Patellar and quadriceps tendon rupture are associated with hip fracture in hemodialysis patients with severe hyperparathyroidism

Spontaneous rupture of the patellar (PTR) and quadriceps (QTR) tendon are infrequent. Systemic diseases such as diabetes mellitus, chronic kidney disease and secondary hyperparathyroidism (SHPT) are risk factors. The present cohort study aimed to evaluate risk factors associated with tendon rupture in hemodialysis (HD) patients with SHPT, as well as outcomes including surgical complications, re-ruptures and fracture. Baseline clinical, laboratorial data and radiographs were analyzed. Patients were followed up from March 2012 to March 2020. One-hundred thirty-one patients (≥18 years of age, on HD ≥ 6 months, with SHPT) were included. Incidence rates of PTR and QTR were 2.3 and 1.7/10000 HD patients/year, respectively. The mean age of patients with tendon rupture was 44.0 ± 11.2 years. These patients exhibited higher serum levels of phosphorus (6.3 ± 1.5 mg/dL vs 5.6 ± 1.1 mg/dL; p = 0.005), parathyroid hormone (2025.7 ± 667.6 pg/mL vs 1728.4 ± 684.8 pg/mL; p = 0.035), and C-reactive-protein (35.4 ± 32.9 mg/dL vs 17 ± 24.5 mg/dL; p = 0.002) compared to the group without tendon rupture. The mean follow-up was 56.7 ± 27.1 months. No patient required a new surgical approach or experienced re-rupture. Of all patients, 31% experienced hip fracture: 50% in the group with rupture (29.5 ± 17.4 months after the tendon rupture) vs 26% without tendon rupture (p = 0.015). After adjustment, the hazard ratio for hip fracture was 2.87 (CI 95% 1.27–6.49; p = 0.012). Patients with SHPT and high levels of phosphorus, parathyroid hormone, and inflammatory markers were at greater risk for tendon rupture. Surgical complication rates were low. However, results suggest that tendon rupture of knee extensor mechanism in hemodialysis patient with SHPT should be regarded as a “red flag” for future hip fracture.