Ultrasound-Guided Lavage of a Popliteus Tendon Calcification.

Abstract

A 73-year-old woman presented with lateral knee pain ongoing for 7 months, which was exacerbated the week before ultrasound examination. Her pain was radiating proximally along the lateral thigh and distally over the lateral leg, and it increased with weight bearing. On examination, full knee extension and flexion past 50° were painful. Pain was also elicited with palpation of the posterolateral corner of the lateral femoral condyle. On ultrasound, a well-circumscribed calcification was identified in the proximal popliteus tendon (Figure 1). A knee radiograph also showed the intratendinous calcific deposition (Figure 2). The patient had no pain relief with a short course of nonsteroidal anti-inflammatory drugs and activity modification. An ultrasound-guided percutaneous lavage of the popliteus tendon calcification was performed (Supplementary Data Video 1). The patient reported 90% relief of her pain as soon as the procedure was completed, and she was pain free at the 1-month follow-up. The popliteus is a triangular-shaped muscle innervated by the tibial nerve forming part of the posterolateral corner of the knee. Its proximal tendinous origin inserts on a characteristic groove well visible on an axial ultrasound scan of the lateral femoral condyle [1]. Its muscular portion courses medially and obliquely to insert on the posterior tibia, just above the soleal line. Popliteus calcific tendinopathy is extremely rare, and only a few cases have been reported in the literature. They were treated either with a conservative approach such as oral analgesia [2] and corticosteroid injection [3, 4], or arthroscopic excision [5]. This is the first reported case of popliteus calcific tendinopathy successfully treated with a lavage.