Total knee arthroplasty conversion after a failed lateral closing wedge high tibial osteotomy with knee hyperextension and secondary ankle degeneration

RATIONALE High tibial osteotomy (HTO) has been used widely for medial compartment knee osteoarthritis to correct the deformity and relieve symptoms, especially in young patients who are willing to maintain the high activity level. However, the change of bone morphology, ligament imbalance, limb malalignment, and other complications may influence the short-term outcomes of HTO. Some cases may even require conversion to TKA shortly after HTO because of the loss of correction or pain due to accelerated osteoarthritis. PATIENT CONCERNS A 43-year-old female patient presented with persistent pain of both the left knee and the ankle. She underwent a lateral closing wedge HTO two years ago. Radiographies showed The Kellgren-Lawrence (K-L) grade IV osteoarthritic change and hyperextension (HE) of the left knee and the degeneration of the left ankle. DIAGNOSES A failed lateral closing wedge high tibial osteotomy with knee hyperextension and secondary ankle degeneration. INTERVENTION A posterior-stabilized TKA conversion and postoperative rehabilitation were performed. OUTCOMES The operation corrected the HE deformity and relieved the pain at the level of the left knee. However, the secondary change of the left ankle was irreversible. LESSONS A failed lateral closing wedge HTO might speed up the degeneration of the knee and increase extra technical issues in the following TKA. What is more, the secondary osteoarthritis and deformity of the ankle cannot be ignored.