Radiographic features of lumbar disc degeneration and bone mineral density in men and women

Objectives: To determine the association between individual radiographic features of lumbar disc degeneration and bone mineral density (BMD) at the spine and hip. Methods: Subjects were recruited from a population register for a screening survey of vertebral osteoporosis. BMD was assessed at the spine and hip using dual energy x ray absorptiometry. Lateral spinal radiographs were evaluated for features of lumbar disc degeneration. Each vertebral level from L1/2 to L4/5 was assessed for the presence and severity of osteophytes, end plate sclerosis, and disc space narrowing. Linear regression was used to determine the association between each of these features and BMD at the spine and hip, with adjustments for age, body mass index, and levels of physical activity. Analyses were done separately in men and women. Results: 250 women and 256 men ( mean age around 65 years) were studied. At the lumbar spine, after age adjustment there was an increase in BMD with increasing grade for all radiographic features of disc degeneration in both men and women. At the femoral neck, after age adjustment there was an increase in BMD with increasing osteophyte and end plate sclerosis grade though not disc space narrowing. Adjusting for body mass index and physical activity did not influence the strength of the associations. Conclusions: Radiographic features of lumbar disc degeneration are associated with an increase in BMD at the spine. Osteophytes and end plate sclerosis, but not disc space narrowing, are associated with an increase in BMD at the hip.