Dr. Allison Schroeder, MD, RMSK, submitted this case, which has broadened my differential diagnosis and approach to the sonographic evaluation of posterolateral knee pain. The patient is a 66-year-old active individual that developed acute posterolateral knee pain and swelling while performing box jumps in physical therapy. Initially managed as a distal biceps femoris tendinopathy, but symptoms persisted, prompting a referral to Dr. Schroeder who performed a diagnostic ultrasound.
Ultrasound evaluation, including long and short-axis images, revealed a tear of the proximal lateral head of the gastrocnemius tendon (arrowheads) at its insertion onto the lateral femoral condyle (LFC).
For reference, I’ve included a normal long-axis image of the lateral head of the gastrocnemius tendon (arrowheads), along with the corresponding probe position.
A subsequent MRI confirmed the diagnosis.
This case highlights the importance of evaluating the proximal tendon of the lateral head of the gastrocnemius when assessing posterolateral knee pain.