Is trabecular bone score less affected by degenerative-changes at the spine than lumbar spine BMD?

Summary: It has been established that degenerative-changes at the spine elevate bone mineral density at the lumbar spine. This study in men reports that trabecular bone score may be less affected by spinal degenerative-changes. Purpose: A recent tool for assessing trabecular microarchitecture at the lumbar spine, trabecular bone score (TBS), provides information about bone health complementary to lumbar spine areal BMD (here referred to as BMD). In men, mean BMD increases with increasing age due to degenerative-changes at the spine including osteophytes and aortic calcification. The aim of this study was to investigate whether TBS is similarly affected by the presence of degenerative-changes in men. Methods: This study included 728 men aged 40–90 years enrolled in the Geelong Osteoporosis Study. Lumbar spine DXA scans (Lunar Prodigy) were used to determine TBS retrospectively (TBS iNsight software, Version 2.2), and for identification of degenerative-changes. Using multivariable regression techniques, the relationships between TBS or BMD and degenerative-changes were assessed, further adjusting for age and weight. The difference between each of the two methods was examined through testing interactions between method, degenerative-changes and age. Results: Of 728 men, 439 (60.3%) were identified as having one or more degenerative-changes at the lumbar spine. Adjusted mean TBS was 1.219 (1.203–1.232) and 1.196 (1.179–1.212) for those with and without degenerative-changes, respectively. Adjusted mean BMD was 1.317 g/cm (1.297–1.336) and 1.198 g/cm (1.173–1.223) for those with and without degenerative-changes, respectively. Partial r for degenerative-changes in the model for TBS was 0.076 and for BMD, 0.257 (both p < 0.05). The three-way interaction between method, degenerative-changes and age was significant (p = 0.05) indicating significant effect of artefacts on the standardised values, affected by age and method. Conclusion: This study suggests that TBS is less affected by degenerative-changes at the spine than is BMD. Thus, TBS may prove useful in the assessment of fracture risk in men with degenerative-changes at the spine.