Trabecular bone score and its association with Cobb angle kyphosis in older men: a cross-sectional study for the Osteoporotic Fractures in Men (MrOS) Study

Hyperkyphosis (HK), or accentuated forward spinal curvature, commonly affects older people, although its causes are not completely understood. We tested whether a measure of bone quality, trabecular bone score (TBS), is associated with HK in 1997 older men, and determined that men with degraded TBS were more likely to have HK. Introduction While vertebral fractures and low bone mineral density (BMD) contribute to kyphosis progression, it is unknown whether the trabecular bone score (TBS) may provide additional information on bone quality that could influence the degree of kyphosis. We hypothesized that degraded TBS would be associated with hyperkyphosis (HK) defined as a Cobb angle > 50 degrees. Methods Using data from 1997 participants of the Osteoporotic Fractures in Men (MrOS) Study who had baseline TBS and Cobb angle kyphosis measured, we investigated whether men with degraded TBS were more likely to be hyperkyphotic, even after adjustment for BMD and prevalent vertebral fractures. Results Men were an average age of 74 +/- 6 (mean +/- SD) years with a mean kyphosis angle of 38.6 +/- 11.5 degrees, 295 (15%) were classified as hyperkyphotic, and 416 (21%) had degraded TBS. Compared with men with TBS > 1.2, men with degraded TBS were more likely to have HK (OR: 1.47, 95% CI: 1.06-2.06, p =0.02) after adjusting for age, clinic, race, BMI, hip BMD, and prevalent vertebral fracture. If spine instead of hip BMD was included in the model, the odds ratio decreased to 1.35 (95% CI: 0.97-1.89, p =0.08). Conclusions Older men with degraded TBS are more likely to have HK not explained by underlying vertebral fractures.