Ahlback disease

Spontaneous osteonecrosis of the Knee, is the result of vascular arterial insufficiency to the medial femoral condyle of the knee resulting in necrosis and destruction of bone. It is often unilateral and can be associated with a meniscal tear. [Source: Wikipedia ]

Osteonecrosis of the femoral condyle in adults
Is A
Site-specific avascular necrosis