Not a typical case of bilateral knee osteoarthritis

A 64 year old woman presented to our clinic with intermittent bilateral knee pain for several years. She described her pain as mild, diffuse, both improved and worsened with walking, and occasionally associated with a sensation of instability. Although she had no history of trauma, mechanical symptoms such as locking, interference with daily activities, or pain in other joints, she did have osteoarthritis of the knee and osteoporosis. Several years earlier she had received a corticosteroid injection in her left knee but had never undergone imaging of her knees. Recently, she had been using paracetamol (acetaminophen) and naproxen as needed for the pain.

Physical examination showed bilateral genu valgum with bilateral diffuse tenderness to palpation along her joint lines and patellar facets. Bilateral patellar movement caused considerable crepitus and discomfort. She had a small joint effusion in her left knee but not on the right. She had decreased flexion of the knees—110º on the left and 100º on the right. Her gait was mildly antalgic bilaterally. Plain radiography was performed (fig 1⇓).