Presentation
Pain and locking of the left knee.
Patient Data
The MRI sequences demonstrate a well-defined osteochondral defect of the lateral aspect of the medial femoral condyle with underlying edema of the bone marrow of low signal on T1WI, and high signal on PD fat sat.
The detached osteochondral fragment is displaced, seen in the anterior aspect of the intercondylar notch, anterior to the distal ACL of low signal on T1WI, and intermediate signal on PD fat sat.
Degenerated posterior horn of the medial meniscus, grade 2c (MRI grading system for meniscal signal intensity). Mild joint effusion is noted
ACL, PCL, and collateral ligaments are intact.
Case Discussion
MRI features of an unstable osteochondritis dissecans of the knee, considered as stage IV according to osteochondral injury staging.