Presentation
Traumatic patellar dislocation 2 days ago. Knee pain.
Patient Data
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MR shows large joint effusion in suprapatellar bursa with fat-fluid level (lipohemarthrosis).
There is an osteochondral fragment floating within the suprapatellar bursa which is isointense with bone structures in all sequences. There is an articular cartilage defect at the medial patellar facet with adjacent bone marrow edema. The patella is laterally subluxed.
The bone marrow edema at lateral femoral condyle and grade II medial patellar retinaculum injury secondary to lateral patellar dislocation.
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Red arrow and asterisk indicate osteochondral fragment.
Case Discussion
Osteochondral fractures of the patella are commonly associated with acute patellar dislocations. In most cases, the osteochondral fracture is located in the medial facet of the patella.