Complex Primary Total Knee Arthroplasty for Severe Bilateral Genu Varum with Fixed Flexion Deformity: Mechanical Axis Restoration, Soft-tissue Balancing, and Functional Recovery

Abstract

Severe bilateral genu varum associated with end-stage medial compartment osteoarthritis is a technically demanding indication for total knee arthroplasty (TKA). The principal reconstructive problems are fixed coronal malalignment, medial soft-tissue contracture, posterior osteophytes, flexion contracture, asymmetric tibial bone loss, and the need to obtain rectangular flexion and extension gaps without causing postoperative instability. A 50-year-old male presented with progressive bilateral knee pain for 1 year, more severe on the right side, with difficulty in walking, stair climbing, squatting, and sitting cross-legged. He had no history of trauma, inflammatory arthritis, diabetes, hypertension, or cardiovascular disease. Examination showed bilateral swelling, diffuse tenderness, obvious genu varum, fixed flexion deformity of 25° in both knees, and preserved distal neurovascular status. Radiographs showed Kellgren-Lawrence grade IV osteoarthritis with complete medial joint-space loss, osteophytes, tibial beaking, and approximately 22° of varus malalignment on long-leg assessment. Intervention: After routine medical optimization, simultaneous bilateral cemented posterior-stabilized TKA was performed through a medial parapatellar approach. Correction was achieved using measured bone resections, removal of medial/posterior osteophytes, sequential medial release, posterior cruciate ligament sacrifice, 3° posterior tibial slope, and equalization of 18-mm flexion and extension gaps. Outcome: Mobilization began on the postoperative day 1 and discharge occurred on day 5. At 1 year, the patient had painless independent ambulation, stable knees, full extension, 120° of flexion, near-neutral alignment, Knee Society knee score improvement from 45 to 90, function score improvement from 40 to 85, and VAS pain reduction from 8/10 to 1/10. No infection, thromboembolism, instability, or early radiological complication occurred. This case highlights that severe bilateral varus knees can be corrected with simultaneous bilateral Posterior-stabilized PS-TKA in carefully selected patients when preoperative planning, systematic bone resection, medial release, and gap balancing are executed meticulously.