Osteochondral necrosis of the medial femoral condyle: 12 foals, including three survivors (2020–2025)

Summary Background Osteochondral necrosis of the medial femoral condyle (ON MFC) is an uncommon disease in foals, usually resulting in euthanasia. Objective To describe the characteristics of foals with ON MFC. To determine if a radiographic grading system of ON MFC may help to assess prognosis. Study Design Retrospective case series. Methods Medical records of Thoroughbred foals presented for hindlimb lameness and diagnosed with ON MFC between 2020 and 2025 were reviewed. History, clinical signs, results of haematology, Serum Amyloid A concentration and synovial fluid analysis, radiography and computed tomography and treatment and outcome were recorded. A radiographic grading system for ON MFC was devised. Gross post‐mortem and histopathology examinations were performed. Results Six foals had no history of disease until acute onset of severe hindlimb lameness; six had previous medical problems. Higher lameness grades were associated with a poor prognosis. Synovial fluid analysis of the medial femorotibial joint was predominantly inflammatory ( n = 7). No foals had results consistent with septic arthritis. Radiography and computed tomography revealed an osteochondral flap or fragment with a typical caudo‐abaxial location in nine foals. Surgical treatment via arthroscopic debridement had a poor outcome. Conservative management was successful in three foals, with progressive improvement in lameness and resolution of radiographic abnormalities. There was no association between the radiographic grade of ON MFC and survival (all p > 0.05). Histopathology revealed predominantly inflammatory changes in two limbs and osteonecrosis in two limbs. Main Limitations The small number of foals, including some with incomplete information. Lack of comparative radiographic images of the contralateral limb and a control population. Conclusion Judicious case selection and monitoring progress clinically and radiographically may help to identify suitable candidates for successful conservative treatment.