Pilot testing of a variable stiffness transverse plane adapter for lower limb amputees

Area of Science:

• Biomechanics
• Prosthetics and Orthotics

Background:

• Amputees often suffer soft tissue breakdown and discomfort due to shear stresses between the residual limb and prosthesis.
• High transverse plane shear stresses are a significant challenge in prosthetic limb use.

Purpose of the Study:

• To evaluate the impact of varying transverse plane stiffness on shear stresses in lower limb amputees.
• To assess the efficacy of a novel variable stiffness torsion adapter (VSTA) in mitigating these stresses.

Main Methods:

• A small cohort of lower limb amputees tested a VSTA at three stiffness levels (compliant, intermediate, stiff).
• Participants performed daily living tasks emphasizing transverse plane motion, including walking and turning.
• Peak transverse plane moments were measured during these tasks.

Main Results:

• The compliant VSTA setting significantly reduced peak transverse plane moments during 90° and 180° turns compared to the stiff setting.
• No significant loss of mobility was observed at self-selected walking speeds across the different stiffness settings.
• The VSTA demonstrated potential for reducing socket-limb interface stresses.

Conclusions:

• Variable stiffness adapters may help reduce residual limb stresses and discomfort for amputees.
• Further research into VSTA technology could improve prosthetic comfort and reduce soft tissue issues.