Effect of Osteoporosis on Morphology and Mobility of the Lumbar Spine

Study Design. Cross-sectional study. Objective. The purpose of this study was to examine disc morphology and spinal mobility in subjects with varying degrees of osteoporosis. Summary of Background Data. There was limited information on the effect of osteoporosis on lumbar morphology and spinal mobility. It was also unclear how osteoporosis affects the nonosseous tissues such as the intervertebral disc. Methods. Ninety elderly subjects with varying bone mineral densities (22 normal, 28 osteopenia, 40 osteoporosis) were recruited from an osteoporosis clinic. Lateral radiographs and magnetic resonance images of their lumbar spines were obtained. An electromagnetic tracking device was employed to measure the ranges of motion of the whole lumbar spine. Results. Although the thoracic spine had been shown to have decreased anterior vertebral body height in subjects with osteoporosis, this study revealed that the anterior height was increased in the lumbar region. Osteoporosis was associated with expansion of the middle of the disc with corresponding collapse of vertebral bodies, but osteoporosis was found not to be related to either disc preservation or degeneration. No significant change in spinal mobility was observed in patients with osteoporosis. Conclusion. Osteoporosis does not only affect the bone but also the nonosseous tissues. It was found to be associated with expansion of the intervertebral disc, which was likely to be secondary to changes in the vertebral endplate.