Acute calcific tendinopathy of the popliteus tendon: a rare case diagnosed using a multimodality imaging approach and treated conservatively

Acute calcific tendinopathy of the popliteus tendon is a rare medical entity associated with significant patient discomfort. We present the case of a previously healthy 48-year-old female who presented to the emergency department with acute onset of left knee pain. Initial radiographs revealed calcifications within the posterolateral compartment of the knee. Ultrasound imaging demonstrated a swollen and hypoechoic popliteus tendon with an increased color Doppler signal at the periphery of the tendon as well as calcification in the tendon and adjacent soft tissues. Subsequently performed MRI revealed a thickened and heterogeneous popliteus tendon near its femoral attachment with marked edematous changes surrounding the tendon. Local ultrasound-guided glucocorticoid injection had successful clinical results with no recurrence at 8-month follow-up. In this case report we review the literature for similar previously reported cases. This case report of popliteus tendon calcific tendinopathy provides comprehensive multimodality imaging findings and a description of its non-surgical management.