Case 2: 54 year old male with progressively worsening left knee pain.
Case Discussion:
There is extensive bone marrow edema in the medial femoral condyle. On the T1-weighted image and sagittal PD and PD FS images, a curvilinear band of low signal is present in the subchondral bone just deep to the articular surface, consistent with a fracture line.
Expert Commentary:
This entity was previously called "spontaneous osteonecrosis of the knee, or SONK. It has been recognized that osseous stress or insufficiency fractures are fairly common in the subchondral bone of the knee, and that osteonecrosis is not the primary etiology in most cases with this appearance.
However, if the patient continues to weight-bear and the fracture does not heal, it may lead to osteonecrotic tissue at the fracture interface and can ultimately lead to articular collapse.
Case Discussion: