as control. Kellgren–Lawrence (K–L) grades were determined from ACL-D and unaffected knees. Dynamic knee motion was determined from footstrike through the early-stance phase (20–25% of gait cycle) using a validated volumetric model-based tracking process that matched subject-specific CT bone models to dynamic biplane radiographs. Participants performed level walking at 1.2 m/s and downhill running at 2.5 m/s while biplane radiographs were collected at 100 and 150 images per second, respectively. Tibiofemoral kinematics and arthrokinematics (the path of the closest contact point between articulating subchondral bone surfaces) were determined and compared between ACL-D and unaffected knees. A two-way repeated measures analysis of variance was used to identify differences between ACL-D and unaffected knees at 5% increments of the gait cycle. ResultsAnterior–posterior translations were significantly larger in ACL-D than unaffected knees during level walking (all p < 0.001) and downhill running (all p ≤ 0.022). Internal rotation showed no significant difference between ACL-D and unaffected knees during level walking and downhill running. Closest contact points on the femur in ACL-D knees were consistently more anterior in the lateral compartment during downhill running (significant from 10 to 20% of the gait cycle, all p ≤ 0.044), but not during level walking. No differences in medial compartment contact paths were identified. Half of the participants had asymmetric K–L grades, with all having worse knee OA in the involved knee. Only 2 relatively young individuals had not progressed beyond stage 1 in either knee. Conclusion The results suggest that anterior translation and knee joint contact paths are altered in ACL-D knees even in the absence of instability symptoms. The clinical relevance is that ACL-D patients who do not report symptoms of instability likely still demonstrate altered knee kinematics and arthrokinematics compared to their uninvolved limb. Level of evidenceCase–control study, Level III.
... The second purpose of this study was to compare two estimation methods of PTF. During a human movement, any flexor moment produced by the hamstrings or gastrocnemius must be compensated by higher knee extensor moments [18]. As the inverse dynamic method does not consider muscle co-contractions, we supposed that the estimation of PTF will be lower for the inverse dynamic method compared to the static optimization method [19]. ...
Article
Full-text available
Patellar tendinopathy is a chronic overuse injury of the patellar tendon which is prevalent in jump-landing activities. Sports activities can require jumping not only with a vertical component but also in a forward direction. It is yet unknown how jumping in the forward direction may affect patellar tendon forces. The main purpose of this study was to compare PTF between landings preceded by a vertical jump and a forward jump in volleyball players. The second purpose was to compare two different estimation methods of the patellar tendon force. Fifteen male volleyball players performed vertical and forward jump-landing tasks at a controlled jump height, while kinetics and kinematics were recorded. Patellar tendon forces were calculated through two estimation methods based on inverse dynamic and static optimization procedures, using a musculoskeletal model. Results showed that forward jump-landing generated higher patellar tendon forces compared to vertical jump-landing for both estimation methods. Surprisingly, although the static optimization method considered muscle co-contraction, the inverse kinematic method provided statistically significant higher patellar tendon force values. These findings highlight that limiting the forward velocity component of the aerial phase appears to reduce the load on the patellar tendon during landing and may help to prevent patellar tendinopathy.
... It has been reported that the number of military personnel in the United States Army, Navy, and Air Force who undergo surgery to reconstruct a torn Anterior cruciate ligament (ACL) exceeds 2500 per year [10]. Kuster et al. reported that walking downhill carries a higher risk of injury to the non-contact ACL than walking over level ground [11]. However, a limitation of their study was that they examined only one factor (the anterior shear force) out of the many possible risk factors for ACL injuries. ...
Article
We investigated 3D kinematic and kinetic changes of knee and ankle during downhill walking as the slope angle increased and evaluated biomechanical injury risk factors related to non-contact ACL injury. Fifteen male subjects performed level walking and 15° and 25° downhill walking. For the kinetic and kinematic parameters, one-way ANOVA and post-hoc tests were performed at a significance level of 0.05. This study revealed significant differences in 3D knee and ankle kinematics and kinetics among 0°, 15° and 25° downhill walking. The peak posterior ground reaction force, the peak knee anterior force and the knee valgus moment (0° vs. 15°: p < 0.05; 0° vs. 25°: p < 0.05) in the early stance phase increased as the slope angle increased. The peak knee internal tibial rotation moments in the late stance also increased (0° vs. 15°: p < 0.05; 0° vs. 25°: p < 0.05; 15° and 25°: p < 0.05) as the slope angle increased. These results showed the risk for ACL injuries may be increased during downhill walking with a greater slope angle.
... The ground reaction force data and kinematic data were initially synchronised using the common event marker (LED pulse) and the film frame representing IC to ensure correct correspondence between the kinetic and kinematic data. The tibiofemoral joint shear forces (F S ) during the deceleration task were then estimated from the net joint reaction forces and the patellar tendon force occasioned by the net moments and inertial forces predicted to be acting about the knee [17]. Further details of this method are discussed by Steele and Brown [18]. ...
Article
This study examined whether lower limb muscle synchrony during abrupt landings was affected by gender, thereby predisposing females to a higher incidence of non-contact anterior cruciate ligament (ACL) injuries than males. Seven males and 11 females landed in single-limb stance on a force platform after receiving a chest-height netball pass and decelerating abruptly. Ground reaction force and electromyographic data for rectus femoris, vastus lateralis, vastus medialis, semimembranosus (SM), biceps femoris, and gastrocnemius were sampled (1000 Hz) during landing. Subjects' sagittal plane motion was also filmed (200 Hz). Knee joint reaction forces and sagittal planar net moments of force were estimated using Newtonian equations of motion and inverse dynamics. Tibiofemoral shear forces (F(s)) were obtained and muscle bursts temporally analysed with respect to initial foot-ground contact (IC) and peak F(s) times. Males displayed significantly delayed SM onset relative to IC (113+/-46 ms) compared to females (173+/-54 ms; p=0.03), and significantly delayed SM peak activity relative to peak F(s) (54+/-27 ms) compared to females (77+/-15 ms; p=0.03). Delayed SM activity during landing was suggested to allow peak muscle activity to better coincide with high anterior F(s), thereby acting as an ACL synergist via increased joint compression and posterior tibial drawer. It was concluded that females displayed muscle synchrony less protective of the ACL than males, possibly increasing their susceptibility to non-contact ACL injuries.
... Kuster et al. (1995) reported significantly increased peak ground reaction forces (+38%), peak knee flexion moments (+117%) and peak knee muscle power (+490%) during downhill walking at a decline of 11° compared with level walking. These results indicate that downhill walking is stressful for different knee joint structures (Kuster et al., 1994). ...
Article
Full-text available
The aim of this study was to determine external and internal loads on the knee joint during downhill walking with and without hiking poles. Kinematic, kinetic and electromyographic data were collected from eight males during downhill walking on a ramp declined at 25 degrees. Planar knee joint moments and forces were calculated using a quasi-static knee model. The results were analysed for an entire pole-cycle as well as differentiated between single and double support phases and between each step of a pole-cycle. Significant differences between downhill walking with and without hiking poles were observed for peak and average magnitudes of ground reaction force, knee joint moment, and tibiofemoral compressive and shear forces (12-25%). Similar reductions were found in patellofemoral compressive force, the quadriceps tendon force and the activity of the vastus lateralis; however, because of a high variability, these differences were not significant. The reductions seen during downhill walking with hiking poles compared with unsupported downhill walking were caused primarily by the forces applied to the hiking poles and by a change in posture to a more forward leaning position of the upper body, with the effect of reducing the knee moment arm.
... We also acknowledge that the net knee joint moment was used to estimate patellar tendon force, which may have lead to an underestimation of the patellar tendon force. That is, any flexor moment produced by the hamstrings or gastrocnemius must be compensated by higher knee extensor moments, which was not reflected in the net knee moment calculation (Kuster et al., 1994). We recommend further research be conducted to address these limitations by developing a three-dimensional patellar tendon model that can be implemented in future studies to confirm our findings. ...
Article
Excessive extensor mechanism loading from repeated landing has been associated with overuse knee injuries, especially patellar tendinopathy. In order to reduce these loads, it is important to establish which landing task places the highest load on the patellar tendon. It was hypothesized that the horizontal landing would create higher patellar tendon force (F(PT)) compared with the vertical landing. Sixteen male athletes with healthy patellar tendons performed five successful trials of a stop-jump task, which involved a symmetrical two-foot landing after a horizontal approach (horizontal landing) followed by another symmetrical two-foot landing after a vertical jump (vertical landing). For both lower limbs during each trial, the participants' ground reaction forces were recorded, three-dimensional kinematics measured and F(PT) calculated by dividing the net knee joint moment by the patellar tendon moment arm. Compared with the vertical landing, significantly higher F(PT), posterior ground reaction forces and F(PT) loading rates were generated during the horizontal landing, despite lower vertical ground reaction forces (F(V)), highlighting the notion that F(V) should not be used to reflect F(PT). Understanding that a horizontal landing task places the highest load on the patellar tendon, provides an appropriate framework for future research to investigate lower limb landing strategies in athletes with patellar tendinopathy.
... At the most basic level the description of the musculoskeletal system can be contracted to reduce the system to a determinate one by reducing the number of muscle elements or by grouping like muscular elements by function. This is an approach that was frequently employed in early musculoskeletal modelling studies 62,[77][78][79][80][81][82][83] and studies of open chain knee function, 84,85 but is still employed in contemporary clinical studies. [86][87][88][89] Although this approach does make the solution of the equations of motion almost trivial, the loss in fidelity of the model is likely to significantly affect the validity or clinical relevance of the model outputs. ...
Article
Full-text available
Contemporary musculoskeletal modelling research is based upon the assumption that such models will evolve into clinical tools that can be used to guide therapeutic interventions. However, there are a number of questions that must be addressed before this becomes a reality. At its heart, musculoskeletal modelling is a process of formulating and then solving the equations of motion that describe the movement of body segments. Both of these steps are challenging. This article argues that traditional approaches to musculoskeletal modelling have been heavily influenced by the need to simplify this process (and in particular the solution process), and that this has to some degree resulted in approaches that are contrary to the principles of classical mechanics. It is suggested that future work is required to understand how these simplifications affect the outputs of musculoskeletal modelling studies. Equally, to increase their clinical relevance, the models of the future should adhere more closely to the classical mechanics on which they are based.
... The two-dimensional model used to estimate patellar tendon force would underestimate the patellar tendon force because it uses the net knee joint moment to estimate patellar tendon force. This calculation does not account for the flexor moment produced by the hamstring or gastrocnemius muscles, which must be compensated for by a higher knee extensor moment (24), or the different anthropometry of each participant's patellar tendon moment arm, which was not scaled. It has been suggested that the patellar tendon should be modeled three-dimensionally owing to its orientation in the sagittal and coronal planes. ...
Article
When investigating lower limb landing biomechanics, researchers often assume movement symmetry between a participant's right and left lower limbs for the simplicity of data collection and analysis, although landing tasks often involve dual-limb motion. However, whether lower limb symmetry can be assumed when investigating dynamic, sport-specific movements such as the stop-jump has not been investigated. Therefore, this study aimed to determine whether there were any significant differences in selected kinetic, kinematic, and muscle activation patterns characterizing lower limb biomechanics displayed by the dominant limb compared with the nondominant limb of participants during a stop-jump task. Sixteen male athletes with normal patellar tendons on diagnostic imaging performed five successful stop-jump trials. Patellar tendon forces (FPT), ground reaction forces, three-dimensional kinematics, and EMG activity of seven lower limb muscles were recorded for the dominant and nondominant lower limbs during each trial. During the horizontal landing phase, the dominant lower limb sustained a significantly higher FPT and peak net knee joint extension moment compared with the nondominant lower limb. Furthermore, during the vertical landing phase, the dominant lower limb sustained significantly lower vertical but higher posterior ground reaction forces compared with the nondominant lower limb. Other variables did not significantly vary as a function of lower limb dominance. It is recommended that researchers clearly identify their primary outcome variables and ensure that their experimental design, particularly in terms of lower limb dominance, provides an appropriate framework to investigate possible mechanics underlying unilateral and bilateral knee joint injuries during dual-limb movements such as the stop-jump task.
... The patients performed moderate-speed running (2.5 m/ second) on an instrumented dual-belt treadmill (Bertec Corp, Columbus, OH, USA) with a 10°downward slope (Fig. 2). We selected downhill running for the testing activity because it generates greater shear stress on the knee [25] and has been used previously to identify abnormal knee kinematics after conventional SB reconstruction [32,33]. We collected three trials for each limb of each patient. ...
Article
Background: Rotational kinematics has become an important consideration after ACL reconstruction because of its possible influence on knee degeneration. However, it remains unknown whether ACL reconstruction can restore both rotational kinematics and normal joint contact patterns, especially during functional activities. Questions/purposes: We asked whether knee kinematics (tibial anterior translation and axial rotation) and joint contact mechanics (tibiofemoral sliding distance) would be restored by double-bundle (DB) or single-bundle (SB) reconstruction. Methods: We retrospectively studied 17 patients who underwent ACL reconstruction by the SB (n = 7) or DB (n = 10) procedure. We used dynamic stereo x-ray to capture biplane radiographic images of the knee during downhill treadmill running. Tibial anterior translation, axial rotation, and joint sliding distance in the medial and lateral compartments were compared between reconstructed and contralateral knees in both SB and DB groups. Results: We observed reduced anterior tibial translation and increased knee rotation in the reconstructed knees compared to the contralateral knees in both SB and DB groups. The mean joint sliding distance on the medial compartment was larger in the reconstructed knees than in the contralateral knees for both the SB group (9.5 ± 3.9 mm versus 7.5 ± 4.3 mm) and the DB group (11.1 ± 1.3 mm versus 7.9 ± 3.8 mm). Conclusions: Neither ACL reconstruction procedure restored normal knee kinematics or medial joint sliding. Clinical relevance: Further study is necessary to understand the clinical significance of abnormal joint contact, identify the responsible mechanisms, and optimize reconstruction procedures for restoring normal joint mechanics after ACL injury.
... Kuster et al. (1995) reported significantly increased peak ground reaction forces (+38%), peak knee flexion moments (+117%) and peak knee muscle power (+490%) during downhill walking at a decline of 11° compared with level walking. These results indicate that downhill walking is stressful for different knee joint structures (Kuster et al., 1994). ...
... The two-dimensional model used to estimate patellar tendon force would underestimate the patellar tendon force because it uses the net knee joint moment to estimate patellar tendon force. This calculation does not account for the flexor moment produced by the hamstring or gastrocnemius muscles, which must be compensated for by a higher knee extensor moment (24), or the different anthropometry of each participant's patellar tendon moment arm, which was not scaled. It has been suggested that the patellar tendon should be modeled three-dimensionally owing to its orientation in the sagittal and coronal planes. ...
... 15 There is also evidence that the anterior cruciate ligament is heavily loaded during downhill walking. 11,16 Inclined walking is associated with an increase of lower extremity joint loading compared with level walking. 10,17 During downhill walking, joint moments at the knee and, to a lesser extent, the ankle and hip, can be affected by inclination, with knee extension moments showing large increases relative to increased downward inclination. ...
Article
While inclined walking is a frequent daily activity, muscle forces during this activity have been rarely examined. Musculoskeletal models are commonly used to estimate internal forces in healthy populations, but these require a priori validation. The aim of this study was to compare estimated muscle activity using a musculoskeletal model with measured EMG data during inclined walking. Ten healthy male participants walked at different inclinations of 0°, +/-6°, +/-12° and +/-18° on a ramp equipped with two force plates. Kinematics, kinetics and muscle activity of m. biceps femoris, m. rectus femoris, m. vastus lateralis, m. tibialis anterior and m. gastrocnemius lateralis were recorded. Agreement between estimated and measured muscle activity was determined via correlation coefficients, mean absolute errors and trend analysis. Correlation coefficients between estimated and measured muscle activity for approximately 69% of the conditions were above 0.7. Mean absolute errors were rather high with only approximately 38% being ≤ 30%. Trend analysis revealed similar estimated and measured muscle activities for all muscles and tasks (uphill and downhill walking), except of m. tibialis anterior during uphill walking. This model can be used for further analysis in similar groups of participants.
... In general, TFJ compression force patterns and magnitudes were in line with results of ACL patients (Gardinier et al., 2013;Sanford et al., 2013), healthy populations (Sritharan, Lin, & Pandy, 2012;Worsley, Stokes, & Taylor, 2011) and in vivomeasurements (Kutzner, Heinlein, Graichen, Bender, Rohlmann, Halder et al., 2010). TFJ shear force patterns are in agreement with those of ACL reconstructed patients using musculoskeletal modelling (Sanford et al., 2013) and with the patterns measured in vivofrom patients with an knee implant due to osteoarthritis (Kutzner et al., 2010), but are contradictory with results using static equilibrium modelling approaches (Kuster, Wood, Sakurai, & Blatter, 1994;Shelburne, Torry, & Pandy, 2005). Muscle force patterns were also in line with results of ACL patients (Gardinier et al., 2013;Sanford et al., 2013). ...
Conference Paper
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The purpose of this study was to analyse the acute effects of the manual therapy RegentK on tibiofemoral joint forces and lower limb muscle forces in patients with an acute unilateral ACL rupture. Eight patients with an acute ACL rupture were recruited. Tibiofemoral joint forces and quadriceps, hamstring and gastrocnemius muscle forces were analysed during walking pre and immediately post the one time intervention using a musculoskeletal model.Results showed that tibiofemoral joint loading and muscle forces were altered in the injured compared to the uninjured limb, but no significant effect of the intervention could be shown. Joint and muscle force patterns, however, were highly individual. For future analyses the comparison with a matched-control group and the use of different methods to detect waveform-changes are recommended.
... To this end, downhill walking has been suggested to be more demanding on the knee joint compared to level gait, as it leads to significant increases in knee flexion angle, vertical ground reaction force and knee joint moments. [30][31][32][33] Given that downhill walking also challenges knee joint stability and lower extremity muscle strength, 31,34 it represents a reasonable model for assessing knee joint biomechanics during high-demanding daily tasks such as going up or down stairs. 35 Additionally, a relatively slow gait velocity of 0.75 m/s was chosen for our experimental set up based on the result of our pilot testing demonstrating that most patients with knee OA were unable to walk downhill at higher speeds. ...
Article
Full-text available
Objective: The objective of this exploratory study was to evaluate tibiofemoral joint contact point excursions and velocities during downhill gait and assess the relationship between tibiofemoral joint contact mechanics with frontal-plane knee joint motion and lower extremity muscle weakness in patients with knee osteoarthritis (OA). Methods: Dynamic stereo X-ray was used to quantify tibiofemoral joint contact mechanics and frontal-plane motion during the loading response phase of downhill gait in 11 patients with knee OA and 11 control volunteers. Quantitative testing of the quadriceps and the hip abductor muscles was also performed. Results: Patients with knee OA demonstrated larger medial/lateral joint contact point excursions (p < 0.02) and greater heel-strike joint contact point velocities (p < 0.05) for the medial and lateral compartments compared to the control group. The peak medial/lateral joint contact point velocity of the medial compartment was also greater for patients with knee OA compared to their control counterparts (p = 0.02). Additionally, patients with knee OA demonstrated significantly increased frontal-plane varus motion excursions (p < 0.01) and greater quadriceps and hip abductor muscle weakness (p = 0.03). In general, increased joint contact point excursions and velocities in patients with knee OA were linearly associated with greater frontal-plane varus motion excursions (p < 0.04) but not with quadriceps or hip abductor strength. Conclusion: Altered contact mechanics in patients with knee OA may be related to compromised frontal-plane joint stability but not with deficits in muscle strength.
... The anterior cruciate ligament (ACL) has documented proprioceptive function [26], and deficiency is known to cause walking difficulty especially when going downhill [18,27]. So the measurement of this task appears appropriate to determine whether functional deficits or advantages exist between procedures that sacrifice or preserve the ACL [16]. ...
Article
Purpose: To determine whether downhill walking gait pattern discriminates between different types of knee arthroplasty. Methods: Nineteen unicompartmental knee arthroplasty (UKA) and fourteen total knee arthroplasty (TKA) patients who were well matched demographically and with high Oxford knee scores (OKS) for their operation type were evaluated at a minimum 1 year after their operation with downhill gait analysis. Nineteen healthy young subjects were used as controls. Downhill gait analysis was carried out on an instrumented treadmill that was ramped at the rear to produce a declination of 7°. All subjects after a period of habituation were tested for preferred and top downhill walking speed with associated ground reaction and temporospatial measurements. Results: The UKA group had higher mean OKS (44.8 ± 2.9 vs 41.9 ± 4.7, p = 0.03) as predicted. The UKA group walked downhill 15% faster than the TKA group (1.75 ± 0.14 vs 1.52 ± 0.13 m/s, p < 0.0001) despite having the same cadence (134.9 ± 8.0 vs 133.9 ± 9.6 steps/min). This 15% difference in speed appeared largely due to a 15% increase in stride length (173 ± 14 vs 150 ± 17 cm, p = 0.0007) and normal weight acceptance, both of which were similar to the controls. Conclusion: Using an instrumented treadmill to test a commonly performed task, stride length when walking downhill highlights the functional differences between arthroplasty groups. Near normal restoration of physiological gait pattern was found in unicompartmentals as compared to total knee replacements. Level of evidence: Retrospective comparative study, Level III.
... Our simulations also resulted in knee joint compressive forces of 7.37 and 6.49 N/BW in the ACLd and ACLr state, respectively. Other modelling studies have quantified tibiofemoral compressive forces to range between 3.46 -9.92 N/BW depending on the task and population(32)(33)(34). Instrumented knee implants have also provided valuable data with respect to knee joint loading as of late. ...
Article
Purpose: Although basic objective measures (e.g. knee laxity, strength, hop tests) have been related to subjective measures of function, associations between knee-specific objective and subjective measures have yet to be completed. The objective was to determine if knee joint contact and ligament forces differ between pre and post-ACL reconstructed states and if these forces relate to their patient's respective subjective functional ability scores. Methods: Twelve patients performed a hopping task pre and post-reconstruction. Magnetic resonance images and OpenSim were used to develop patient-specific models in static optimization and joint reaction analyses. Questionnaires concerning each patient's subjective functional ability were also collected and correlated to knee joint contact and ligament forces. Results: No significant differences were observed between deficient and reconstructed groups with respect to knee joint contact or ligament forces. Nevertheless, there were several significant (p < 0.05) moderate to strong correlations between subjective and objective measures including Tegner activity level to contact force in both states (r = 0.67 - 0.76) and IKDC (International Knee Documentation Committee) to compressive and anterior shear forces (r = 0.64 - 0.66). Conclusion: Knee-specific objective measures of a patient's functional capacity can represent their subjective ability, which explains this relationship to a greater extent than past anatomical and gross objective measures of function. This consolidation is imperative for improving the current rehabilitation schema as it allows for external validation of objective and subjective functional measures. With poor validation of subjective function against objective measures of function, the re-injury rate is unlikely to diminish, continuing the heavy financial burden on healthcare systems.Key Terms: Knee, Musculoskeletal modelling, Rehabilitation, patient-specific.
... The anterior cruciate ligament (ACL) has documented restraint and proprioceptive function (75) and deficiency is known to cause walking difficulty especially when going downhill (76,77). So the measurement of this task appears appropriate to determine if functional deficits or advantages exist between procedures that sacrifice or preserve the ACL (78). ...
... To analyze a non-impaired population, musculoskeletal models are commonly used to calculate joint loadings (Erdemir et al., 2007). While early studies estimated knee joint forces using 2D-analyses (Schwameder et al., 2005;Kuster et al., 1994), recent models can predict 3D muscle and joint forces by employing more complex quasi-static or dynamic optimization techniques (Haight et al., 2014;Sanford et al., 2013;Dorn et al., 2015). These methodologies have been applied to study the lower extremity joint loading in diverse settings while walking on inclined surfaces. ...
Conference Paper
Full-text available
Moving on slopes is part of daily living locomotion, but also several sport disciplines are performed on inclined terrain. From a biomechanical perspective locomotion on slopes is a challenging task as additional work has to be done compared to locomotion on flat terrain. Moving downwards supports the locomotion due to gravity, however, steep slopes often lead to high speeds caused by the transfer of potential to kinetic energy. Then locomotion is accompanied with the challenge to control speed. Another issue is the aspect of joint loading when moving on slopes. An increase of potential or kinetic energy is associated with an enhancement of work done by the joint structures. The purpose of the presentation is to characterize the specificity and challenges when moving on slopes from a biomechanical perspective including performance, coordination, safety and joint loading in daily movement and sport related tasks.
... The patients were allowed to warm up and become familiar with running on the treadmill for about 30 seconds before data collection. Moderate-speed downhill running was selected as the activity for this study because it is more stressful on the ACL than level-ground running 31 and follows our previously established protocol. 46 In addition to placing greater mechanical demands on the knee than walking, running eliminates the double-support phase and reduces the effects of compensation from the contralateral limb. ...
Article
Background: Anterior cruciate ligament reconstruction (ACLR) has been shown to alter kinematics, which may influence dynamic tibiofemoral joint congruency (a measure of how well the bone surfaces fit together). This may lead to abnormal loading of cartilage and joint degeneration. However, joint congruency after ACLR has never been investigated. Hypotheses: The ACLR knee will be more congruent than the contralateral uninjured knee, and dynamic congruency will increase over time after ACLR. Side-to-side differences (SSD) in dynamic congruency will be related to cartilage contact location/area and subchondral bone curvatures. Study design: Descriptive laboratory study. Methods: The authors examined 43 patients who underwent unilateral ACLR. At 6 months and 24 months after ACLR, patients performed downhill running on a treadmill while synchronized biplane radiographs were acquired at 150 images per second. Dynamic tibiofemoral kinematic values were determined by use of a validated volumetric model-based tracking process that matched patient-specific bone models, obtained from computed tomography, to biplane radiographs. Patient-specific cartilage models, obtained from magnetic resonance imaging, were registered to tracked bone models and used to calculate dynamic cartilage contact regions. Principle curvatures of the subchondral bone surfaces under each cartilage contact area were calculated to determine joint congruency. Repeated-measures analysis of variance was used to test the differences. Multiple linear regression was used to identify associations between SSD in congruency index, cartilage contact area, contact location, and global curvatures of femoral or tibial subchondral bone. Results: Lateral compartment congruency in the ACLR knee was greater than in the contralateral knee ( P < .001 at 6 months and P = .010 at 24 months). From 6 to 24 months after surgery, dynamic congruency decreased in the medial compartment ( P = .002) and increased in the lateral compartment ( P = .007) in the ACLR knee. In the lateral compartment, SSD in joint congruency was related to contact location and femur global curvature, and in the medial compartment, SSD in joint congruency was related to contact area. Conclusion: ACLR appears to affect dynamic joint congruency. SSD in joint congruency was associated with changes in contact location, contact area, and femoral bony curvature. Clinical relevance: Alterations in tibiofemoral contact location, contact area, and bone shape affect dynamic joint congruency, potentially contributing to long-term degeneration after ACLR.
... Electromyographic activity, recorded from our subjects during their downhill walking, clearly indicated the presence of hamstring, gastrocnemius and quadriceps muscle co-activity during the stance phase. 19 The measures of joint compression reported here are therefore conservative estimates but still exceed eight times bodyweight for downhill walking. Force values equivalent to three to four times BW have previously been used in most biomechanical tests evaluat-ing total knee replacements. ...
Article
Full-text available
Estimates of knee joint loadings were calculated for 12 normal subjects from kinematic and kinetic measures obtained during both level and downhill walking. The maximum tibiofemoral compressive force reached an average load of 3.9 times body-weight (BW) for level walking and 8 times BW for downhill walking, in each instance during the early stance phase. Muscle forces contributed 80% of the maximum bone-on-bone force during downhill walking and 70% during level walking whereas the ground reaction forces contributed only 20% and 30% respectively. Most total knee designs provide a tibiofemoral contact area of 100 to 300 mm ² . The yield point of these polyethylene inlays will therefore be exceeded with each step during downhill walking. Future evaluation of total knee designs should be based on a tibiofemoral joint load of 3.5 times BW at 20° knee flexion, 8 times BW at 40° and 6 times BW at 60°.
... Decline walking was selected as the movement activity for the study. This activity is considered to be modestly stressful and demanding on the knee and can elicit higher levels of shear and compressive forces and activations/co-activations of some muscles than walking on flat ground [41] . A recent study of the meniscal root tear effects on joint kinematics [42] confirmed that more pronounced differences between injured and intact knees were observed during decline walking as compared to level walking. ...
Article
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We investigated the effects of isolated meniscectomy on tibiofemoral skeletal kinematics and cartilage contact arthrokinematics in vivo. We recruited nine patients who had undergone isolated medial or lateral meniscectomy, and used a dynamic stereo-radiography (DSX) system to image the patients' knee motion during decline walking. A volumetric model-based tracking process determined 3D tibiofemoral kinematics from the recorded DSX images. Cartilage contact arthrokinematics was derived from the intersection between tibial and femoral cartilage models co-registered to the bones. The kinematics and arthrokinematics were analyzed for early stance and loading response phase (30% of a gait cycle), comparing the affected and intact knees. Results showed that four patients with medial meniscectomy had significantly greater contact centroid excursions in the meniscectomized medial compartments while five patients with lateral meniscectomy had significantly greater cartilage contact area and lateral shift of contact centroid path in the meniscectomized lateral compartments, comparing to those of the same compartments in the contralateral intact knees. No consistent difference however was identified in the skeletal kinematics. The current study demonstrated that cartilage-based intra-articular arthrokinematics is more sensitive and insightful than the skeletal kinematics in assessing the meniscectomy effects.
Article
A high prevalence of rupture of the anterior cruciate ligament is associated with activities that incorporate both abrupt deceleration and catching a ball. In the present study, we examined whether the upper-limb motion involved in catching a ball affected the synchrony of the lower-limb muscles during tasks known to stress the anterior cruciate ligament-namely, abrupt decelerative landings. Seven male and eleven female subjects decelerated abruptly to land in single-limb stance after catching a chest-height pass and after no catching. Ground-reaction force and electromyographic data for six lower-limb muscles were sampled while the subjects' landing technique was filmed. The joint-reaction forces and the sagittal planar net moments for the knee then were calculated to derive the tibiofemoral shear forces. The muscle onsets and peak muscle activities were temporally analyzed with respect to the time of initial foot-ground contact, the peak resultant ground-reaction force, and the peak tibiofemoral shear force. When catching a pass, the subjects demonstrated significantly (p < 0.05) earlier rectus femoris onset relative to the timing of the initial foot-ground contact and of the peak tibiofemoral shear force, and they showed delayed biceps femoris onset relative to the timing of the peak tibiofemoral shear force compared with the findings in the trials without catching. We concluded that catching a ball during an abrupt landing could increase the potential for an anterior cruciate ligament injury by limiting the time available for the hamstring muscles to generate posterior tibial-drawer force before the onset of the quadriceps-induced anterior tibial translation. Clinical Relevance: The integrity of the anterior cruciate ligament during landing relies on the proper coordination of the lower-limb muscles, particularly the quadriceps and the hamstrings. The present study demonstrated that motion of the upper-limbs may interfere with recruitment of these muscles, thereby predisposing the anterior cruciate ligament to injury.
Article
Purpose: Lateral extra-articular tenodesis (LET) may confer improved rotational stability after anterior cruciate ligament reconstruction (ACLR). Little is known about how LET affects in vivo cartilage contact after ACLR. The aim of this study was to investigate the effect of LET in combination with ACLR (ACLR + LET) on in vivo cartilage contact kinematics compared to isolated ACLR (ACLR) during downhill running. It was hypothesised that cartilage contact area in the lateral compartment would be larger in ACLR + LET compared with ACLR, and that the anterior-posterior (A-P) position of the contact center on the lateral tibia would be more anterior after ACLR + LET than after ACLR. Methods: Twenty patients were randomly assigned into ACLR + LET or ACLR during surgery (ClinicalTrials.gov:NCT02913404). At 6 months and 12 months after surgery, participants were imaged during downhill running using biplane radiography. Tibiofemoral motion was tracked using a validated registration process. Patient-specific cartilage models, obtained from 3 T MRI, were registered to track bone models and used to calculate the dynamic cartilage contact area and center of cartilage contact in both the medial and lateral tibiofemoral compartments, respectively. The side-to-side differences (SSD) were compared between groups using a Mann-Whitney U test. Results: At 6 months after surgery, the SSD in A-P cartilage contact center in ACLR + LET (3.9 ± 2.6 mm, 4.4 ± 3.1 mm) was larger than in ACLR (1.2 ± 1.6 mm, 1.5 ± 2.0 mm) at 10% and 20% of the gait cycle, respectively (p < 0.01, p < 0.05). There was no difference in the SSD in cartilage contact center at 12 months after surgery. There was no difference in SSD of cartilage contact area in the medial and lateral compartments at both 6 and 12 months after surgery. There were no adverse events during the trial. Conclusion: LET in combination with ACLR may affect the cartilage contact center during downhill running in the early post-operation phase, but this effect is lost in the longer term. This suggests that healing and neuromuscular adaptation occur over time and may also indicate a dampening of the effect of LET over time. (337 /350 words) LEVEL OF EVIDENCE: Level II.
Article
When pain and effusion have been minimized and patients assume appropriate knee posture at rest and during exercise, the extent of postinjury or postoperative quadriceps femoris neuromuscular inhibition and avoidance during locomotion is reduced. Restoring normal lower-extremity ROM and musculotendinous extensibility (with consideration for biarticular muscles) is foundational to the implementation of an exercise program that integrates the trunk, hip, and ankle muscles into dynamic knee-stabilization challenges while addressing isolated quadriceps femoris deficiencies. Cardiovascular conditioning should be addressed as early as feasible. Although programs generally address anaerobic and aerobic energy systems, increasing patients' fatigue resistance, as evidenced by prolonged maintenance of appropriate functional exercise techniques and body control without verbalized discomfort or observed movement-avoidance patterns, ensures therapists that neuromuscular responsiveness for dynamic knee stabilization is improving.
Article
It was the purpose of the present study to examine the possibility of increased muscle coordination after anterior cruciate ligament (ACL) reconstruction through the wearing of a compression sleeve. Thirty-six patients were studied who had undergone unilateral ACL reconstruction at least 12 months previously. All subjects were required to perform a 10-cm standing drop jump from an elevated platform onto a force plate, to land on one leg, and thereafter maintain a one-legged balance for 25 s. This task was repeated three times without and three times with an elastic compression sleeve worn on the reconstructed limb. For analysis, the task was partitioned into a landing phase (150 ms), an adjusting phase (10s), and a balancing phase (10s). The peak impact loadings were measured in each direction (Fx, Fy, and Fz) during landing, while force-time integrals (intFz, intFy, and intFz) and root mean square (RMS) error of these forces were calculated for the adjusting and balancing phases. The path length and RMS of the center of pressure coordinates (Ax and Ay) were obtained for the adjusting and balancing phases combined. Drop landings with the bandage produced significantly larger (P < 0.001) peak ground reaction forces in the vertical and anteroposterior direction, suggesting increased subject confidence in their knee. Wearing the knee bandage also enabled the patients to reduce all measured parameters in the anteroposterior direction (rmsFx, intFx, rmsAx) during both the adjusting and balancing phases (P < 0.001 ). A significant reduction in the center of pressure path length further indicated an enhanced steadiness during the one-legged stance. It was concluded that a compression sleeve improved the total integration of the balance control system and muscle coordination.
Article
Full-text available
Estimates of knee joint loadings were calculated for 12 normal subjects from kinematic and kinetic measures obtained during both level and downhill walking. The maximum tibiofemoral compressive force reached an average load of 3.9 times body-weight (BW) for level walking and 8 times BW for downhill walking, in each instance during the early stance phase. Muscle forces contributed 80% of the maximum bone-on-bone force during downhill walking and 70% during level walking whereas the ground reaction forces contributed only 20% and 30% respectively. Most total knee designs provide a tibiofemoral contact area of 100 to 300 mm2. The yield point of these polyethylene inlays will therefore be exceeded with each step during downhill walking. Future evaluation of total knee designs should be based on a tibiofemoral joint load of 3.5 times BW at 20 degrees knee flexion, 8 times BW at 40 degrees and 6 times BW at 60 degrees.
Article
The goal of this study was to test the mechanical strength of 4 different cross pins currently available for femoral fixation by loading each cross pin to failure as received and determine the effect of 1 million cycles of fatigue loading. Additionally, the strength of resorbable pins was tested after prolonged exposure to biologic conditions. Six implants each of the Arthrotek LactoSorb (Biomet, Warsaw, Indiana), Mitek RigidFix (DePuy Mitek Inc, Raynham, Massachusetts), Arthrotek Bone Mulch Screw (Biomet), cortical allograft, and control were tested for 3-point failure without prior loading and after cyclic loading between 50 to 200 N at 10 Hz for 1 million cycles. The bioabsorbable pins were placed in sterile water at 37°C and tested after 2, 4, and 6 months for 3-point failure strength. All implants tested without antecedent loading demonstrated adequate strength for initial fixation for hamstring grafts. During fatigue testing, RigidFix implants (n=6) failed at 18,893±8365 cycles (with a central deformation of 0.48±0.11 mm prior to fracture). All of the other implants tested endured 1 million cycles of loading (50-200 N) without fracture or 1.5 mm central deformation. Neither of the bioabsorbable pins demonstrated a significant change in yield strength after prolonged exposure to water. All implants tested demonstrated adequate strength for initial fixation of hamstring grafts. The metal and bone implants far exceed the strength required to sustain mechanical fixation until biological fixation occurs; both polymeric implants demonstrated that they maintained enough mechanical strength to achieve this goal.
Article
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Although extensive research has been conducted on rotational kinematics, the internal/external rotation of the tibio-femoral joint is perhaps less important for protecting joint health than its effect on joint contact mechanics. The purpose of this study was to evaluate tibio-femoral joint contact paths during a functional activity (running) and investigate the relationship between these arthrokinematic measures and traditional kinematics (internal/external rotation). Tibio-femoral motion was assessed for the contralateral (uninjured) knees of 29 ACL-reconstructed individuals during downhill running, using dynamic stereo X-ray combined with three-dimensional CT bone models to produce knee kinematics and dynamic joint contact paths. The joint contact sliding length was estimated by comparing femoral and tibial contact paths. The difference in sliding length between compartments was compared to knee rotation. Sliding length was significantly larger on the medial side (10.2 ± 3.8 mm) than the lateral side (2.3 ± 4.0 mm). The difference in sliding length between compartments (mean 7.8 ± 3.0 mm) was significantly correlated with internal tibial rotation (P < 0.01, R (2) = 0.74). The relationship between rotational knee kinematics and joint contact paths was specifically revealed as greater tibial internal rotation was associated with larger magnitude of sliding motion in the medial compartment. This could suggest that lateral pivot movement occurs during running. Rotational kinematics abnormality should be treated for restoring normal balance of joint sliding between medial and lateral compartments and preventing future osteoarthritis. Prognostic studies, Level II.
Article
Osteoarthritis is the most common joint disorder with aging, but its cause is unknown. Mice lose joint afferents with aging, and this loss precedes development of osteoarthritis. We hypothesized a loss of joint afferents is involved in the pathogenesis of osteoarthritis. To test this hypothesis, we denervated knee joints of 16 rats at age 2 months, by intra-articular injection of an immunotoxin. The immunotoxin killed neurons after retrograde axonal transport to the cell body. At 16 or 24 months follow-up, each joint was histologically assessed and assigned an osteoarthritis score. At follow-up, the number of joint afferents had spontaneously decreased by 42% in control knees and 69% in denervated knees. We found that control knees developed osteoarthritic changes with aging. However, denervated knees had far more severe changes, as evidenced by a 54% higher average osteoarthritis score than control knees (P = 0.0016, both groups 16 knees). These results suggest a loss of afferents predisposes a joint to osteoarthritis. We propose the spontaneous loss of neurons with aging may be a normal developmental process. To explain the mechanism causing osteoarthritis, we suggest denervation permits aberrant joint loading, either by disturbing neuromuscular joint control, or by inducing joint laxity after neurogenic loss of tissue homeostasis.
Article
Purpose: To determine the in?vivo dynamic graft bending angle (GBA) in anterior cruciate ligament (ACL)-reconstructed knees, correlate the angle to tunnel positions and tunnel widening, and evaluate the effects of 2 femoral tunnel drilling techniques on GBA. Methods: Patients with an isolated ACL injury undergoing reconstruction from 2011 to 2012 were included. Transportal techniques were used to create femoral tunnels. Tunnel locations were determined by 3-dimensional computed tomography. Tibiofemoral kinematics during treadmill walking and running were assessed by dynamic stereo x-ray analysis 6?months and 2?years postoperatively. The GBA was calculated from the 3-dimensional angle between the graft and femoral tunnel vectors on each motion frame. The cross-sectional areas of femoral tunnels were measured at 6?months and compared with the initial size to assess tunnel widening. Results: A total of 54 patients were included. Use of flexible drills resulted in significantly higher GBAs during walking (80.6? ? 7.8?, P < .001) and running (80.5? ? 9.0?, P?= .025) than rigid drills (walking, 67.5? ? 9.3?; running, 74.1? ? 9.6?). Their use led to greater tunnel widening of 113.9% ? 17.6%, as compared with 97.7% ? 17.5% for rigid drills (P?= .003). The femoral and tibial apertures were located in similar anatomic positions in both groups, but the femoral tunnel exits were located more anteriorly (P < .001) in the flexible drill group. A higher GBA was highly correlated with anterior location of femoral exits (r?= 0.63, P < .001) and moderately correlated with greater tunnel widening (r?= 0.48, P < .001). Conclusions: High GBAs were identified during dynamic activities after anatomic ACL reconstruction with a transportal femoral tunnel drilling technique. The GBA was greater when flexible drills were used. The high bending angle resulted from the more anterior location of the femoral tunnel exits, and it correlated with early bone tunnel widening at 6?months. These results suggest that a high GBA may increase stress at the bone-graft interface and contribute to greater tunnel widening after anatomic ACL reconstruction, although the clinical impact should be further investigated. Level of evidence: Level III, retrospective comparative study.
Chapter
The unique structure of articular cartilage provides the intrinsic functional properties that enable the knee joint to withstand and resist excessive compressive and biomechanical loads, facilitating almost frictionless knee movement. This chapter outlines the architectural and compositional features of articular cartilage. The relationships of chondrocytes to their pericellular environment, the territorial and interterritorial matrix domains as well as the zonal heterogeneity and compartmentalization from the articular surface to the subchondral bone are highlighted. Coupled with the biomechanical functions of articular cartilage, the lubrication mechanisms of knee articular cartilage along with the molecular structure, composition and concentration of the constituent lubricants critical in facilitating a smooth gliding movement of the opposing articular cartilage are discussed.
Chapter
The aim of this paper is to provide sound principles of electromyography (EMG) signal acquisition and processing in order to optimize signal quality and therefore lead to better interpretation of mechanical muscle output during sport medicine applications and rehabilitation. Some background information is provided on the source of the EMG signal, factors affecting its quality, recording techniques, signal processing, fidelity and reproducibility of the signal, and some applications in sport medicine and rehabilitation. The descriptions of EMG research applications in rehabilitation are not an exhaustive review of all major areas but only a few examples in the areas of signal reliability, muscle activation and timing, and muscle fatigue.
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The knee joint has biomechanical roles in allowing gait, flexing and rotating yet remaining stable during the activities of daily life, and transmitting forces across it. Geometrical, anatomical and structural considerations allow the knee joint to accomplish these biomechanical roles. These are addressed and discussed in this article.
Article
This investigation sought to identify neuromechanical mechanisms by which a subject with an anterior cruciate ligament (ACL)-deficient knee might cope with the potentially destabilizing joint stresses during both level and downhill walking. Kinematic, kinetic and electromyographic data were collected from 21 subjects with arthroscopically verified ACL-deficient knees and Lysholm scores of 55–100 ( ), as well as from 12 healthy control subjects. Electromyographic data were recorded from the skin surface overlying rectus femoris, biceps femoris and gastrocnemius muscles. A dismountable slope of 6 m length and a gradient of 19% was constructed for downhill walking. Sagittal plane net joint moments and muscle mechanical power at the knee joint were calculated from force platform and videographic records using the inverse dynamics approach. During level walking there were no kinematic nor kinetic differences seen between ACL-deficient subjects and normals. The typical profile of muscle power at the knee contained three peaks during stance: an eccentric peak during early stance (K1); a concentric peak at mid stance (K2); and a second smaller eccentric peak (K3) during late stance. During downhill walking ACL-deficient subjects displayed a significantly smaller K1 compared to normals and their K1:K3 ratio was significantly less than that of normal subjects. Whereas normal subjects showed no hamstring activity during stance in level walking there was continuous activity throughout the stance phase displayed by the ACL-deficient and normal subjects. During downhill walking both the ACL-deficient and normal subjects showed continuous hamstring activity. However, the ACL-deficient subjects showed a significant delay in peak hamstring activity during late swing. Both groups on average displayed gastrocnemius peak activity just on heel strike during downhill walking but the linear envelopes of the ACL-deficient subjects were much more tightly time-locked to this critical event.
Article
This article provides an overview of the clinical management of common complications following knee osteotomy procedures with or without concurrent anterior cruciate ligament reconstruction.
Article
Purpose: To evaluate the effect of knee hyperextension on dynamic in vivo kinematics after anterior cruciate ligament reconstruction (ACL-R). Methods: Forty-two patients underwent unilateral ACL-R. Twenty-four months after surgery, subjects performed level walking and downhill running on a treadmill while dynamic stereo radiographs were acquired at 100 (walking) and 150 Hz (running). Tibiofemoral motion was determined using a validated model-based tracking process, and tibiofemoral translations/rotations were calculated. The range of tibiofemoral motions from 0 to 10% of the gait cycle (heel strike to early stance phase) and side-to-side difference (SSD) were calculated. Maximum knee extension angle of ACL-reconstructed knees during walking was defined as active knee extension angle in each subject. Correlations between maximum knee extension angle and tibiofemoral kinematics data were evaluated using Spearman's rho (P < 0.05). Results: No significant correlation was observed between maximum knee extension angle and the range of anterior tibial translation during functional activities in the ACL-R knees. Maximum knee extension angle was weakly correlated with internal tibial rotation range in ACL-R knee during running (ρ = 0.376, P = 0.014); however, maximum extension angle was not correlated with SSD of internal tibial rotation. SSD of internal tibial rotation was -0.4° ± 1.9° (walking), -1.6° ± 3.1° (running), indicating ACL-R restored rotatory knee range of motion during functional movements. Conclusion: Knee hyperextension was not significantly correlated with greater SSD of anterior translation and internal rotation. The clinical relevance is that knee hyperextension does not adversely affect kinematic outcomes after ACL-R and that physiologic knee hyperextension can be restored after ACL-R when knee hyperextension is present. Level of evidence: III.
Article
In an investigation of segmental control of the upper body during the execution of a ramped descent followed by a cutting maneuver, we observed that individuals with a unilateral anterior cruciate ligament deficiency (ACLD) modified the timing of head and trunk segment control in comparison to a non-injured control group (Reed-Jones and Vallis, 2007). Head and trunk coordination during redirection tasks is controlled via a specific motor control pattern, where the head leads whole body redirection. This specific motor control sequence has been proposed as a central feed-forward process that facilitates optimal gathering of sensory information for the dynamic updating of spatial orientation representations (Grasso et al. 1996, 1998; Patla et al. 1999; Hollands et al. 2001; Vallis and Patla 2004). Modification of this specific sequence points to an adaptive process in the central nervous system to compensate for ACL loss. The findings from our study provide significant additions to the current state of knowledge regarding proprioceptive loss as it demonstrates that adaptive changes following ACL injury are not limited to lower limb control, as has been the focus of published research to date. Rather, ACLD appears to influence motor coordination on a global level, including head and trunk movement strategies. In light of these new insights in the modification of control processes during complex locomotor tasks, there is clearly a need for the inclusion of more global, whole body control strategies in both scientific research and rehabilitative approaches when working with individuals following an ACL loss. ACLD may not simply be a musculoskeletal injury, but in fact, a neurophysiological disorder that results from deafferentation of the knee joint (Kapreli and Athanasopoulos, 2006). The direction of future research in ACLD would benefit from examining whether anterior cruciate ligament deficiency results in significant peripheral proprioceptive deficiency.
Article
Background: A high graft bending angle (GBA) after anterior cruciate ligament (ACL) reconstruction has been suggested to cause stress on the graft. Nevertheless, evidence about its effect on graft healing in vivo is limited. Hypothesis: The signal intensity on magnetic resonance imaging (MRI) would be higher in the proximal region of the ACL graft, and higher signals would be correlated to a higher GBA. Study design: Descriptive laboratory study. Methods: Anatomic single-bundle ACL reconstruction was performed on 24 patients (mean age, 20 ± 4 years) using the transportal technique. A quadriceps tendon autograft with a bone plug was harvested. To evaluate graft healing, the signal/noise quotient (SNQ) was measured in 3 regions of interest (ROIs) of the proximal, midsubstance, and distal ACL graft using high-resolution MRI (0.45 × 0.45 × 0.70 mm), with decreased signals suggesting improved healing. Dynamic knee motion was examined during treadmill walking and running to assess the in vivo GBA. The GBA was calculated from the 3-dimensional angle between the graft and femoral tunnel vectors at each motion frame, based on tibiofemoral kinematics determined from dynamic stereo X-ray analysis. Graft healing and GBAs were assessed at 6 and 24 months postoperatively. Repeated-measures analysis of variance was used to compare the SNQ in the 3 ROIs at 2 time points. Pearson correlations were used to analyze the relationship between the SNQ and mean GBA during 0% to 15% of the gait cycle. Results: The SNQ of the ACL graft in the proximal region was significantly higher than in the midsubstance ( P = .022) and distal regions ( P < .001) at 6 months. The SNQ in the proximal region was highly correlated with the GBA during standing ( R = 0.64, P < .001), walking ( R = 0.65, P = .002), and running ( R = 0.54, P = .015) but not in the other regions. At 24 months, signals in the proximal and midsubstance regions decreased significantly compared with 6 months ( P < .001 and P = .008, respectively), with no difference across the graft area. Conclusion: The signal intensity was highest in the proximal region and lowest in the distal region of the reconstructed graft at 6 months postoperatively. A steep GBA was significantly correlated with high signal intensities of the proximal graft in this early period. A steep GBA may negatively affect proximal graft healing after ACL reconstruction.
Article
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The reason for the higher incidence of anterior cruciate ligament injury from non-contact mechanisms in female athletes is not known. Stability of the joint from dynamic restraints occurs through proprioceptive and kinaesthetic mechanisms providing a flexion moment. Reflexive muscle activation is different between the sexes, but it is unclear if sex differences exist in the ability to dynamically stabilise joints through a neuromuscular feed forward process as measured by preactivation of the muscles. To determine if the level of preactivation of the gastrocnemius and hamstring muscles during dynamic activity is affected by sex. Thirty four healthy active subjects, evenly grouped by sex, participated in the study. Maximum voluntary contraction normalised electromyographic (EMG) activity of the quadriceps, hamstrings, and gastrocnemius muscles was recorded during downhill walking (0.92 m/s) and running (2.08 m/s) on a 15 degrees declined treadmill. Preactivation of the EMG signal was calculated by setting a mark 150 milliseconds before foot strike, as indicated by a footswitch. Multiple t tests for sex differences of preactivity mean percentage (M-EMG%) during the downhill activities were performed. The female subjects had a higher M-EMG% for the medial hamstrings than the male subjects (31.73 (9.89) and 23.04 (8.59) respectively; t((2,32)) = 2.732, p = 0.01) during walking. No other muscles exhibited a sex difference in M-EMG% during either activity. The female subjects in this study showed higher medial hamstring preactivation. However, this may be because they were not injured, indicating their propensity for joint stabilisation. A long term prospective study is required to eliminate this potential explanation. No sex difference in gastrocnemius preactivation was seen, adding to the controversy about whether this muscle contributes to feed forward joint stability. Further research of preactivation of the musculature of the leg is required.
Article
Mechanical properties of the stress-shielded patellar tendon were studied in the rabbit knee. Stress shielding was accomplished by stretching a stainless-steel wire installed between the patella and tibial tubercle and thus, releasing the tension in the patellar tendon completely. Tensile tests were carried out on the specimens obtained from the patellar tendons which were exposed to the stress shielding for 1 to 6 weeks. The stress shielding changed the mechanical properties of the patellar tendon significantly: it decreased the tangent modulus and tensile strength to 9 percent of the control values after 3 weeks. There was a 131 percent increase in the cross-sectional area and a 15 percent decrease in the tendinous length. Remarkable changes were also observed in the structural properties: for example, the maximum load of the bone-tendon complex decreased to 20 percent of the control value after 3 weeks. Histological studies showed that the stress shielding increased the number of fibroblasts and decreased the longitudinally aligned collagen bundles. These results imply that if no stress is applied to the autograft in the case of augmentative reconstruction of the knee ligament, the graft strength decreases remarkably.
Article
The load moment of force about the knee joint during machine milking and when lifting a 12.8 kg box was quantified using a computerized static sagittal plane body model. Surface electromyography of quadriceps and hamstrings muscles was normalized and expressed as a percentage of an isometric maximum voluntary test contraction. Working with straight knees and the trunk flexed forwards induced extending knee load moments of maximum 55 Nm. Lifting the box with flexed knees gave flexing moments of 50 Nm at the beginning of the lift, irrespective of whether the burden was between or in front of the feet. During machine milking, a level difference between operator and cow of 0.70 m − 1.0 m significantly lowered the knee extending moments.To quantify the force magnitudes acting in the tibio-femoral and patello-femoral joints, a local biomechanical model of the knee was developed using a combination of cadaver knee dissections and lateral knee radiographs of healthy subjects. The moment arm of the knee extensor w...
Article
To overcome many of the complications after ACL reconstruction (prolonged knee stiffness, limitation of complete extension, delay in strength recovery, anterior knee pain), yet still maintain knee stability, we developed a rehabilitation protocol that emphasizes full knee extension on the first postoperative day and immediate weightbearing according to the patient's tolerance. Of 800 patients who underwent intraarticular ACL patellar tendon-bone graft reconstruction, performed by the same surgeon, the last 450 patients have followed the accelerated rehabilitation schedule as outlined in the protocol. A longer than 2 year followup is recorded for 73 of the patients in the accelerated rehabilitation group. On the 1st postoperative day, we encouraged these patients to walk with full weightbearing and full knee extension. By the 2nd postoperative week, the patients with a 100° range of motion participated in a guided exercise and strengthening program. By the 4th week, patients were permitted unlimited activities of daily living and were allowed to return to light sports activities as early as the 8th week if the Cybex strength scores of the involved extremity exceeded 70% of the scores of the noninvolved extremity and the patient had completed a sport-specific functional/agility program. The patient database was compiled from frequent clinical examinations, periodic knee questionnaires, and objective information, such as range of motion measurements, KT-1000 values, and Cybex strength scores. A series of graft biopsies obtained at various times have revealed no adverse histologic reaction. The evidence indicates that in this population, the accelerated rehabilitation program has been more effective than our initial program in reducing limitations of motion (particularly knee extension) and loss of strength while maintaining stability and preventing anterior knee pain.
Article
Twenty-eight male and twenty-one female subjects with no history of previous injury to their knees were examined using a newly developed clinical testing apparatus designed to record anterior-posterior tibial force versus displacement and varus-valgus moment versus angulation during manual manipulation of the knee. Joint stiffness and laxity were measured from test tracings made with the knee muscles relaxed and tensed. Agreement between these measurements and those made previously on thirty-five fresh cadaver knee specimens was very good. Anterior-posterior laxity averaged 3.7 millimeters in full extension, 5.5 in 20 degrees of flexion, and 4.8 millimeters in 90 degrees of flexion, while the mean varus-valgus laxity was 6.7 degrees in full extension. The common clinical assumption that normal right-left differences are negligible was found to be invalid. Individual right-left differences averaged 26 to 35 per cent for laxity and 19 to 24 per cent for stiffness. There was no discernible tendency for one knee to be more stable than the other; random interchanges of relative stability between the right and left knees were observed for each individual at different knee positions. When requested to tense the knee muscles, these subjects were able to increase their knee stiffness an average of two to four times while knee laxity was reduced to 25 to 50 per cent of the normal value.
Article
Knee specimens were placed in an apparatus which imposed cyclic anterior-posterior or rotatory forces, with various compressive loads applied to the joint. Force-displacement graphs or torque-rotation graphs were automatically plotted, giving the laxity under various conditions. The ligaments, capsule, and menisci provided joint stability under no-load conditions. However, under compressive loads, the conformity of the condylar surfaces was an important factor in stabilizing the knee. The mechanism proposed was the uphill movement of the femur as the femur and the tibia were displaced or twisted relative to one another.
Article
The mechanical properties of anterior cruciate bone-ligament-bone specimens from humans and rhesus monkeys were determined in tension to failure under high strain-rate conditions. The age range of the human specimens was from sixteen to eighty-six years. The values fro human specimens obtained from young adults with regard to elastic modulus, ultimate tensile stress, and strain energy to failure were approximately two to three times those for specimens from humans in the sixth decade and older. The major mode of failure was ligament disruption in the specimens from young adult humans and avulsion of bone beneath the ligament insertion site in the specimens from older humans. The difference in mode of failure correlated with histological observations of decreased bone mass at the site of ligament attachment in the specimens from older humans. Rhesus monkey specimens had higher values for elastic modulus, failure stress, and strain energy. Significant reductions in strength and stiffness properties of ligament units were shown to occur with advancing age to a greater degree than expected. All experiments in which specimens from older human cadavera are used should be interpreted with caution when the results are applied to mechanisms of ligament failure for younger or athletic individuals.
Article
A long-term retrospective study (minimum 5 years) was done looking at three groups of anterior cruciate deficient knee patients using both subjective and objective anterior cruciate tests. Twenty-seven chronic anterior cruciate ligament deficient knees reconstructed with the middle third of the patellar tendon and 28 chronic anterior cruciate ligament deficient knees reconstructed with the semitendinosus tendon were included in this consecutive group of patients and were felt to be directly comparable. It was found that the chronic anterior cruciate ligament deficient group reconstructed with the semitendinosus tendon had 4 excellent, 10 good, 7 poor, and 7 failures with an objective score averaging 4.5 of a possible 12, while the comparable group reconstructed with the middle third of the patellar tendon had 16 excellent, 7 good, 3 poor, and only 1 failure with a score of 10 of a possible 12 (P less than 0.0032). For completeness sake, 20 anterior cruciate deficient knees from this group of consecutive patients that were reconstructed acutely with the semitendinosus tendon were also examined. This group had 8 excellent results, 9 good, 3 poor, and no failures with a score of 9.8 (P less than 0.03 compared to the other group using the semitendinosus tendon). This comparison between the two groups where the semitendinosus tendon was used in the anterior cruciate ligament reconstruction was made only to show the difference between studies dealing with knee reconstructions. There may be a significant difference between a study dealing with acutely reconstructed knees versus one focusing on chronically reconstructed knees, most likely because of both patient selection and time between injury and reconstruction.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
The structural properties of 27 pairs of human cadaver knees were evaluated. Specimens were equally divided into three groups of nine pairs each based on age: younger (22 to 35 years), middle (40 to 50 years), and older (60 to 97 years). Anterior-posterior displacement tests with the intact knee at 30 degrees and 90 degrees of flexion revealed a significant effect of knee flexion angle, but not of specimen age. Tensile tests of the femur-ACL-tibia complex were performed at 30 degrees of knee flexion with the ACL aligned vertically along the direction of applied tensile load. One knee from each pair was oriented anatomically (anatomical orientation), and the contralateral knee was oriented with the tibia aligned vertically (tibial orientation). Structural properties of the femur-ACL-tibia complex, as represented by the linear stiffness, ultimate load, and energy absorbed, were found to decrease significantly with specimen age and were also found to have higher values in specimens tested in the anatomical orientation. In the younger specimens, linear stiffness (242 +/- 28 N/mm) and ultimate load (2160 +/- 157 N) values found when the femur-ACL-tibia complex was tested in the anatomical orientation were higher than those reported previously in the literature. These values provide new baseline data for the design and selection of grafts for ACL replacement in an attempt to reproduce normal knee kinematics.
Article
Morphologic, physiologic, and clinical evidence for the sensory role of the cruciate ligaments is reviewed. The cruciate ligaments accommodate morphologically different sensory nerve endings (Ruffini endings, Pacinian corpuscles, Golgi tendon organlike endings, and free nerve endings) with different capabilities of providing the central nervous system with information not only about noxious and chemical events but also about characteristics of movements and position-related stretches of these ligaments. A survey of available data reveals that low threshold joint-ligament receptor (i.e., mechanoreceptor) afferents evoke only weak and rare effects in skeletomotor neurons (alpha-motor neurons), while they frequently and powerfully influence fusimotor neurons (gamma-motor neurons). The effects on the gamma-muscle-spindle system in the muscles around the knee are so potent that even stretches of the cruciate ligaments at relatively moderate loads (not noxious) may induce major changes in responses of the muscle spindle afferents. As the activity in the primary muscle spindle afferents modifies the stiffness in the muscles, the cruciate ligament receptors, via the gamma-muscle-spindle system, may participate in the regulation and preprogramming of the muscular stiffness around the knee joint and thereby of the knee joint stiffness. Thus, the sensory system of the cruciate ligaments is able to significantly contribute to the functional stability of the knee joint.
Article
A new technique was used to measure the resultant forces in the anterior cruciate ligament during a series of loading experiments on seventeen fresh-frozen cadaver specimens. The base of the ligament's tibial attachment was mechanically isolated with a coring cutter, and a specially designed load-transducer was fixed to the bone-plug that contained the ligament's tibial insertion so that the resultant forces were directly measured by the load-cell. Although the magnitudes of values for forces varied considerably between specimens for a given test condition, the patterns of loading with respect to direction of loading and the angle of flexion of the knee were remarkably consistent. Passive extension of the knee generated forces in the ligament only during the last 10 degrees of extension; at 5 degrees of hyperextension, the forces ranged from fifty to 240 newtons (mean, 118 newtons). When a 200-newton pull of the quadriceps tendon was applied to extend a knee slowly against tibial resistance, however, the force in the ligament increased at all angles of flexion of the knee. Internal tibial torque always generated greater forces in the ligament than did external tibial torque; higher forces were recorded as the knee was extended. The greatest forces (133 to 370 newtons) were generated when ten newton-meters of internal tibial torque was applied to a hyperextended knee. Fifteen newton-meters of applied varus moment generated forces of ninety-four to 177 newtons at full extension; fifteen newton-meters of applied valgus moment generated a mean force of fifty-six newtons, which remained unchanged with flexion of the knee. The force during straight anterior translation of the tibia was approximately equal to the anterior force applied to the tibia. The application of 925 newtons of tibiofemoral contact force reduced the mean force in the ligament that was generated by 200 newtons of anterior pull on the tibia by 36 per cent at full extension and 46 per cent at 20 degrees of flexion.
Article
The electromyographic activities of six muscles of the thigh were recorded, using bipolar surface electrodes, during active extension of the knee by six healthy men. The signal amplitudes were normalized to those recorded during isometric maximum voluntary contractions. Extension of the knee from 90 to 0 degrees (full extension) was performed at the rate of 10 degrees per second with the leg unimpeded and with weights of 1.8, 3.6, 5.4, or 7.2 kilograms attached to the ankle. The hamstrings were found to coactivate with the quadriceps during the terminal phase of extension. Coactivation of all three hamstrings was found to occur at joint angles of as much as 9 degrees, with the maximum at full extension of the knee and the strength of the signals ranging to as much as 20 per cent. The signals of all of the flexors and extensors increased with increasing loads on the ankle and, with the exception of the rectus femoris at 9 degrees of flexion, they also increased as the knee extended. The results of this study support the hypothesis that the hamstrings function synergistically with the anterior cruciate ligament to prevent the anterior tibial displacement that is produced by active contraction of the quadriceps in the terminal degrees of extension of the knee. This information is important for the physical conditioning of healthy individuals in preparation for athletic endeavors. Furthermore, if coactivation of the hamstrings with the quadriceps is mediated by sensors other than, or in addition to, those of the anterior cruciate ligament, then strengthening of the hamstrings appears to be an important adjunct to rehabilitation programs after repair or reconstruction of that ligament.
Article
Different surgical methods of graft fixation in ACL reconstruction were examined to determine the effects on mechanical properties of the reconstructed ACL. Ten human cadavers were used in this study. Six different types of grafts were studied. The tendon grafts were removed from each cadaver and fixed to femurs and tibias as ACL substitutes with different surgical fixation methods, leaving femur-reconstructed graft-tibia preparations. The surgical techniques used were staple fixation, tying sutures over buttons, and screw fixation. In the latter, the screws were introduced through femoral and tibial drill holes from the outside in order to achieve interference fit as described by Lambert. Tensile testing demonstrated that the original ACL is significantly stronger than the graft used for reconstruction in linear load, stiffness, and maximum tensile strength. All of the failures of the reconstructed ACL grafts occurred at the fixation site, indicating that the mechanically weak link of the reconstructed graft is located at the fixation site. Among the different methods of fixation, one-third of the patellar tendon secured with a cancellous screw, especially with a custom designed large diameter screw, showed significantly higher values. Although many other factors affect the success of ACL reconstruction, our study indicates that the method of surgical fixation is the major factor influencing the graft's mechanical properties in the immediate postoperative period.
Article
The objective of this study was to quantify the coacti vation patterns of the knee flexor and extensor muscles as part of continued efforts to identify the role of the antagonist muscles in maintaining joint stability. The simultaneous EMG from the flexor and extensor muscles of the knee were recorded during maximal effort, slow isokinetic contractions (15 deg/sec) on the plane parallel to the ground to eliminate the effect of gravity. The processed EMG from the antagonist mus cle was normalized with respect to its EMG as agonist at maximal effort for each joint angle. The plots of normalized antagonist EMG versus joint angle for each muscle group were shown to relate inversely to their moment arm variations over the joint range of motion. Additional calculations demonstrated that the antago nist exerts nearly constant opposing torque throughout joint range of motion. Comparison of data recorded from normal healthy subjects with that of high perform ance athletes with hypertrophied quadriceps demon strated strong inhibitory effects on the hamstrings coac tivations. Athletes who routinely exercise their ham strings, however, had a coactivation response similar to that of normal subjects. We concluded that coactivation of the antagonist is necessary to aid the ligaments in maintaining joint stability, equalizing the articular surface pressure dis tribution, and regulating the joint's mechanical imped ance. The reduced coactivation pattern of the unexer cised antagonist to a hypertrophied muscle increases the risk of ligamentous damage, as well as demon strates the adaptive properties of the antagonist muscle in response to exercise. It was also concluded that reduced risk of knee injuries in high performance ath letes with muscular imbalance could result from com plementary resistive exercise of the antagonist muscle.
Article
We have performed an arthroscopic and histological study of the remodelling process of allogeneic tendons transplanted into the human knee as anterior cruciate ligament substitutes. Arthroscopic observations from six weeks to 55 months after operation showed that the grafts were viable, and that early surface hypervascularity subsided with time; moreover, these appearances remained unchanged from 11 months postoperatively onwards. Histological studies from three to 55 months after operation showed that all the grafts were infiltrated with fibroblasts, and that cellularity in their substance reduced with time, remaining unchanged from 18 months onwards; the collagen bundles were aligned as in a normal ligament from six months onwards. These findings suggest that the grafts reach maturity within the first 18 months and remain unchanged as viable ligaments thereafter.
The load moment of force about the knee joint during machine milking and when lifting a 12.8 kg box was quantified using a computerized static sagittal plane body model. Surface electromyography of quadriceps and hamstrings muscles was normalized and expressed as a percentage of an isometric maximum voluntary test contraction. Working with straight knees and the trunk flexed forwards induced extending knee load moments of maximum 55 Nm. Lifting the box with flexed knees gave flexing moments of 50 Nm at the beginning of the lift, irrespective of whether the burden was between or in front of the feet. During machine milking, a level difference between operator and cow of 0.70 m - 1.0 m significantly lowered the knee extending moments. To quantify the force magnitudes acting in the tibio-femoral and patello-femoral joints, a local biomechanical model of the knee was developed using a combination of cadaver knee dissections and lateral knee radiographs of healthy subjects. The moment arm of the knee extensor was significantly shorter for women than for men, which resulted in higher knee joint forces in women if the same moment was produced. A diagram for quantifying patellar forces was worked out. The force magnitudes given by the knee joint biomechanical model correlated well with experimentally forces measured by others. During the parallel squat in powerlifting, the maximum flexing knee load moment was estimated to 335-550 Nm when carrying a 382.5 kg burden and the in vivo force of a complete quadriceps tendon-muscle rupture to between 10,900 and 18,300 N. During isokinetic knee extension, the tibio-femoral compressive force reached peak magnitudes of 9 times body weight and the anteroposterior shear force was close to 1 body weight at knee angles straighter than 60 degrees, indicating that high forces stress the anterior cruciate ligament. A proximal resistance pad position decreased the shear force considerably, and this position is recommended in early rehabilitation after anterior cruciate ligament repairs or reconstructions. The methods presented quantify muscle activity, sagittal knee joint moments and forces, enabling assessments to be made of different work postures, training exercises and joint derangements.
Article
To investigate the phasic activity of the lower extremity muscles during up- and downslope walking, five muscles of ten healthy men were examined by telemetered electromyography (EMG). The muscles were the tibialis anterior (TA), gastrocnemius (Gc), rectus femoris (RF), semitendinosus (St) and gluteus maximus (GM). The inclination of the slope was 3, 6, 9 and 12 degrees. EMG of the muscles and the time factors of a walking cycle were recorded by a 12-channel polygraph simultaneously. In upslope walking, the duration of TA, St and GM activity was longer and that of RF activity was shorter than in level walking. The phasic pattern of Gc in upslope walking was the same as in level walking. In downslope, the duration of Gc and RF activity was longer than on the level. St showed biphasic activities. The phasic pattern of TA and GM was nearly the same as in level walking. The phasic activity of the muscles altered with an inclination over 6 degrees in upslope, and over 3 degrees in downslope. The findings indicate that the muscles stabilize the knee and ankle joint much more in slope walking than in level walking, and in slope walking they also exert themselves to elevate or lower the body weight.
Article
An engineering study of the forces acting at the human knee joint during walking up ramps and stairs, and during level walking using high heeled shoes, has been made. The work has application in studies of the forces acting in the artificial and natural joints of amputees.
Article
An engineering analysis has been developed which enables the forces transmitted by the joints of the lower limb to be calculated from experimental data. This paper describes a further extension of the analysis to investigate the mechanics of muscle action in locomotion. The results describe the relation of muscle tension to length and velocity and the function of muscle in the production and absorption of energy.
Article
Although numerous procedures have been described for the reconstruction of the anterior and posterior cruciate ligaments, there has been little evaluation of the viability and strength of these substitutes. Using microangiographic, histological, and biomechanical techniques, we studied the vascularity and tensile strength of the medial one-third of the patellar tendon at intervals after it had been inserted as a substitute for either the anterior or the posterior cruciate ligament in twenty-nine young adult Rhesus monkeys. For the anterior cruciate reconstruction (nineteen knees), we used and medial one-third of the patellar tendon elongated by a portion of the patella. For the posterior cruciate reconstruction (ten knees), we used the medial one-third of the patellar tendon lengthened by attached portions of the patella and tibia as a free graft. Both the anterior and the posterior cruciate ligament substitutes were revascularized at eight weeks, and at one year they had approximately 80 per cent of the tensile strength that they had prior to transfer.
Musculoskeletal dynamics, locomotion and clinical applications Basic orthopaedic biomechanics
  • Andriacchi Pt
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Andriacchi PT, Mikosz RP (1991) Musculoskeletal dynamics, locomotion and clinical applications. In: Mow VC, Hayes WC (eds) Basic orthopaedic biomechanics. Raven Press, New York, pp 5t-92
The strength of the anterior cruci-ate ligament in humans and rhesus monkeys Age related and species related changes
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Noyes FR, Grood ES (1976) The strength of the anterior cruci-ate ligament in humans and rhesus monkeys. Age related and species related changes. J Bone Joint Surg [Am] 58: 1074-1082
Anterior and posterior cruciate ligament reconstruction in rhesus monkeys
  • W G Clancy
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  • M Wisconsin
  • WG Clancy
Musculoskeletal dynamics, locomotion and clinical applications
  • P T Andriacchi
  • R P Mikosz
  • PT Andriacchi