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Muscle contributions to tibiofemoral shear forces and valgus and rotational joint moments during single leg drop landing

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Anterior cruciate ligament (ACL) injuries commonly occur during single leg landing tasks and are a burdensome condition. Previous studies indicate that muscle forces play an important role in controlling ligamentous loading, yet these studies have typically used cadaveric models considering only the knee‐spanning quadriceps, hamstrings and gastrocnemius muscle groups. Any muscles (including non‐knee‐spanning muscles) capable of opposing the anterior shear joint reaction force and the valgus joint reaction moment are thought to have the greatest potential for protecting the ACL from injury. Thus, the purpose of this study was to investigate how lower‐limb muscles modulate knee joint loading during a single leg drop landing task. An electromyography‐informed neuromusculoskeletal modelling approach was used to compute lower‐limb muscle force contributions to the anterior shear joint reaction force and the valgus joint reaction moment at the knee during a single leg drop landing task. The average shear joint reaction force ranged from 153N of anterior shear force to 744N of posterior shear force. The muscles that generated the greatest posterior shear force were the soleus, medial hamstrings, and biceps femoris, contributing up to 393N, 359N and 162N, respectively. The average frontal plane joint reaction moment ranged from a 19Nm varus moment to a 6Nm valgus moment. The valgus moment was primarily opposed by the gluteus medius, gluteus minimus and soleus, with these muscles providing contributions of up to 38Nm, 22Nm and 20Nm towards a varus moment, respectively. The findings identify key muscles that mitigate loads on the ACL.
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1664
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Scand J Med Sci Sports. 2020;30:1664–1674.
wileyonlinelibrary.com/journal/sms
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INTRODUCTION
Athletes that participate in sports requiring high-impact land-
ings and cutting tasks are at risk of anterior cruciate ligament
(ACL) injury.1 The majority of these injuries are treated with
surgical intervention1 resulting in substantial convalescence
and rehabilitation time2 as well as associated financial costs.3
Moreover, ACL rupture is associated with potential long-term
consequences, including high re-injury rates (~15%)4 and the
development of knee osteoarthritis later in life.5 Therefore,
prevention of ACL injury is pertinent, and knowledge regard-
ing the mechanical factors related to ACL injury and injury
risk is needed to develop effective prophylactic strategies.
Anterior cruciate ligament rupture occurs when the me-
chanical load experienced by the ligament exceeds the liga-
ment's ability to withstand that mechanical load. Rupture may
Received: 1 December 2019
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Revised: 14 April 2020
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Accepted: 7 May 2020
DOI: 10.1111/sms.13711
ORIGINAL ARTICLE
Muscle contributions to tibiofemoral shear forces and valgus and
rotational joint moments during single leg drop landing
NiravManiar1
|
Anthony G.Schache2
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ClaudioPizzolato3,4
|
David A.Opar1
© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
1School of Behavioural and Health,
Australian Catholic University, Melbourne,
Vic, Australia
2La Trobe Sports and Exercise Medicine
Research Centre, La Trobe University,
Melbourne, Vic, Australia
3School of Allied Health Sciences, Griffith
University, Gold Coast, QLD, Australia
4Griffith Centre of Biomedical and
Rehabilitation Engineering (GCORE),
Menzies Health Institute Queensland,
Griffith University, Gold Coast, QLD,
Australia
Correspondence
Nirav Maniar, School of Behavioural and
Health, Australian Catholic University,
Melbourne, Australia.
Email: Nirav.Maniar@acu.edu.au
Anterior cruciate ligament (ACL) injuries commonly occur during single-leg landing
tasks and are a burdensome condition. Previous studies indicate that muscle forces
play an important role in controlling ligamentous loading, yet these studies have
typically used cadaveric models considering only the knee-spanning quadriceps,
hamstrings, and gastrocnemius muscle groups. Any muscles (including non-knee-
spanning muscles) capable of opposing the anterior shear joint reaction force and the
valgus joint reaction moment are thought to have the greatest potential for protecting
the ACL from injury. Thus, the purpose of this study was to investigate how lower-
limb muscles modulate knee joint loading during a single-leg drop landing task. An
electromyography-informed neuromusculoskeletal modeling approach was used to
compute lower-limb muscle force contributions to the anterior shear joint reaction
force and the valgus joint reaction moment at the knee during a single-leg drop land-
ing task. The average shear joint reaction force ranged from 153 N of anterior shear
force to 744 N of posterior shear force. The muscles that generated the greatest poste-
rior shear force were the soleus, medial hamstrings, and biceps femoris, contributing
up to 393N, 359N, and 162N, respectively. The average frontal plane joint reaction
moment ranged from a 19Nm varus moment to a 6Nm valgus moment. The valgus
moment was primarily opposed by the gluteus medius, gluteus minimus, and soleus,
with these muscles providing contributions of up to 38, 22, and 20Nm toward a varus
moment, respectively. The findings identify key muscles that mitigate loads on the
ACL.
KEYWORDS
anterior cruciate ligament, dynamic coupling, dynamic valgus, neuromechanics, opensim
... Valgus-varus and internal-external rotation typically display small excursions of up to 5° and 20°, respectively [22]. In the sagittal plane, knee flexion angles typically range from 0° (full extension) to 90° for the weightbearing leg in most locomotive tasks [22][23][24][25][26][27], although excursions exceeding this do also occur in commonly performed tasks such as the swing phase of stair ambulation [27] and high-speed running [28]. Although the primary role of the ACL is to resist anterior tibial translation [29], prior investigations of ACL injury and loading mechanisms (see Sect. ...
... In silico approaches use computer simulation techniques that often rely on data collection (e.g., via motion capture data) from healthy organisms. In the context of muscle forces and ACL loading, this involves employing musculoskeletal modelling [26,[67][68][69][70][71][72][73][74][75][76][77][78][79] and/or finite element modelling [71,[80][81][82][83][84] techniques. The use of these techniques offers several distinct advantages. ...
... Additionally, musculoskeletal modelling can overcome some limitations of cadaveric approaches, whereby interactions between muscle forces and whole-body skeletal dynamics can be accounted for [64]. As such, the contribution of both kneespanning and non-knee-spanning muscles to knee joint loading can be assessed by determining muscular contributions to ground reaction forces (GRF) [26,73,75,86], thereby accounting for dynamic coupling. However, validation of these musculoskeletal simulations poses a fundamental challenge for the research community, as this method is generally based on numerous assumptions and uncertainties [87]. ...
Article
Full-text available
Anterior cruciate ligament (ACL) injuries are one of the most common knee pathologies sustained during athletic participation and are characterised by long convalescence periods and associated financial burden. Muscles have the ability to increase or decrease the mechanical loads on the ACL, and thus are viable targets for preventative interventions. However, the relationship between muscle forces and ACL loading has been investigated by many different studies, often with differing methods and conclusions. Subsequently, this review aimed to summarise the evidence of the relationship between muscle force and ACL loading. A range of studies were found that investigated muscle and ACL loading during controlled knee flexion, as well as a range of weightbearing tasks such as walking, lunging, sidestep cutting, landing and jumping. The quadriceps and the gastrocnemius were found to increase load on the ACL by inducing anterior shear forces at the tibia, particularly when the knee is extended. The hamstrings and soleus appeared to unload the ACL by generating posterior tibial shear force; however, for the hamstrings, this effect was contingent on the knee being flexed greater than ~ 20° to 30°. The gluteus medius was consistently shown to oppose the knee valgus moment (thus unloading the ACL) to a magnitude greater than any other muscle. Very little evidence was found for other muscle groups with respect to their contribution to the loading or unloading of the ACL. It is recommended that interventions aiming to reduce the risk of ACL injury consider specifically targeting the function of the hamstrings, soleus and gluteus medius.
... Performances such as sprint times and jump distances are affected by hamstring function [21,51]. During jump landings and cutting, the anterior shear and rotational forces of the tibia are controlled by hamstring function [35,36]. Excessive strain in the graft is suppressed by the hamstring [35]. ...
... During jump landings and cutting, the anterior shear and rotational forces of the tibia are controlled by hamstring function [35,36]. Excessive strain in the graft is suppressed by the hamstring [35]. For these reasons, knee flexion strength and HQ ratio were significantly higher in the group with better psychological readiness. ...
Article
Full-text available
Abstract Background Information about specific factors of physical function that contribute to psychological readiness is needed to plan rehabilitation for a return to sports. The purpose of this study was to identify specific physical functions related to the psychological readiness of patients aiming to return to sports 6 months after reconstruction. We hypothesized that the knee strength is a factor related to the Anterior Cruciate Ligament–Return to Sport after Injury scale (ACL-RSI) cutoff score for a return to sports. Methods This was a cross-sectional study. Fifty-four patients who had undergone primary reconstruction using hamstring tendon participated in this study. Psychological readiness was measured using the ACL-RSI in patients at 6 months after reconstruction. To identify specific physical functions related to the ACL-RSI score, participants were divided into groups with ACL-RSI scores of ≥ 60 or
... In studies where greater EMG amplitude was found, the hypothesis is related to a compensatory strategy of the central nervous system which increases the muscle recruitment, due to hip posterolateral muscle weakness, a common condition observed in PFP people (Van Cant et al. 2014;Rathleff et al. 2014). Furthermore, a previous study demonstrated that GMed and GMax are two of the key muscles that avoid knee valgus moment during landing (Maniar et al. 2020) and sidestep cutting (Maniar et al. 2018). Therefore, as kinematics responses are task-dependent (Lewis et al. 2015), the role of EMG amplitude of GMed and GMax on PFP people remains controversial and seems to depend on neuromotor strategy adopted and be modulated by muscle weakness. ...
... Previous studies have reported distal mechanical differences in PFP, as an excessive rear foot eversion (Rodrigues et al. 2013), greater tibial internal rotation (Barton et al. 2012) and reduced ankle plantar flexor muscle endurance (Van Cant et al. 2017). However, based on the higher effectiveness of the addition of foot targeted rehabilitation to knee exercises compared to knee targeted exercises alone in individuals with PFP (Molgaard et al. 2018) and the role of soleus in the avoid knee valgus moment (Maniar et al. 2020), future studies need to investigate distal muscle parameters in PFP, since the responses are still completely unknown. ...
Article
We aim to determine the neuromuscular differences in proximal and distal joints between patellofemoral pain (PFP) and healthy participants. Relevant articles were selected through seven databases. Studies comparing electromyography (EMG) or morphology parameters of trunk, hip, ankle/foot joints in PFP people compared to a healthy control group (CG) were included. 1458 studies were identified, from which 36 were included in the systematic review [PFP, n=655; CG, n=649] (31 involving EMG) and 32 in the meta-analysis (27 involving EMG). 75% of studies presented moderate to high methodological quality. The meta-analysis demonstrated that, compared to CG, PFP have: (i) similar transversus abdominis/internal oblique and erector spinae muscle onset, independently of sex; (ii) similar EMG amplitude of gluteus medius and gluteus maximus, independently of sex or task performed; (iii) similar gluteus medius muscle onset, independently of sex or task performed; (iv) similar gluteus maximus muscle onset, independently of sex; (v) a small effect for a shorter activation duration of gluteus medius (0.50; 95% CI [0.07; 0.93]; p=0.02); (vi) a medium effect for a shorter activation duration of gluteus medius during stair/step down task (0.81; 95% CI [0.18; 1.45]; p=0.01); (vii) similar external oblique, gluteus maximus, tensor fascia latae, tibialis anterior and fibularis muscle thickness and (viii) a small effect for a smaller gluteus medius muscle thickness (0.52; 95% CI [0.22; 0.82]; p=0.007). We were not able to perform meta-analysis for EMG at distal joints. Neuromuscular differences in PFP seems to occur only in the gluteus medius muscle. Due to high heterogeneity and several methodological concerns observed, mainly in EMG studies, the interpretation of these results needs caution.
... Performances such as sprint times and jump distances are affected by hamstring function 19,49 . During jump landings and cutting, the anterior shear and rotational forces of the tibia are controlled by hamstring function 33,34 . Excessive strain in the graft is suppressed by the hamstring 33 . ...
... During jump landings and cutting, the anterior shear and rotational forces of the tibia are controlled by hamstring function 33,34 . Excessive strain in the graft is suppressed by the hamstring 33 . For these reasons, knee exion strength and HQ ratio were signi cantly higher in the group with better psychological readiness. ...
Preprint
Full-text available
Background: Information about specific factors of physical function that contribute to psychological readiness is needed to plan rehabilitation for a return to sports. The purpose of this study was to identify specific physical functions related to the psychological readiness of patients aiming to return to sports 6 months after reconstruction. We hypothesized that the knee strength is a factor related to the Anterior Cruciate Ligament–Return to Sport After Injury Scale (ACL-RSI) cutoff score for a return to sports at 2 years after reconstruction. Methods: Fifty-four patients who had undergone primary reconstruction using hamstring tendon participated in this study. Psychological readiness was measured using the ACL-RSI in patients at 6 months after reconstruction. To identify specific physical functions related to the ACL-RSI score, participants were divided into groups with ACL-RSI scores of ³60 or <60. Non-paired t-tests or the Mann-Whitney test were performed to analyze group differences in objective variables in physical function: 1) knee strength in both legs; 2) leg anterior reach distance on both sides; and 3) single-leg hop (SLH) distances in three directions for both legs. Results: Significant differences between groups were identified in knee flexion strength (60°/s) for the uninvolved limb, hamstring-to-quadriceps ratio (60°/s) for the uninvolved limb, knee flexion strength (180°/s) for the involved limb, limb symmetry index (LSI) of leg anterior reach distance, the ratio of the distance to the height of the patient and LSI of SLH distances in lateral and medial directions. Conclusion: This study revealed that at 6 months after reconstruction, increased knee flexion strength (Ratio of the peak torque measured to the body mass of the patient), hamstring-to-quadriceps ratio, leg anterior reach distance LSI, and lateral and medial SLH appear important to exceed the ACL-RSI cutoff for a return to sports at 2 years after reconstruction. The present results may be useful for planning post-operative rehabilitation for long-term return to sports after reconstruction.
... the adductors relative to the abductors may influence lower limb coordination arising from the hip during high-risk maneuvers (e.g., single-leg landings and decelerations) (32). The hip adductor muscles also provide small contributions to knee varus moments early in single-leg landing that may support the ACL against knee valgus moments (33). Further, adductor magnus is a strong hip extensor, particularly when the hip is flexed (34), and weakness of this muscle may limit the ability to absorb energy at the hip, thereby increasing loads applied to the knee (35). ...
Article
Purpose: To determine if a pre-season field-based test battery was prospectively associated with non-contact ACL injury in elite female footballers. Methods: In total, 322 elite senior and junior female Australian Rules Football and soccer players had their isometric hip adductor and abductor strength, eccentric knee flexor strength, countermovement jump (CMJ) kinetics, and single-leg hop kinematics assessed during the 2019 pre-season. Demographic and injury history details were also collected. Footballers were subsequently followed for 18 months for ACL injury. Results: 15 non-contact ACL injuries occurred during the follow-up period. Prior ACL injury (odds ratio [OR] = 9.68, 95% confidence interval [95%CI] = 2.67-31.46), a lower isometric hip adductor to abductor strength ratio (OR = 1.98, 95%CI = 1.09-3.61), greater CMJ peak take-off force (OR = 1.74, 95%CI = 1.09-3.61), and greater single-leg triple vertical hop average dynamic knee valgus (OR = 1.97, 95%CI = 1.06-3.63) and ipsilateral trunk flexion (OR = 1.60, 95%CI = 1.01-2.55) were independently associated with increased risk for subsequent ACL injury. A multivariable prediction model consisting of CMJ peak take-off force, dynamic knee valgus, and ACL injury history that was internally validated classified ACL injured from uninjured footballers with 78% total accuracy. Between-leg asymmetry in lower limb strength and CMJ kinetics were not associated with subsequent ACL injury risk. Conclusions: Pre-season field-based measures of lower limb muscle strength and biomechanics were associated with future non-contact ACL injury in elite female footballers. These risk factors can be used to guide ACL injury screening practices and inform the design of targeted injury prevention training in elite female footballers.
... 57 A neuromuscular modelling approach indicated that during single leg drop landing, the muscles that generated the greatest ACL-protective posterior shear force, were the soleus, medial hamstrings and biceps femoris. 58 In our cohort of ACLR patients although, the contribution of the medial and lateral hamstrings in the involved limb was greater than the uninvolved, but soleus contribution was less than controls bilaterally. In the control group, the ankle appears to contribute 5% more and the hip less during the SLDJ compared with the SLJ. ...
Article
Full-text available
Objectives: Vertical jump performance (height) is a more representative metric for knee function than horizontal hop performance (distance) in healthy individuals. It is not known what the biomechanical status of athletes after anterior cruciate ligament (ACL) reconstruction (ACLR) is at the time they are cleared to return to sport (RTS) or whether vertical performance metrics better evaluate knee function. Methods: Standard marker-based motion capture and electromyography (EMG) were collected from 26 male athletes cleared to RTS after ACLR and 22 control healthy subjects during single leg vertical jumps (SLJ) and single leg drop jumps (SLDJ). Performance outcomes, jump height and the Reactive Strength Index, were calculated. Sagittal plane kinematics, joint moments and joint work were obtained using inverse dynamics and lower limb muscle forces were computed using an EMG-constrained musculoskeletal model. Muscle contribution was calculated as a percentage of the impulse of all muscle forces in the model. Between-limb and between-group differences were explored using mixed models analyses. Results: Jump performance, assessed by jump height and Reactive Strength Index, was significantly lower in the involved than the uninvolved limb and controls, with large effect sizes. For the ACLR group, jump height limb symmetry index was 83% and 77% during the SLJ and SLDJ, respectively. Work generation was significantly less in the involved knee compared to uninvolved limb and controls during the SLJ (p<0.001; d=1.19; p=0.003, d=0.91, respectively) and during the SLDJ (p<0.001; d=1.54; p=0.002, d=1.05, respectively). Hamstrings muscle contribution was greater in the involved compared to the uninvolved limb and controls, whereas soleus contribution was lower in the involved limb compared to controls. Conclusions: During vertical jumps, male athletes after ACLR at RTS still exhibit knee biomechanical deficits, despite symmetry in horizontal functional performance and strength tests. Vertical performance metrics like jump height and RSI can better identify interlimb asymmetries than the more commonly used hop distance and should be included in the testing battery for the RTS.
... As they explain, the positive relationship between gluteal muscle activity and knee FPPA could imply that, when a lack of strength exists, the participant could compensate it by sending more nerve signals to try to activate as much of the gluteal musculature as possible. Moreover, Maniar et al. (Maniar et al., 2020) concluded that the Gmax and Gmed were the main muscles opposing the valgus moment. This statement supports the hypothesis that the participant is trying to send nerve signals to these gluteal muscles to oppose the valgus moment. ...
Article
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Anterior cruciate ligament (ACL) injuries are a burdensome condition due to potential surgical requirements and increased risk of long term debilitation. Previous studies indicate that muscle forces play an important role in the development of ligamentous loading, yet these studies have typically used cadaveric models considering only the knee-spanning quadriceps, hamstrings and gastrocnemius muscle groups. Using a musculoskeletal modelling approach, we investigated how lower-limb muscles produce and oppose key tibiofemoral reaction forces and moments during the weight acceptance phase of unanticipated sidestep cutting. Muscles capable of opposing (or controlling the magnitude of) the anterior shear force and the external valgus moment at the knee are thought to be have the greatest potential for protecting the anterior cruciate ligament from injury. We found the best muscles for generating posterior shear to be the soleus, biceps femoris long head and medial hamstrings, providing up to 173N, 111N and 77N of force directly opposing the anterior shear force. The valgus moment was primarily opposed by the gluteus medius, gluteus maximus and piriformis, with these muscles providing contributions of up to 32 Nm, 19 Nm and 21 Nm towards a knee varus moment, respectively. Our findings highlight key muscle targets for ACL preventative and rehabilitative interventions.
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In this paper we review a series of studies that we initiated to examine mechanisms of ACL injury in the hope that these injuries, and their sequelae, can be better prevented. First, using the earliest in vitro model of a simulated single-leg jump landing or pivot cut with realistic knee loading rates and trans-knee muscle forces, we identified the worst-case dynamic knee loading that causes the greatest peak ACL strain: combined knee compression, flexion and internal tibial rotation. We also identified morphologic factors that help explain individual susceptibility to ACL injury. Second, using the above knee loading, we introduced a possible paradigm shift in ACL research by demonstrating that the human ACL can fail by a sudden rupture in response to repeated sub-maximal knee loading. If that load is repeated often enough over a short time interval, the failure tended to occur proximally, as observed clinically. Third, we emphasize the value of a physical exam of the hip by demonstrating how limited internal axial rotation at the hip both increases the susceptibility to ACL injury in professional athletes, and also increases peak ACL strain during simulated pivot landings, thereby further increasing the risk of ACL fatigue failure. When training at-risk athletes, particularly females with their smaller ACL cross-sections, rationing the number and intensity of worst-case knee loading cycles, such that ligament degradation is within the ACL's ability to remodel, should decrease the risk for ACL rupture due to ligament fatigue failure. This article is protected by copyright. All rights reserved.
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Background: Despite basic characterization of the loading factors that strain the anterior cruciate ligament (ACL), the interrelationship(s) and additive nature of these loads that occur during noncontact ACL injuries remain incompletely characterized. Hypothesis: In the presence of an impulsive axial compression, simulating vertical ground-reaction force during landing (1) both knee abduction and internal tibial rotation moments would result in increased peak ACL strain, and (2) a combined multiplanar loading condition, including both knee abduction and internal tibial rotation moments, would increase the peak ACL strain to levels greater than those under uniplanar loading modes alone. Study design: Controlled laboratory study. Methods: A cadaveric model of landing was used to simulate dynamic landings during a jump in 17 cadaveric lower extremities (age, 45 ± 7 years; 9 female and 8 male). Peak ACL strain was measured in situ and characterized under impulsive axial compression and simulated muscle forces (baseline) followed by addition of anterior tibial shear, knee abduction, and internal tibial rotation loads in both uni- and multiplanar modes, simulating a broad range of landing conditions. The associations between knee rotational kinematics and peak ACL strain levels were further investigated to determine the potential noncontact injury mechanism. Results: Externally applied loads, under both uni- and multiplanar conditions, resulted in consistent increases in peak ACL strain compared with the baseline during simulated landings (by up to 3.5-fold; P ≤ .032). Combined multiplanar loading resulted in the greatest increases in peak ACL strain (P < .001). Degrees of knee abduction rotation (R(2) = 0.45; β = 0.42) and internal tibial rotation (R(2) = 0.32; β = 0.23) were both significantly correlated with peak ACL strain (P < .001). However, changes in knee abduction rotation had a significantly greater effect size on peak ACL strain levels than did internal tibial rotation (by ~2-fold; P < .001). Conclusion: In the presence of impulsive axial compression, the combination of anterior tibial shear force, knee abduction, and internal tibial rotation moments significantly increases ACL strain, which could result in ACL failure. These findings support multiplanar knee valgus collapse as one the primary mechanisms of noncontact ACL injuries during landing. Clinical relevance: Intervention programs that address multiple planes of loading may decrease the risk of ACL injury and the devastating consequences of posttraumatic knee osteoarthritis.
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The tibiofemoral compressive forces experienced during functional activities are believed to be important for maintaining tibiofemoral stability. Previous studies have shown that both knee-spanning and non-knee-spanning muscles contribute to tibiofemoral joint compressive forces during walking. However, healthy individuals typically engage in more vigorous activities (e.g. jumping and cutting) that provide greater challenges to tibiofemoral stability. Despite this, no previous studies have investigated how both knee-spanning and non-knee-spanning muscles contribute to tibiofemoral compressive loading during such tasks. The present study investigated how muscles contributed to the medial and lateral compartment tibiofemoral compressive forces during sidestep cutting. Three-dimensional marker trajectories, ground reaction forces and muscle electromyographic signals were collected from eight healthy males whilst they completed unanticipated sidestep cutting. OpenSim was used to perform musculoskeletal simulations to compute the contribution of each lower-limb muscle to compressive loading of each compartment of the knee. The greatest contributors to medial compartment loading were the vasti, gluteus maximus and medius, and the medial gastrocnemius. The greatest contributors to lateral compartment loading were the vasti, adductors, medial and lateral gastrocnemius, and the soleus. The soleus displayed the greatest potential for unloading the medial compartment, whereas the gluteus maximus and medius displayed the greatest potential for unloading the lateral compartment. These findings may help to inform interventions aiming to modulate compressive loading at the knee.
Article
In-vivo hip joint contact forces (HJCF) can be estimated using computational neuromusculoskeletal (NMS) modelling. However, different neural solutions can result in different HJCF estimations. NMS model predictions are also influenced by the selection of neuromuscular parameters, which are either based on cadaveric data or calibrated to the individual. To date, the best combination of neural solution and parameter calibration to obtain plausible estimations of HJCF have not been identified. The aim of this study was to determine the effect of three electromyography (EMG)-informed neural solution modes (EMG-driven, EMG-hybrid, and EMG-assisted) and static optimisation, each using three different parameter calibrations (uncalibrated, minimise joint moments error, and minimise joint moments error and peak HJCF), on the estimation of HJCF in a healthy population (n = 23) during walking. When compared to existing in-vivo data, the EMG-assisted mode and static optimisation produced the most physiologically plausible HJCF when using a NMS model calibrated to minimise joint moments error and peak HJCF. EMG-assisted mode produced first and second peaks of 3.55 times body weight (BW) and 3.97 BW during walking; static optimisation produced 3.75 BW and 4.19 BW, respectively. However, compared to static optimisation, EMG-assisted mode generated muscle excitations closer to recorded EMG signals (average across hip muscles R2 = 0.60 ± 0.37 versus R2 = 0.12 ± 0.14). Findings suggest that the EMG-assisted mode combined with minimise joint moments error and peak HJCF calibration is preferable for the estimation of HJCF and generation of realistic load distribution across muscles.
Article
Objective: Musculoskeletal models provide a noninvasive means to study human movement and predict the effects of interventions on gait. Our goal was to create an open-source, three-dimensional musculoskeletal model with high-fidelity representations of the lower limb musculature of healthy young individuals that can be used to generate accurate simulations of gait. Methods: Our model includes bony geometry for the full body, 37 degrees of freedom to define joint kinematics, Hill-type models of 80 muscle-tendon units actuating the lower limbs, and 17 ideal torque actuators driving the upper body. The model's musculotendon parameters are derived from previous anatomical measurements of 21 cadaver specimens and magnetic resonance images of 24 young healthy subjects. We tested the model by evaluating its computational time and accuracy of simulations of healthy walking and running. Results: Generating muscle-driven simulations of normal walking and running took approximately 10 minutes on a typical desktop computer. The differences between our muscle-generated and inverse dynamics joint moments were within 3% (RMSE) of the peak inverse dynamics joint moments in both walking and running, and our simulated muscle activity showed qualitative agreement with salient features from experimental electromyography data. Conclusion: These results suggest that our model is suitable for generating muscle-driven simulations of healthy gait. We encourage other researchers to further validate and apply the model to study other motions of the lower-extremity. Significance: The model is implemented in the open source software platform OpenSim. The model and data used to create and test the simulations are freely available at https://simtk.org/home/full_body/, allowing others to reproduce these results and create their own simulations.
Article
Background: Injury to the ipsilateral graft used for reconstruction of the anterior cruciate ligament (ACL) or a new injury to the contralateral ACL are disastrous outcomes after successful ACL reconstruction (ACLR), rehabilitation, and return to activity. Studies reporting ACL reinjury rates in younger active populations are emerging in the literature, but these data have not yet been comprehensively synthesized. Purpose: To provide a current review of the literature to evaluate age and activity level as the primary risk factors in reinjury after ACLR. Study design: Systematic review and meta-analysis. Methods: A systematic review of the literature was conducted via searches in PubMed (1966 to July 2015) and EBSCO host (CINAHL, Medline, SPORTDiscus [1987 to July 2015]). After the search and consultation with experts and rating of study quality, 19 articles met inclusion for review and aggregation. Population demographic data and total reinjury (ipsilateral and contralateral) rate data were recorded from each individual study and combined using random-effects meta-analyses. Separate meta-analyses were conducted for the total population data as well as the following subsets: young age, return to sport, and young age + return to sport. Results: Overall, the total second ACL reinjury rate was 15%, with an ipsilateral reinjury rate of 7% and contralateral injury rate of 8%. The secondary ACL injury rate (ipsilateral + contralateral) for patients younger than 25 years was 21%. The secondary ACL injury rate for athletes who return to a sport was also 20%. Combining these risk factors, athletes younger than 25 years who return to sport have a secondary ACL injury rate of 23%. Conclusion: This systematic review and meta-analysis demonstrates that younger age and a return to high level of activity are salient factors associated with secondary ACL injury. These combined data indicate that nearly 1 in 4 young athletic patients who sustain an ACL injury and return to high-risk sport will go on to sustain another ACL injury at some point in their career, and they will likely sustain it early in the return-to-play period. The high rate of secondary injury in young athletes who return to sport after ACLR equates to a 30 to 40 times greater risk of an ACL injury compared with uninjured adolescents. These data indicate that activity modification, improved rehabilitation and return-to-play guidelines, and the use of integrative neuromuscular training may help athletes more safely reintegrate into sport and reduce second injury in this at-risk population.
Article
The study objective was to investigate the influence of coronal plane alignment and ligament properties on total knee replacement (TKR) contact loads during walking. We created a subject-specific knee model of an 83 year old male who had an instrumented TKR. The knee model was incorporated into a lower extremity musculoskeletal model, and included deformable contact, ligamentous structures and six degree of freedom tibiofemoral and patellofemoral joints. A novel numerical optimization technique was used to simultaneously predict muscle forces, secondary knee kinematics, ligament forces and joint contact pressures from standard gait analysis data collected on the subject. The nominal knee model predictions of medial, lateral and total contact forces during gait agreed well with TKR measures, with RMS errors of 0.23, 0.22, and 0.33 body weight (BW), respectively. Coronal plane component alignment did not affect total knee contact loads, but did alter the medial-lateral load distribution, with 4 deg varus and 4 deg valgus rotations in component alignment inducing +17% and -23% changes in the medial tibiofemoral contact forces at first peak, respectively. A Monte Carlo analysis showed that uncertainties in ligament stiffness and reference strains introduced an approximately ±0.2 BW uncertainty in tibiofemoral force estimates over the gait cycle. Ligament properties had substantial influence on the TKR load distributions, with the medial collateral ligament and iliotibial band properties having the largest effects on medial and lateral compartment loading during stance phase, respectively. The computational framework provides a viable approach for virtually designing TKR components, considering parametric uncertainty and predicting the effects of joint alignment and soft tissue balancing procedures on TKR function during movement.