Ankle-knee synchronous knee lock mechanism: a revision

Area of Science:

• Biomedical Engineering
• Rehabilitation Engineering
• Prosthetics and Orthotics

Background:

• Traditional above-knee (A-K) prostheses present challenges in energy expenditure and stability for users.
• Existing knee mechanisms often lack adaptability for diverse daily activities and gait phases.
• Alignment methods for A-K prostheses, particularly for short residual limbs, require optimization.

Purpose of the Study:

• To design and evaluate a novel endoskeletal A-K prosthesis featuring an ankle-knee synchronous mechanism.
• To reduce the energy cost for prosthetic wearers by revising the knee mechanism.
• To improve stability, security, and functional mobility for amputees.

Main Methods:

• Development of a new endoskeletal A-K prosthesis with a revised knee mechanism incorporating multiple locking positions.
• Integration of an anteriorly placed knee joint synchronized with the ankle joint.
• Implementation of a new alignment concept using a weight-bearing line, especially for short A-K amputees.
• Modification of the knee mechanism to include a bumper for swing phase impact and a coil spring for extension assistance, eliminating the need for an inertia control mechanism.

Main Results:

• The designed prosthesis offers an ankle-knee synchronous mechanism with multiple knee lock positions.
• The anterior knee placement and synchronous motion aid in stabilizing the knee and balancing the body during the stance phase of gait.
• The revised alignment method and simplified knee mechanism contribute to reduced energy cost and enhanced user security.
• Amputees can assume various postures, facilitating daily activities and improving overall mobility.

Conclusions:

• The novel A-K prosthesis with an ankle-knee synchronous mechanism effectively reduces energy cost and enhances gait stability.
• The new alignment strategy and simplified knee design offer significant benefits, particularly for individuals with short A-K residual limbs.
• This prosthetic design improves functional independence and quality of life for amputees by enabling diverse body postures and activities.