Mechanical Orthosis for Knee Osteoarthritis Patients to Correct Internal Knee Joint Warping and Achieve Normal Knee Joint Rotation Motion

Abstract Knee osteoarthritis (OA) is the most frequent form of lower limb arthritis. The severity of knee OA patients is graded, with moderate patients having deteriorating symptoms due to abnormal lower extremity alignment and poor lower leg rotation. To prevent the worsening of symptoms, orthoses are prescribed for patients with knee OA. Although conventional orthoses can either correct alignment or guide the rotation of the lower leg, it is difficult for them to achieve both corrective force and normal range of rotation. Therefore, an orthosis equipped with a mechanism that can simultaneously correct alignment and guide rotation of the lower leg is necessary. In this study, we focused on the relationship between the change in the tilt angle of the lower leg and the rotation of the tibia to enable both corrective force and the induction of rotation of the lower leg. We then developed a lower limb orthosis equipped with a mechanism to both correct alignment and normalize rotation. Finally, walking experiments with actual patients with knee OA demonstrate the effectiveness of the proposed mechanism in correcting abnormal alignment and guiding the patient to a regular rotation.