Spontaneous rupture of the patellar and contralateral quadriceps tendons associated with secondary hyperparathyroidism in a patient receiving long-term dialysis.

Although spontaneous rupture of the extensor tendon of the knee is more likely to occur in uremic patients with secondary hyperparathyroidism, simultaneous ruptures of bilateral knee extensor tendons is a rarely reported condition. We describe a 30-year-old man with uremia who underwent subtotal parathyroidectomy because of secondary hyperparathyroidism with very high serum parathyroid hormone (PTH) level (1940.4 pg/mL). Two weeks later, he complained of a sharp pain in both knees without trauma when he walked downstairs with his left knee forward and right knee behind. Spontaneous simultaneous ruptures of the right patellar tendon and the left quadriceps tendon were diagnosed and surgically repaired. The mechanism of spontaneous tendon rupture in uremic patients with secondary hyperparathyroidism seems to be related to high PTH level which results in osteolytic bone resorption at the tendon insertion site. Early surgical repair, control of secondary hyperparathyroidism, early use of vitamin D analogs, and total parathyroidectomy with or without autotransplantation of part of the parathyroid gland, can treat and prevent tendon rupture or re-rupture with satisfactory results.