A 15-year-old boy presented to the orthopaedic department after unsuccessful conservative management for an osteochondritis dissecans (OCD) lesion in the medial femoral condyle (MFC) of the left knee. He initially presented with pain during sports activities such as baseball. At the time of presentation, his height was 150 cm (approximately 2.8 SD below the Japanese age average), and his BMI was 22. The patient had a prior history of OCD in the right elbow at age 11. His father also had short stature (153 cm, -3.1 SD) and had a history of surgically treated OCDs in both knees after skeletal maturity. No other significant family history was noted.

On physical examination, there was no swelling, tenderness, joint laxity, or restriction of range of motion. The patient was able to perform daily activities and participate in school physical education without experiencing symptoms. Initial radiographs showed a Brückl stage III OCD lesion in the left MFC, confirmed on MRI as Nelson stage II. Conservative management (activity restriction) was advised; however, after 3 months, imaging showed progression to Brückl stage IV and Nelson stage III. Despite being asymptomatic at referral, another 3 months of conservative care showed no improvement. Arthroscopic drilling was performed using a 1.6 mm Kirschner wire to create 10 channels that reached the subchondral bone. Radiographic union was achieved by 3 months postoperatively, and sports activity was resumed. Fourteen months later, the patient sustained minor trauma to the anterior knee and developed pain with locking. While initial imaging was unremarkable, a repeat evaluation after 4 months revealed a lesion in the lateral femoral trochlea (Brückl stage V, Nelson stage IV).