Clinical experience has shown that patients who undergo total knee arthroplasty (TKA) may develop ankle symptoms. This habilitation aimed to analyze if this phenomenon could be replicated in a clinical trial. Another goal was to understand the biomechanical mechanisms which are responsible for ankle pain after TKA. In retrospective as well as prospective clinical trials it could be proven that about 20-25 % of the patients after TKA developed ankle pain after TKA. Preoperatively, the presented studies here could show that the hind foot is unable to sufficiently compensate for high-grade frontal deformities of the knee which can ultimately lead to osteoarthritis at the ankle joint. In another publication on the preoperative status it could be demonstrated that high-grade frontal deformities at the knee joint do not induce ligamentous ankle instabilities. Risk factors for developing ankle pain after TKA were identified. Patients with varus knee osteoarthritis and increased ankle pain after TKA had an increased talar tilt on radiographs already before the operation which could not be corrected by TKA. Patients with valgus knee osteoarthritis and increased ankle pain after TKA had a pathologically lateralized gait line before the operation. These studies underscore the importance to clinically evaluate the ankle joint before TKA in order not to miss patients who could potentially develop ankle pain. Patients with varus knee osteoarthritis and a pathologically increased talar tilt could benefit from insoles with a lateral wedge if they develop ankle pain after TKA. Patients with valgus knee osteoarthritis and a pathologically lateralized gait pattern could be treated using physiotherapy.
