Background Patients with ankylosing spondylitis are well-known to have an increased incidence of osteoporosis/osteopenia. Consequently, control measurements of bone densitometry should be done more frequently than in the normal population. Ultrasound densitometry has the advantage to be free of radiation and having been used widely. However, DXA is still a “gold standard”.
Objectives The aim of our study was to look at the relationship of the ultrasound densitometry and DXA-measurements in patients with ankylosing spondylitis.
Methods We have examined 184 patients with ankylosing spondylitis. All patients fulfilled the modified New York criteria. We measured the bone mineral density of the right hip and lumbar spine with DXA (QDR 4500) and of the calcaneus with ultrasound (UBIS 5000).
Results The best correlation was found between DXA of the right hip and ultrasound of the calcaneus.
The correlation of BMD hip total with ultrasound BUA was r = 0.235(p < 0.001, with ultrasound T-Score r = 0,205 (P < 0,005) and with ultrasound Z-Score r = 0.203 (p < 0,006). The corresponding correlations of BMD of the lumbar spine with ultrasound BUA (r = 0,135 P = 0,067) were not significant.
Conclusion The hip total measured by DXA present with significant (p > 0,005) correlations with ultrasound measurements of the calcaneus.
In contrast, BMD of the lumbar spine did not show significant correlations with the ultrasound measurements. As measurements of BMD of the lumbar spine in patients with ankylosing spondylitis have limitations due to disease specific changes of the lumbar vertebra, ultrasound of the calcaneus measurement should be considered as an alternative, too.