Quadriceps tendon ruptures in uremia.

Chronic renal failure and its sequelae, particularly secondary hyperparathyroidism, may be associated with spontaneous quadriceps tendon ruptures. This is a report of two cases of bilateral spontaneous simultaneous quadriceps tendon ruptures in uremia and a review of the literature. The level at which the tendon ruptures is inconstant. Light microscopy reveals nonspecific changes of degeneration and calcification. Under electron microscopy, the structure and maturity of collagen fibers are normal. The ruptures occur in patients younger than 40 years of age who reject medical treatment (i.e. oral phosphate binder) and have long-standing renal disease (mean = 12.3 years). The predisposing causes of rupture are unknown. An abnormality of collagen metabolism, ischemia, direct effects of parathormone, and dystrophic calcification are some of the possible contributory factors.