Osteonecrosis of the intercondylar spines of the tibia

Osteochondritis dissecans (OCD or OD) is a joint disorder primarily of the subchondral bone in which cracks form in the articular cartilage and the underlying subchondral bone. OCD usually causes pain during and after sports. [Source: Wikipedia ]

Caffey tibial spine osteonecrosis
Is A
Site-specific avascular necrosis