Total Ankle Replacement Through a Lateral Transfibular Approach in Patients with Ipsilateral Knee Arthrodesis: Report of Two Cases

Background: Knee arthrodesis markedly alters lower limb biomechanics and creates a challenging scenario when associated with end-stage ankle osteoarthritis. No prior reports have specifically described treatment with total ankle replacement (TAR) in the presence of an ipsilateral fused knee. This study evaluated the feasibility and mid-term outcomes of TAR in this rare condition. Methods: Two patients with post-traumatic end-stage ankle osteoarthritis and long-standing knee arthrodesis underwent TAR using a lateral transfibular approach with a Zimmer Trabecular Metal™ implant. Surgical planning aimed to restore coronal and sagittal alignment. Postoperative management and rehabilitation were specifically adapted to the absence of knee motion, with emphasis on gait re-education. Clinical and radiographic follow-up was performed up to 36 months. Results: At final follow-up, both patients showed substantial pain reduction, improved ankle range of motion, and recovery of a stable, functional gait compatible with knee fusion. Imaging demonstrated well-aligned, stable components without loosening or subsidence. No major complications or reoperations occurred. Conclusions: Lateral transfibular TAR appears feasible and effective for end-stage ankle osteoarthritis in patients with ipsilateral knee arthrodesis, preserving ankle motion and supporting functional ambulation in this complex setting.