These are findings of osteochondritis dissecans (Konig disease) - with an intra-articular non-dislocated fragment, in accordance to the osteochondritis dissecans surgical staging system stage III.
There were specific complaints to suspect this pathology: pain increasing with knee joint motion, which is thought to be caused by intra-articular fragment impaction onto well innervated knee joint structures.
Osteochondritis dissecans occurs most often in children and adolescents, and most commonly in the knee joint, but also can be seen in the elbows and ankles, and other joints such as the talus. Estimated prevalence in the knee is 15 to 29 per 100,000 individuals.
The exact cause of osteochondritis dissecans is unknown. The reduced blood flow to the epiphysis of the affected bone might result from repetitive trauma — small, multiple episodes of minor, unrecognised injury that damage the bone. There might be a genetic component, making some people more prone to the disorder. There are some ongoing trials concerning genetic changes.