Design and evaluation of an offloading orthosis for medial knee osteoarthritis

Knee osteoarthritis is an incurable degenerative joint disease that affects millions of people. Characterized by stiffness and knee pain in the early stages, it can cause loss of function and mobility. Most treatment options are either not sustainable, invasive, or costly. Alternatively, offloading knee orthoses are a cost-effective option that provides immediate pain relief when worn. Offloading knee orthoses, however, have low patient compliance rates. To improve patient compliance and optimize patient benefit, current orthosis designs must be enhanced to improve comfort, increase the perceived effect, and be adjustable to the patient. Consequently, this research presents the design, fabrication, and testing of a new offloading knee orthosis joint. The novel modular orthosis features an offloading mechanism intended to relieve the load on the joint solely during stance phase and reduce the moment during swing phase when offloading is not needed. Three-point bending tests of the experimental prototype demonstrated an offloading moment of 3.36 Nm, creating a noticeable offloading effect during stance, and reduced the moment to less than 0.5 Nm after 35° of knee flexion, thus, potentially increasing comfort during swing phase and sitting when offloading forces are not needed.