Prostheses for persons with lower-limb amputations: an extra joint increases range of motion

Area of Science:

• Prosthetics and Orthotics
• Rehabilitation Engineering
• Biomechanics

Background:

• Individuals with unilateral lower-limb amputation often experience functional limitations due to restricted joint range of motion in their prostheses.
• Pre-existing prosthetic designs may not adequately address specific functional deficits, impacting workplace and daily activities.
• Case studies highlight the need for customized solutions to overcome limitations in hip and knee flexion.

Observation:

• Two patients with unilateral lower-limb amputation presented with functional impairments related to inadequate hip and knee flexion.
• The first patient, a hemipelvectomy amputee, lacked sufficient hip flexion for professional activities.
• The second patient, with a transfemoral prosthesis, had insufficient knee flexion for tasks requiring kneeling.

Findings:

• The addition of a manual-locking, single-axis knee joint adjacent to the existing joint successfully enhanced range of motion in both cases.
• Hip flexion improved from 125 to 190 degrees in the hemipelvectomy patient.
• Knee flexion improved from 140 to 170 degrees in the transfemoral amputee patient.

Implications:

• The strategic addition of an extra joint is a viable and effective intervention for improving functional outcomes in amputees with range-of-motion deficits.
• This approach offers a potential solution for enhancing prosthetic performance and patient satisfaction.
• Further consideration of dual-joint prosthetics may be warranted for individuals experiencing functional limitations due to restricted joint mobility.