The dorsal defect of the patella is a normal developmental variant, present in 0.3-1% of the population that can be mistaken with an osteochondral lesion. It is usually asymptomatic, but sometimes it can be a source of anterior knee pain. It is typically located in the superolateral aspect of the patella and usually presents with normal overlying cartilage. Healing may occur spontaneously.

This patient also had a distended pes anserina bursa (not shown), likely the cause of his medial knee pain, with the dorsal defect an incidental finding.