16-year-old boy comes in for evaluation of right knee pain that has been around for several years. He had been skateboarding five days ago, and since that time, his knee has been stuck and is not able to fully extend or flex. He states that he limps at school.
Lacks 20 degrees to full extension and at least 20-30 degrees from full flexion. He is tender over the medical joint line and medial femoral condyle. He has no ligamentous instability on anterior drawer, Lachman, or collateral ligament testing.
4/17/2007 right knee x-ray: There is a mild irregularity of the inferior aspect of the medial condyle. There is no obvious joint effusion. Normal alignment is maintained. Normal appearance of the visualized bony structures is otherwise noted. There are no obvious fractures. No radioopaque foreign body is identified.
9/26/2011 right knee x-ray (2007 knee XR comparison): Two views were obtained. There is a large osteochondral defect, which has increased in size and involves the lateral aspect of the medial femoral condyle. There is increased bony resorption when compared to the previous study. There is a knee joint effusion present. No acute bony abnormality is identified. Soft tissues appear intact.
10/13/2011 MRI right knee without contrast (comparison 9/26/2011): There is a large osteochondral defect in the medial femoral condyle with a free fragment floating between the tibia and fibula. There is a separate fragment floating in the joint space along the medial aspect of the distal femur, which I believe is a separate osteochondral defect. There is edema and areas of cystic change in the underlying bone at the fragment donor site in the medial femoral condyle. A large amount of fluid is present in the joint space consistent with effusion. The anterior and posterior cruciate ligaments have normal appearance. The medial and lateral meniscus appear intact. No abnormal signal at the medial or lateral collateral ligaments is identified. On axial images, the patella is centered between the femoral condyles.
Meniscus tear, anterior/posterior collateral ligament tear, patellofemoral pain syndrome, tibial fracture, Osgood-Schlatters disease, popliteal cyst rupture, and osteonecrosis.
Differentiating OCD from osteonecrosis is difficult, but the most significant clue is the age of the patient. Younger patients tend to develop OCD, and older patients tend to develop osteonecrosis.
Dx: Osteochondritis Dissecans, Stage IV
Dx Confirmed by: Confirmed by the Orthopaedic surgeon.
Arthroscopic surgery with removal of loose body and drilling of the lesion. Current recommendations include: fixation of the lesion, drilling of the site of the defect with removal of loose bodies, and autologous osteochondral mosaicplasty and autologous chondrocyte transplantation.
PMH: He had been diagnosed with osteochondritis dissecans four years ago; and, has been followed with plain x-rays, which showed no instability of the lesion.
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