A 31-year-old man presented with left knee pain and knee locking that occurred only with flexion during squatting exercises at the gym. Eighteen years earlier, he had sustained a blow to the outstretched knee in a lacrosse event. He had been managed with immobilization followed by 3 months of physical therapy.
On physical examination at presentation, a nodule was noted to be mobile with the knee in the flexed position. The nodule would move distally and then lock the knee, with maximum flexion of the knee. To unlock, the knee had to be flexed and the nodule would have to be manipulated in the proximal and anterior directions, thus allowing for full mobility. The physical examination of the knee was otherwise negative with intact ligaments.
Imaging included radiographs that demonstrated a 1.2 × 1.6 cm nodule lateral to the left femoral condyle (Figs. 1-A and 1-B). Follow-up magnetic resonance imaging (MRI) scans showed the nodule in the popliteus sulcus, thinning of the popliteus tendon, and a trace joint effusion (Figs. 2-A and 2-B). The decision was made to excise the nodule.
Arthroscopy of the knee was performed with standard anteromedial and anterolateral portals. Diagnostic arthroscopy demonstrated intact chondral surfaces with no meniscal abnormalities. The cruciate ligaments were intact. The lateral gutter was examined, and the nodule was found to be extra-articular. It was decided to proceed with open excision.
Next, an incision was made centered over the lateral epicondyle. The iliotibial band was split, and the nodule was identified and delivered bluntly (Figs. 3-A and 3-B). The wound was closed in a layered fashion.
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