International Journal of Clinical & Medical Images

The patient was a 63 year old woman with a chief complaint of worsening right knee pain, which began 6 weeks prior while walking down a steep incline. Prior to symptom onset, the patient ran 6.5 km daily. The patient’s symptoms initially presented as tightness in the posterior aspect of the knee, but changed to a constant varying ache along the medial aspect of the knee with occasional sharp pain during ambulation. The patient also reported night pain and as well as morning stiffness. Radiographic findings were significant for mild degenerative changes with minimal medial joint space narrowing for the right knee (Figure 1).

The patient was treated with a corticosteroid injection, which only provided temporary minimal relief. Magnetic resonance imaging was subsequently ordered and revealed findings consistent with spontaneous osteonecrosis of the medial femoral condyle (Figure 2), which is a distinct form of osteonecrosis and usually demonstrates a subchondral fracture identifiable on magnetic resonance imaging. This can affect males or females but it more commonly affects older women and is typically characterized by the sudden onset of knee pain [1].

In general, the lesion is more commonly located in a femoral condyle and it is not usually associated with systemic disorders or previous corticosteroid therapy [1]. The patient attempted a course of conservative treatment including protected weightbearing with hyaluronic acid, and physical therapy. However, the patient did not respond to conservative management and is awaiting unicompartmental knee arthroplasty. Note: The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the US Air Force or Department of Defense.