Abstract
<title>Abstract</title> <p>Background: Osteonecrosis of the lateral femoral condyle is a rare condition, and the optimal surgical management for extensive, deep lesions in young or active patients remains a matter of debate. Both unicompartmental knee arthroplasty and total knee arthroplasty raise concerns regarding implant longevity in this population, making joint-preserving surgical strategies desirable. Case presentation: A 52-year-old man with a history of 10-year corticosteroid use was presented with pain on the lateral side of his left knee. Massive osteonecrosis of the lateral femoral condyle (approximately 25 × 30 × 15 mm), with concomitant mild valgus malalignment (hip-knee-ankle angle 4°) and a horizontal tear of the lateral meniscus was detected with the radiographical and computed tomography examinations. The patient underwent a combination of autologous osteochondral en bloc transplantation (OCET) of a mass graft which was harvested from the medial trochlea (approximately 20 × 25 × 18 mm) and fixed with four double-threaded screws, arthroscopic lateral meniscus repair, and medial closing-wedge distal femoral osteotomy (DFO) with a correction angle of 5°. At two years postoperatively, we confirmed solid union at both the osteotomy and graft sites with no loss of alignment correction (femorotibial angle 176°, hip-knee-ankle angle -2°), and observed marked improvement in his knee pain, the visual analogue scale score, and all subscales of the Knee Injury and Osteoarthritis Outcome Score. Conclusions: The combination of OCET and DFO were shown to be an effective and reliable joint-preserving treatment strategy for extensive and deep osteonecrosis of the lateral femoral condyle with concomitant valgus malalignment in young, active patients, while the long-term follow-up is necessary to evaluate durability.</p>