In Situ Leg Length Measurement Technique in Hip Arthroplasty
In Situ Leg Length Measurement Technique in Hip Arthroplasty ..
The clamshell devices restored the distal excursion of the CoP () such that the peak GRFs () were borne by the prosthetic forefoot well beyond the distal end of the residuum (40% of shoe length). As such, the peak ankle joint moment () and peak knee flexion moment () were comparable to those observed in the control sample. The clamshell devices were constructed with a rigid socket that encompassed the residuum and leg segments such that the device eliminated ankle motion. The forefeet of these devices were made either from the distal portion of a prosthetic forefoot or had a solid laminated section out to the toe-break (). The devices restored the effective foot length, because they incorporated a stiff forefoot capable of supporting the amputee's body mass during loading and a socket that could comfortably distribute the forces caused by loading the toe lever . Immobilizing the ankle meant that the foot segment and tibial shell were rigidly linked, and as such, the device could moderate the moments caused by loading the toe lever. If the device were to allow ankle motion, then the moments caused by loading the toe lever would need to be controlled by the calf musculature; should this not be possible (either through weakness or discomfort on the residual foot caused by contraction of these muscles), then the persons with amputation would likely not be able to load the prosthetic forefoot in this way.
In situ leg length measurement allows accurate ..
The limited distal excursion of the CoP commensurate with the peak GRF led to reductions in the ankle plantar flexion moment () and the absence of a knee flexion moment following midstance (). Persons with TMT and Lisfranc amputation may moderate the external moments at the ankle and knee to compensate for atrophy and weakness of the cojoint ankle plantar flexors and knee flexors. Alternatively, this strategy could be a means of reducing plantar pressure and shear caused by contraction of the soleus and gastrocnemius musculature. Moreover, this adaptation may minimize the residual foot/socket interface pressures caused by loading the toe lever or may compensate for the prosthetic forefoot being too compliant .