Review Question - QID 219920

Treatment E represents the use of an osteochondral allograft (OCA) for the treatment of the patient's large (>6cm2) osteochondral defect in the setting of untreated osteochondritis dissecans.

Osteochondritis dissecans (OCD) is a pathologic lesion affecting articular cartilage and subchondral bone that most typically occurs on the posterolateral aspect of the medial femoral condyle and often has a variable clinical presentation. Patients often present with vague and poorly localized activity-related pain and recurrent knee effusions. Treatment for stable lesions in children with open physes involves restricted weight-bearing and bracing; however, failed non-operative management and clinical signs of instability merit operative intervention. Stable lesions (i.e., lesions without circumferential subchondral edema on MRI) can be treated with subchondral drilling/microfracture (Treatment B), particularly in skeletally immature patients, while unstable lesions require fixation with headless compression screws (Treatment D) when large (>2cm2) and acute. Chronic lesions that exceed 2 square centimeters (up to 4-6 square centimeters) can be treated with osteochondral autograft transfer (OATs) as seen in Treatment A, while lesions >6 square centimeters are more commonly treated with osteochondral allograft (OCA) transfer (Treatment E) or matrix-induced autologous chondrocyte implantation (MACI).

Carey et al. provide updated AAOS appropriate use criteria for the management of osteochondritis dissecans of the femoral condyle. The authors note that there is a paucity of high-quality evidence to guide the treatment of OCD of the femoral condyle; however, they conclude by noting that three treatments are considered "Appropriate," namely activity restriction, osteochondral autograft transfer, and osteochondral allograft transplantation, while three treatments are considered "May Be Appropriate," namely physical therapy, fragment excision and marrow stimulation, and autologous chondrocyte implantation (with or without bone grafting).

Shea et al. published an update on the management of osteochondritis dissecans of the femoral condyle. The authors reviewed the 64 patient scenarios and 12 treatments developed by the Writing Panel of the AAOS Appropriate Use Committee. They concluded that unsalvageable fragments can be defined by three features: (1) fragment consists of cartilage only (2) fragment consists of multiple pieces (3) fragment contains damaged or absent articular cartilage.

Figure A is an AP radiograph demonstrating a large osteochondritis dissecans lesion of the lateral aspect of the medial femoral condyle. Figures B and C are fluid-sensitive coronal and T1-weighted sagittal MRI images of a knee showing a large, chronic osteochondral defect of the medial femoral condyle. Figure D represents the following treatment options: (A) OATs (B) microfracture (C) HTO (D) internal fixation with a headless compression screw (E) OCA.

Incorrect Answers:
Answer 1: Treatment A represents an OATS, which is typically reserved for smaller defects (< 4-6 square centimeters) given the availability of non-articulating harvest sites on the distal femur.
Answer 2: Treatment B represents microfracture, which is reserved for small lesions in skeletally immature individuals.
Answer 3: Treatment C represents a medial opening wedge high-tibial osteotomy (HTO), which is used for varus-pattern osteoarthritis in young individuals; however, this patient has a normal MPTA and Mikulicz line that falls within normal limits indicating normal limb alignment.
Answer 4: Treatment D represents a headless compression screw, which is used to fix acute, unstable osteochondritis dissecans lesions.