Bone mass in ankylosing spondylitis

E. Toussirot, D. Wendling

Department of Rheumatology, University Hospital J. Minjoz, Besançon Cédex, France. 

ABSTRACT
Specific spine ossifications or syndesmophytes are considered to be a hallmark of ankylosing spondylitis (AS) and to reflect a process of bone formation. Conversely, AS patients may develop osteoporosis (OP), as suggested by radiographic studies, an increased frequency of the vertebral fracture rate and reduced bone mass. Dual energy X-ray absorptiometry measurements have clearly demonstrated decreased bone mineral density (BMD) at both the lumbar spine and femoral neck. However, for patients with advanced spinal changes, ossifications may yield normal or increased values for the lumbar spine BMD. Assessment of biochemical markers of bone metabolism have shown that both bone formation and resorption are involved, with enhanced urinary excretion of markers of collagen breakdown in patients with active disease and raised inflammatory parameters, and changes in the levels of some bone growth factors. The pathophysiology of this osteoporosis in AS mainly involves disease activity and, very likely, inflammatory cytokines. Finally, vertebral fractures complicating this bone loss contribute to spine deformity in patients with AS. 

Key words
Bone mineral density, ankylosing spondylitis, DEXA, fractures.

Please address correspondence and reprint request to: Eric Toussirot, MD, PhD Department of Rheumatology, University Hospital J. Minjoz, Boulevard A. Fleming, F-25030 Besançon Cédex, France.  
E-mail: eric.toussirot@ufc-chu.univ-fcomte.fr

Clin Exp Rheumatol 2000; 18 (Suppl. 21): S16-S20.
© Copyright Clinical and Experimental Rheumatology 2000.