Implausible high bone mass density scores as assessed at the lumbar spine by dual X-ray absorptiometry and their correlation with conventional X-ray studies

Introduction: Implausible high bone mass density (BMD) scores as assessed at the lumbar spine by dual X-ray absorptiometry (DXA) may be indicative of fractures. Therefore, BMD deviations of more than 10% of a vertebral body in comparison to adjacent vertebrae or a visibly smaller vertebral body size lead to the recommendation to perform conventional X-ray studies. However, degenerative disease of the vertebrae may also lead to false high DXA values. The portion of fractures or degenerative disease is not known amongst patients with implausible high BMD scores.

Methods: We have retrospectively screened our DXA studies from 2005 through 2010 and talked to patients as well as to care providers for the results and contents of X-ray study reports.

Results: A number of 5463 subjects received DXA studies between 2005 and 2010 at our department and 1081 were suggested to undergo a conventional X-ray of the lumbar spine (18.3%). In 53.6% of cases (n = 579), such an X-ray study had been performed. In this cohort, 25.2% had indeed a vertebral fracture while in 49.9, degenerative vertebral disease was present. In the remaining 24.9%, there were no pathological findings on conventional X-ray.

Conclusion: Even though the number of patients with degenerative disease exceeded that with fractures, our algorithm identified after all fractures in 25% of subjects with implausible high BMD scores. Therefore, BMD deviations of more than 10% of a vertebral body in comparison to adjacent vertebrae or a visibly smaller vertebral body size should be followed by conventional X-ray studies.