Patellar instability MENISCI: No significant abnormality noted.ARTICULAR CARTILAGE AND BONE: The articular cartilage of the medial and lateral compartments is preserved. There is slight depression of the lateral femoral condyle which may relate to prior injury. A small amount of marrow signal is seen along the lateral femoral condyle presumably from prior patellar subluxation.There is a obliquely oriented linear defect involving the medial portion of the patella representing a nondisplaced fracture. Marrow edema is seen along the fracture site although the underlying articular cartilage of the patellofemoral compartment is intact. The femoral trochlea appears slightly shallow and dysplastic. The MPFL is torn.LIGAMENTS: The ACL is absent. The PCL and remaining collateral ligaments are intact.EXTENSOR MECHANISM: There is patella alta although the patellar tendon is intact. A mild amount of edema-type signal surrounds the anterior soft tissues of the knee.ADDITIONAL
1. Ruptured ACL.2. Oblique, nondisplaced fracture of the patella.3. Findings consistent with prior patellar subluxation including bony contusions of the patella and lateral femoral condyle, shallow appearance of the femoral trochlea, and tearing of the MPFL.