Bilateral Spontaneous and Simultaneous Rupture of the Patellar Tendon in Primary Hyperparathyroidism--A Case Report

　　　　　Bilateral patellar tendon rupture is a very rare entity. Most cases studies in the literature have been reported in patients with an underlying systemic condition, i.e. systemic lupus erythematosus, rheumatoid arthritis, or associated with history of steroid injection about the patellar tendon. We report a case with primary hyperparathyroidism due to parathyroid adenoma, who presented to be a bilateral simultaneous and spontaneous rupture without obvious trauma.