Zhao D, Banks SA, Mitchell KH, et al. Correlation between the knee adduction torque and medial contact force for a variety of gait patterns

Department of Mechanical & Aerospace Engineering, University of Florida, Gainesville, FL, USA.
Journal of Orthopaedic Research (Impact Factor: 2.99). 06/2007; 25(6):789-97. DOI: 10.1002/jor.20379
Source: PubMed


The external knee adduction torque has been proposed as a surrogate measure for medial compartment load during gait. However, a direct link between these two quantities has not been demonstrated using in vivo measurement of medial compartment load. This study uses in vivo data collected from a single subject with an instrumented knee implant to evaluate this link. The subject performed five different overground gait motions (normal, fast, slow, wide, and toe-out) with simultaneous collection of instrumented implant, video motion, and ground reaction data. For each trial, the knee adduction torque was measured externally while the total axial force applied to the tibial insert was measured internally. Based on data collected from the same subject performing treadmill gait under fluoroscopic motion analysis, a regression equation was developed to calculate medial contact force from the implant load cell measurements. Correlation analyses were performed for the stance phase and entire gait cycle to quantify the relationship between the knee adduction torque and both the medial contact force and the medial to total contact force ratio. When the entire gait cycle was analyzed, R(2) for medial contact force was 0.77 when all gait trials were analyzed together and between 0.69 and 0.93 when each gait trial was analyzed separately (p < 0.001 in all cases). For medial to total force ratio, R(2) was 0.69 for all trials together and between 0.54 and 0.90 for each trial separately (p < 0.001 in all cases). When only the stance phase was analyzed, R(2) values were slightly lower. These results support the hypothesis that the knee adduction torque is highly correlated with medial compartment contact force and medial to total force ratio during gait.

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    • "As such, reducing tibiofemoral joint contact forces in the medial compartment may be especially beneficial to runners who are either at-risk for the development or have already developed medial compartmental osteoarthritis. While the knee external adduction moment is widely used as a surrogate for in vivo contact loads in the medial compartment (Zhao et al., 2007), considering the frontal and sagittal plane knee moments together likely provides a better estimate of medial compartment loading (Manal, Gardinier, Buchanan, & Snyder-Mackler, 2015; Meyer et al., 2013). "
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    ABSTRACT: We evaluated the efficacy of an in-field gait retraining programme using mobile biofeedback to reduce cumulative and peak tibiofemoral loads during running. Thirty runners were randomised to either a retraining group or control group. Retrainers were asked to increase their step rate by 7.5% over preferred in response to real-time feedback provided by a wrist mounted running computer for 8 routine in-field runs. An inverse dynamics driven musculoskeletal model estimated total and medial tibiofemoral joint compartment contact forces. Peak and impulse per step total tibiofemoral contact forces were immediately reduced by 7.6% and 10.6%, respectively (P < 0.001). Similarly, medial tibiofemoral compartment peak and impulse per step tibiofemoral contact forces were reduced by 8.2% and 10.6%, respectively (P < 0.001). Interestingly, no changes were found in knee adduction moment measures. Post gait retraining, reductions in medial tibiofemoral compartment peak and impulse per step tibiofemoral contact force were still present (P < 0.01). At the 1-month post-retraining follow-up, these reductions remained (P < 0.05). With these per stance reductions in tibiofemoral contact forces in mind, cumulative tibiofemoral contact forces did not change due to the estimated increase in number of steps to run 1 km.
    Full-text · Article · Dec 2015 · Journal of Sports Sciences
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    • "Biomech. (2015), between the medial and lateral compartment is 55–45% (Zhao et al., 2007). Thirdly, in comparison with the native femoral condyle, a hemi-TKA reduces the contact area to 30% (Zdero et al., 2001) and in order to apply a comparable contact pressure to the native femoral condyle the force for the hemi-TKA was reduced correspondingly. "
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    ABSTRACT: Isolated tibial plateau impression fractures can be reduced through minimally invasive techniques using balloon inflation and cement augmentation. No evidence exists yet if an additional fixation at all and which method of fixation is necessary in the treatment of these fractures. The purpose of this study was to compare a locking plate and a screw raft for additional fixation after balloon reduction and cement augmentation in isolated tibial plateau impression fractures. Loss of reduction was subsequently analysed without additional fixation. Lateral tibial plateau impression fractures were created in eight matched pairs of human cadaveric tibiae. Reduction was performed using a balloon inflation system, followed by cement augmentation. Additional fixation was performed with a lateral locking plate or a screw raft (four 3.5-mm screws). Specimens were cyclically loaded at 20-240N, 20-360N and 20-480N. Subsequently, additional fixation was removed and the last cyclic interval (20-480N) repeated. Loss of reduction was assessed by measuring subsidence of the subchondral bone. Fractures treated with plate fixation exhibited less subsidence at higher loads compared with those treated with screw raft fixation (P<0.05). Loss of reduction significantly increased after removal of the additional fixation. This experimental study suggests that loss of reduction can be minimised by using locking plate fixation after balloon reduction and cement augmentation in the treatment of isolated tibial plateau impression fractures. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Full-text · Article · Jun 2015 · Clinical biomechanics (Bristol, Avon)
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    • "The external knee adduction moment (KAM) reflects the dynamic load on the medial compartment, and is a predictor for the risk of progression for the medial compartment OA (Andriacchi and Mundermann, 2006; Benell et al., 2011; Miyazaki et al., 2002). Researchers have used force-measuring knee implants to validate the KAM as a surrogate measure of medial knee loading (Zhao et al., 2007), and KAM has been found to be adequately reliable as an outcome measure (Birmingham et al., 2007). "
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    ABSTRACT: Background Lateral foot wedges represent a biomechanical intervention aimed at reducing medial knee loads. However, the effects of varying wedge amounts on biomechanical variables and orthotic comfort have not been systematically studied. Further, arch height may influence the comfort of laterally wedged devices. Therefore, the primary purpose of this study was to examine the effect of incrementally increasing lateral wedge amounts on knee adduction moment parameters and subjective comfort. The secondary purpose was to relate arch height measures to the comfort of the devices. Methods Twenty-five healthy subjects underwent three-dimensional instrumented gait analysis testing using seven inclinations of lateral wedging (0°, 2°, 4°, 6°, 8°, 10°, 12°). Subjects reported comfort level for each orthotic condition. Arch heights were measured in standing and sitting, and rigidity index and stiffness were calculated. Findings The knee adduction moment decreased with wedge amounts up to 6°, but more aggressive amounts did not yield additional reductions. Comfort ratings did not change from baseline until wedge amounts exceeded 8°. In addition, arch height measures, arch rigidity index and stiffness did not relate to the comfort of the orthotic device regardless of the wedge amount. Interpretation Knee adduction moment decreased with mild wedge amounts while maintaining comfort. Wedge amounts greater than 6° yielded little additional mechanical benefit and amounts greater than 8° compromised comfort. It appears that 4°–6° of lateral wedging are optimal in regard to desirable biomechanical change and comfort level in healthy individuals.
    Full-text · Article · Sep 2014 · Clinical Biomechanics
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