Magnetic resonance imaging-based cortical thickness as a predictor of osteoporosis in rotator cuff tears .

BACKGROUND: Osteoporosis is frequently unrecognised in patients undergoing rotator cuff repair. Shoulder magnetic resonance imaging (MRI), already standard of care, offers an opportunity for opportunistic osteoporosis screening.

OBJECTIVE: To evaluate whether proximal humeral cortical bone thickness on shoulder MRI can predict osteoporosis in patients with rotator cuff tears (RCTs).

METHODS: A retrospective, cross-sectional study included 130 female patients (mean age 68.8 ± 8.9 years) who underwent shoulder MRI and dual-energy X-ray absorptiometry (DXA) within 6 months. Average cortical bone thickness (CBTavg) and cortical bone thickness index (CBTg) were measured on coronal T1-weighted images. Patients were classified per World Health Organization DXA criteria (T-score ≤ -2.5) at the femur, the lumbar spine and either site (all-site). Only female patients were eligible for inclusion; no male data were collected.

RESULTS: CBTavg and CBTg were significantly lower in osteoporosis groups across all classification schemes. For femur DXA, CBTavg at 4.5 mm achieved 100% sensitivity and 86% specificity (area under the curve (AUC) = 0.955). For all-site osteoporosis, CBTg at 0.26 yielded 100% sensitivity and 87.8% specificity (AUC = 0.958).

CONCLUSION: MRI-derived proximal humeral cortical thickness is a promising osteoporosis screening tool in RCT patients. A CBTavg below 4.5 mm should prompt DXA referral, improving preoperative bone health assessment without added cost or radiation. These cut-offs require external validation before clinical implementation.