Lumbar Spine Degenerative Disease: Effect on Bone Mineral Density Measurements in the Lumbar Spine and Femoral Neck

ABSTRACT

PURPOSE: To determine the effect of degenerative disease of the lumbar spine on bone mineral density in the lumbar spine and femoral neck. MATERIALS AND METHODS: We reviewed radiographs and dual energy x-ray absorptiometry scans of the lumbar spine and hip in 305 Caucasian women with suspected osteoporosis. One hundred and eighty-six patients remained after excluding women less than 40 years of age (n = 18) and those with hip osteoarthritis, scoliosis, lumbar spine fractures, lumbar spinal instrumentation, hip arthroplasty, metabolic bone disease other than osteoporosis, or medications known to influence bone metabolism (n = 101). On the basis of lumbar spine radiographs, those with absent/mild degenerative disease were assigned to the control group and those with moderate/severe degenerative disease to the degenerative group. Spine radiographs were evaluated for degenerative disease by two radiologists working independently; discrepant evaluations were resolved by consensus. Lumbar spine and femoral neck bone mineral density was compared between the two groups. RESULTS: Forty-five (24%) of 186 women were assigned to the degenerative group and 141 (76%) to the control group. In the degenerative group, mean bone mineral density measured 1.075 g/cm in the spine and 0.788 g/cm in the femoral neck, while for controls the corresponding figures were 0.989 g/cm and 0.765 g/cm Adjusted for age, weight and height by means of analysis of variance, degenerative disease of the lumbar spine was a significant predictor of increased bone mineral density in the spine (p = 0.0001) and femoral neck (p = 0.0287). CONCLUSION: Our results indicate a positive relationship between degenerative disease of the lumbar spine and bone mineral density in the lumbar spine and femoral neck, and suggest that degenerative disease in that region, which leads to an intrinsic increase in bone mineral density in the femoral neck, may be a good negative predictor of osteoporotic hip fractures.