The Influence of Hydraulic Ankles and Microprocessor-control on the Biomechanics of Trans-tibial Amputees During Quiet Standing on a 5° Slope.

Michael Mcgrath,Piotr Laszczak,Katherine C Davies,Saeed Zahedi,Beata Rek,David Moser,Joe Mccarthy

doi:10.33137/cpoj.v2i2.33517

Michael Mcgrath, Piotr Laszczak + Show 5 more

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https://doi.org/10.33137/cpoj.v2i2.33517

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Abstract

Lower limb amputees have a high incidence of comorbidities, such as osteoarthritis, which are believed to be caused by kinetic asymmetries. A lack of prosthetic adaptation to different terrains requires kinematic compensations, which may influence these asymmetries. Six SIGAM grade E-F trans-tibial amputees (one bilateral) wore motion capture markers while standing on force plates, facing down a 5° slope. The participants were tested under three prosthetic conditions; a fixed attachment foot (FIX), a hydraulic ankle (HYD) and a microprocessor foot with a 'standing support' mode (MPF). The resultant ground reaction force (GRF) and support moment for prosthetic and sound limbs were chosen as outcome measures. These were compared between prosthetic conditions and to previously captured able-bodied control data. The distribution of GRF between sound and prosthetic limbs was not significantly affected by foot type. However, the MPF condition required fewer kinematic compensations, leading to a reduction in sound side support moment of 59% (p=0.001) and prosthetic side support moment of 43% (p=0.02) compared to FIX. For the bilateral participant, only the MPF positioned the GRF vector anterior to the knees, reducing the demand on the residual joints to maintain posture. For trans-tibial amputees, loading on lower limb joints is affected by prosthetic foot technology, due to the kinematic compensations required for slope adaptation. MPFs with 'standing support' might be considered reasonable and necessary for bilateral amputees, or amputees with stability problems due to the reduced biomechanical compensations evident.

Highlights

Musculoskeletal health problems are prevalent among lower limb amputees.[1,2,3,4] The consensus among biomechanists is that the inherent asymmetry of the body, along with reduced confidence and proprioception on the prosthetic side, leads to an unequal distribution of limb loading between the two limbs.[2,3,5] Excessive dependence on the sound limb for support can have a degenerative effect on the joints
Lower limb amputees have a high incidence of comorbidities, such as osteoarthritis, which are believed to be caused by kinetic asymmetries
The resultant ground reaction force (GRF) and support moment for prosthetic and sound limbs were chosen as outcome measures

Summary

Introduction

Musculoskeletal health problems are prevalent among lower limb amputees.[1,2,3,4] The consensus among biomechanists is that the inherent asymmetry of the body, along with reduced confidence and proprioception on the prosthetic side, leads to an unequal distribution of limb loading between the two limbs.[2,3,5] Excessive dependence on the sound limb for support can have a degenerative effect on the joints. OA presents in the sound knee joint, affecting between 12-66% of all lower limb amputees,[2,3,6] up to 23% are affected at the sound hip.[2,3] There are consequences for the residual side through reduced loading. Lower limb amputees have a high incidence of comorbidities, such as osteoarthritis, which are believed to be caused by kinetic asymmetries. A lack of prosthetic adaptation to different terrains requires kinematic compensations, which may influence these asymmetries

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