Patellar tendon rupture as a first presentation for undiagnosed primary hyperparathyroidism

Abstract

Introduction: patellar tendon rupture is usually traumatic in origin; however, spontaneous or atraumatic rupture is uncommon and often signify underlying pathological processes involving the tendon substance. One of these pathological processes is primary hyperparathyroidism. Case presentation: In this case report we present a unique case of a patient not diagnosed previously with hyperparathyroidism. The patient's initial presentation was atraumatic knee pain and knee extension weakness, imaging studies showed complete avulsion of the patellar tendon from its tibial footprint. Another clinical finding was an index finger swelling, which, after laboratory and imaging studies of the parathyroid gland, turned out to be brown tumor of undiagnosed primary hyperparathyroidism. The patient underwent excision of the parathyroid adenoma, and repair of the patellar tendon using semitendinosus tendon graft and intraosseous tibial anchors at the footprint. Patient regained pain-free and good movement of her knee. Conclusion: Atraumatic patellar tendon rupture, especially in the absence of renal impairments should raise the suspicion of pathological process involving the tendon substance, this should alert the orthopedic surgeon to look for secondary causes of degeneration of the tendon substance, of which hyperparathyroidism is an important differential diagnosis.