Evaluation of a variable resistance orthotic knee joint

Area of Science:

• Orthotics and Biomechanics
• Rehabilitation Engineering
• Assistive Device Technology

Background:

• Knee-ankle-foot orthoses (KAFOs) traditionally limit natural gait and are mainly for level walking.
• Existing KAFOs can cause unnatural gait patterns due to fixed knee support.
• Knee extensor weakness necessitates supportive bracing for ambulation.

Purpose of the Study:

• To evaluate the functional performance of the novel Ottawalk-Variable Speed (OWVS) orthotic knee joint.
• To assess the OWVS's efficacy in controlling knee flexion during walking and stair descent.
• To determine the feasibility of variable resistance for diverse terrain negotiation in KAFOs.

Main Methods:

• A pilot study using a carbon-fiber KAFO with a standard single-axis knee joint (medial) and the OWVS joint (lateral).
• An able-bodied participant performed level ground walking (stance-control, open, closed) and stair descent.
• Manual mode switching (closed to open) was tested for stance-control walking; knee kinematics and stair descent performance were recorded.

Main Results:

• The OWVS successfully controlled knee flexion during stance and stair descent with a single lateral joint.
• Mode switching between closed and open settings was rapid and functional for stance-control walking.
• Stair descent was supported by OWVS resistance, though range of motion was reduced compared to the open setting.

Conclusions:

• The Ottawalk-Variable Speed (OWVS) KAFO demonstrates potential for controlled knee flexion during ambulation and stair descent.
• The microprocessor-controlled, low-profile design with variable resistance may enhance mobility across varied terrains.
• This novel orthotic knee joint offers a promising advancement in assistive devices for individuals with knee extensor weakness.