Children and yound adults
In order: medial femoral condyle, lateral femoral condyle, femoral trochlea and patella
Juvenile and adult types
Clinical features:
Pain and swelling
Intermittent catching, locking, giving-way
MR:
Features:
Anatomical loss - OCD
Heterogenous signal (low - intermediate)
Disruption of subchondral bone plate
Subchondral cyst
Marrow edema
Instability criteria: (De Smet et al)
1. High signal rim surrounding OCD - most sensitive sign, highly specific sign in adult, not in juvenile OCD
2. Cyst surrounding OCD - highly specific in adult type, not juvenile OCD
3. High T2 fracture line through articular cartilage overlying OCD, highly specific in adult and juvenile OCD
4. Fluid-filled OCD - least sensitive, highly specific in adult and juveline OCD
Very sensitive (nearly 100%) and highly specific, if all 4 criteria meet
Secondary signs of instability:
Single cyst of more than 5 mm - highly specific, less sensitive
Multple cysts - highly specific, less sensitive
References:
1. Kijowski, R et al. Juvenile versus Adult Osteochondritis Dissecans of the Knee: Appropriate MR Imaging Criteria for Instability. Radiology 2008;248:571-578
2. SCHENCK RC et al. Current Concept Review - Osteochondritis Dissecans. The Journal of Bone and Joint Surgery 78:439-56 (1996)
