A rotator cuff rupture produces permanent osteoporosis in the affected extremity, but not in those with whom shoulder function has returned to normal

Abstract

Abstract Areal bone mineral density (BMD) and clinical status of 34 men treated surgically 9 years earlier for a rotator cuff rupture of the dominant side shoulder were determined. The BMD was measured at the lumbar spine (L2–L4) and the proximal humerus, humeral shaft, radial shaft, ulnar shaft, distal forearm, and hand of both extremities using a dual-energy X-ray absorptiometric (DXA) scanner. Thirty-four age-, height-, weight-, and profession-matched normal men (controls) were also measured. The patients' mean side-to-side BMD difference (dominant minus nondominant/nondominant × 100%) was significantly lower in the proximal humerus (patients −3.5% vs. controls +2.4%, p = 0.0002), humeral shaft (–2.6% vs. +1.6%, p = 0.0005), radial shaft (–0.4% vs. +1.9%, p = 0.0311), distal forearm (–0.2% vs. +2.4%, p = 0.0158), and hand (+2.3% vs. +4.0%, p = 0.0047). In the ulnar shaft, this difference was almost the same in the patients (–0.2%) and controls (+0.2%) (NS). Also, the lumbar spine BMD did not differ significantly between these groups (mean ± SD = 1.098 ± 0.148 g/cm2 in patients vs. 1.066 ± 0.156 g/cm2 in controls). In patients, the relative BMDs of the injured extremity did not significantly associate with the size of the rupture; time delay between the injury and the surgery; type of surgery and postoperative treatment; postoperative immobilization time; follow-up time; patient's age, muscle strength or pain assessment; and subjective assessment of shoulder function. However, they strongly associated with the objective assessment of the shoulder function: the better the observed function of the shoulder, the less bone loss caused by the injury. In proximal humerus, the side-to-side BMD difference averaged +2.0% in the patient group with “excellent” shoulder function, −3.3% in the “good” group, −5.3% in the “fair” group, and −11.5% in the “poor” group (p = 0.0012). In conclusion, a rotator cuff rupture results in permanently reduced BMD in the injured extremity, the reduction being greatest in the proximal parts of the extremity. The observed mean decreases (6% in the proximal humerus, 4% in the humeral shaft, and 3% in the distal forearm of the injured limb) are clinically important with respect to age-related bone loss of 1% per year after the age of peak bone mass. Additional follow-up is needed to determine any increased risk of osteoporotic fractures in the injured extremity. Recovery of normal shoulder function seems to be of great importance for good bone recovery.