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

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.

The Difference of Bone Mineral Density of Lumbar Spine and Wrist in the Preterm and Full-term Infants: Using Dual Energy X-ray Absorptiometry

PURPOSE: To assess the differences in bone mineral density (BMD) of lumbar spine and wrist between preterm infants of postconceptional age 40 weeks and normal full-term infants. MATERIALS AND METHODS: Sixty-eight preterm infants born at conceptional age 26 -36 weeks and 31 normal full-term infants born at 38 -42 weeks were investigated. Bone mineral densities of the lumbar spine (from the second to the fourth segment) and wrist were measured by dual energy X-ray absorptiometry. In preterm infants, the corrected age of 0 month was defined as postconceptional 40 weeks. Full-term infants were evaluated within three days of birth, and the average bone mineral densities of preterm and full-term infants were compared. In the preterm group, birth weight and conceptional age were correlated with lumbar spinal and wrist bone mineral densities. Data were analyzed by student's t-test and Pearson's correlation coefficient, and a pvalue of less than 0.05 was considered significant. RESULTS: In preterm in fants, the values of bone mineral densities of the lumbar spine and wrist were 0.137 +/- 0.018 g/cm2(0.061 -0.202 g/cm2) and 0.089 +/-0.013 g/cm2 (0.065 -0.123 g/cm2), respectively, while the respective values for full-term infants were 0.214 +/-0.030 g/cm2 (0.160 -0.296 g/cm2) and 0.118 +/-0.014 g/cm2(0.096 -0.162 g/cm 2). In the preterm group, lumbar spinal BMD correlated significantly with conceptional age(r=0.384, p0.05). CONCLUSION: The lumbar spinal and wrist BMDs of preterm infants at corrected age 0 were lower than those of normal full-term infants. In the preterm group, BMD values for the lumbar spine were lower in infants of lower conceptional age and birth weight.

Quantitative Morphologic Assessment of Thoracolumbar Vertebrae in Korean Women by Morphometric X-rayAbsorptiometry

PURPOSE: To compare the accuracy of lateral radiography of the spine with that of morphometric X-rayabsorptiometry(MXA) in vertebral morphometry, and to evaluate normal vertebral morphometry using MXA in Koreanwomen. MATERIALS AND METHODS: A spine phantom was constructed using copper pipe. Its anterior and posteriorheights were measured directly, with lateral radiographs and with MXA, and the values thus obtained were compared.Inter -and intra -observer variations were evaluated by three radiologists. The vertebral morphometry of 30 youngwomen volunteers were imaged using thoracic and lumbar lateral radiographs and MXA, and analysis included themeasurement of anterior and posterior heights from T4 to L4. We also obtained the vertebral morphometry of 200normal Korean women who underwent MXA between March 1995 and February 1996, though those with osteoporosis andother spinal lesions were excluded from this study. Thoracolumbar vertebral indexes were statistically correlatedwith age, height and bone mineral. RESULTS: There were no statistically significant differences in the heights ofspine phantom measured by MXA compared with actual size (mean difference=0.28mm). Simple radiographs weremagnified by 23.7% at a phantom-table distance of 15cm, and distortion ranged from 0.5% to 22.5%, depending onphantom level and phantom-table distance. In the study of volunteers, the magnification rate between a simpleradiograph and MXA was about 26.6%. Anterior height increased progressively from the thoracic to the lumbar spine,though posterior height peaked at L2, and L4 was less than anterior height. In Korean women, indices of vertebralmorphometry decreased significantly with aging, with the most prominent decrease occurring during the seventhdecade. The mineral density of spinal bone decreased markedly after the sixth decade. CONCLUSION: Radiographsshowed more magnification and distortion than did MXA, though between morphometric X-ray absorptiometry (MXA) andactual size, there was no significant difference. The vertebral morphometric indices of Korean women and referredbone mineral density may provide useful data for determining and evaluating follow-up changes in spinalmorphology.

The Usefulness of Whole Body Bone Mineral Densitometry in the Osteopenia of Preterm Infants: Comparison with the Wrist Radiography and Biochemical Parameters

PURPOSE: To evaluate the usefulness of whole body bone mineral densitometry in the diagnosis of frequent osteopenia of preterm infants by comparison with the wrist radiographs and biochemical parameters. MATERIALS AND METHODS: From January 1995 to January 1996, we obtained whole body bone mineral density(BMD) studies using dual energy X-ray absorptiometry(DXA) and wrist radiographs of 39 preterm infants. They were divided into three groups according to birth weight, under 1500g, 1501g to 2000g and above 2000g, and four grades of skeletal change, as seen on wrist radiography, according to the scoring method of Koo et al. Groups of birth weight and grades of skeletal change were then correlated with whole body BMD and biochemical parameters. For comparison, normal data were obtained from 13 infants born at full term. Data were analyzed by one way analysis of variation(ANOVA) and correlation and regression analysis. A p-value of less than 0.05 was considered significant. RESUTLS: Whole body BMDs were significantly lower in the more premature and smaller birth weight infants(r=0.77, p=0.0000), and in the higher grade of skeletal change (r=-0.5276, p=0.0000). Aggravated skeletal changes were found in infants with lower birth weight(r=-0.3822, p=0.01). Interobserver variation in grading skeletal change was 42.9%, and intraobserver variation was 18.4%. Biochemical parameters such as serum calcium, phosphate, alkaline phosphatase, parathromone, calcitonin and 25-hydroxy-vitamine D did not vary significantly according to either birth weight or skeletal change (p>0.05). CONCLUSION: Premature osteopenia is more effectively diagnosed by measuring whole body BMD using DXA than by grading radiographical skeletal change or by biochemical parameters.