INFLUENCE OF OSTEOPHYTIC SIZE ON BONE-MINERAL DENSITY MEASURED BY DUAL X-RAY ABSORPTIOMETRY

Purpose: To quantify the relationship between individual osteophytic s ize and measured bone mineral density (BMD) of the lumbar spine by dua l x-ray absorptiometry (DXA). Further, to evaluate the possible conseq uences of this relationship for the management of DXA measurements in postmenopausal patients. Material and Methods: In 142 postmenopausal w omen (mean age 61.8+/-8.9 years), plain radiographs of the lumbar spin e were evaluated and graded according to evidence and size of osteophy tes. The BMD (g/cm(2)) and Z-score (deviation of BMD from an age-match ed population, %) of each vertebral body was determined by DXA. The ef fects of the individual osteophytic size on BMD measurements were anal yzed by using analysis of variance followed by a multiple test procedu re Results: The presence of osteophytes resulted in a significant incr ease in BMD of L1 through L4. The increase in relation to an osteophyt ic size of about 10 mm was: in L1 5.7%, in L2 6.8%, in L3 4.4% and in L4 3.5%. Increases were significantly higher for an osteophytic size o f 10-20 mm (L1 23.1%, L2 13.0%, L3 13.4%, and L4 16.3%) and of >20 mm (L1 21.4%, L2 22.4%, L3 21.1% and L4 3.1%).Conclusion: Our results ind icate a nonlinear increase of measured BMD with increasing osteophytic size. These effects should be considered in routine examination and p atient management.