An investigation into the relationship between knee axis alignment and swing phase whip during trans-femoral amputee gait
Lateral whip, which is defined as sideward motion of the prosthetic heel away from theline of progression during swing phase of gait, is one of the common gait deviations thattrans-femoral amputees exhibit during walking. It poses several negative gaitcharacteristics to trans-femoral amputees. Changing the prosthetic knee axis alignmentin the coronal and transverse plane so that it is adducted (moved downwards medially)and / or externally rotated (moved backwards laterally) is hypothesised to reduce lateralwhip. This thesis tests and discusses this hypothesis and the effects of changingprosthetic knee axis alignment on the general gait pattern of trans-femoral amputees.One trans-femoral amputee who had his limb amputated due to chondro-fibro sarcomaparticipated in the current study. Infra-red camera system and force plates were used tocollect kinematic and kinetic data of the gait of the amputee participant under fourdifferent alignment conditions. The effects of changing prosthetic knee axis alignmentin the coronal and transverse plane on lateral whip gait deviation in particular and on thegait pattern in general, were analysed. The four alignment conditions are:A) Standard - 00° adduction - 05°external rotationB) Adduction - 20° adduction 05° external rotationC) Rotation - 00° adduction - 10° external rotationD) Adduction & Rotation - 20° adduction 10° external rotationWalking trials under each alignment condition were first analysed using Qualisys TrackManager (QTM, Qualisys Sweden). Data filtering and gait parameters calculation wereobtained using Visual 3D software (C-motion, USA). The data were then statisticallyprocessed using SPSS (SPSS Inc, USA).It was found that conditions (B, C and D) resulted in a significant reduction in lateralwhip, with condition (C) resulting in the largest reduction. The reduction in lateral whipis most likely to be the result of significantly increased external rotation (reduction ofinternal rotation) of prosthetic side hip joint that occurred in swing in conditions (B, Cand D). Conditions (B and D) however, caused maximum knee flexion during swing tobe significantly less than in conditions A and C. Another finding was that the pelvis of the amputee subject is significantly more anteriorly rotated than in condition A.
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