It usually occurs later in the disease, in stage III of the four-stage Ficat classification system. It appears as a curved subchondral radiolucent line that is  often found on the proximal femoral or humeral head.
In general, this condition tends to manifest at a later stage of the disease, within the context of the four-stage Ficat classification system. It often presents as a curved subchondral radiolucent line that is commonly observed on the proximal femoral or humeral head.