The effect of step length alterations on intact limb medial tibiofemoral joint contact force in individuals with unilateral lower limb amputation.

INTRODUCTION

Individuals with lower limb amputation (LLA) frequently demonstrate intact limb knee osteoarthritis, likely from alterations in joint loading. Prior work suggests changes in step length (SL) may affect knee joint loading, however this has not been evaluated in this population. Therefore, the purpose of this study was to examine the effect of SL changes on intact limb medial compartment tibiofemoral joint contact force (mTJCF) in individuals with LLA.

METHODS

Fourteen individuals with transtibial amputation walked at their self-selected velocity for three step length conditions: self-selected (SLSS), 15 % increased (SLI), and 15 % decreased (SLD). Ten gait cycles from each condition were analyzed using standard OpenSim procedures. Intact limb mTJCF 1st Peaks, 2nd Peaks, and Impulses were compared between conditions using linear mixed effects models.

RESULTS

1st Peak was increased during SLI compared to SLSS (2.65 BW vs. 2.39 BW, p = 0.02). 2nd Peak was reduced during SLD compared to SLSS (2.61 BW vs. 2.94 BW, p < 0.01) and SLI (2.61 BW vs. 3.05 BW, p < 0.01). Impulse was different between all conditions (SLSS: 1.35 ± 0.29 BW-s, SLI: 1.61 ± 0.33 BW-s, SLD: 1.14 ± 0.35 BW-s, all p < 0.01). All other comparisons were non-significant.

CONCLUSION

Changes in SL altered intact limb mTJCF of individuals with LLA, though whether these changes are clinically meaningful is unknown. Clinicians should consider such effects when performing interventions that may alter SL.