Osteochondritis dissecans (OCD) patella

This is a case of a 14 year old male who presents with chronic knee pain. Lateral radiograph of the knee demonstrates an osseous fragment arising from the articular surface of the patella. This is confirmed on the sunrise view of the patella and is indicated by the red arrow. Findings are consistent with an osteochondral lesion of the patella, also known as osteochondritis dessicans. The most common location for an osteochondral lesion of the knee is the lateral aspect of the medial femoral condyle. These lesions can be defined as either stable or unstable, depending on whether there is fluid undercutting the lesion or frank separation of the osseous fragment. On this radiograph, there is clear separation of the fragment with sclerosis of both the margins of the fragment as well as the native patella. These lesions can cause knee instability and early onset degenerative arthritis. These lesions may resected and the patient may undergo cartilage replacement with either a microfracture procedure or cartilage transplantation.