Researchers in Japan are investigating the link between scoliosis (curvature of the spine) and osteoporosis (brittle bones). They reviewed the medical records of 176 adults who had surgery for scoliosis. All patients were women between the ages of 26 and 82.

The authors were interested in finding out if women with scoliosis were more likely to develop osteoporosis as a result of having the scoliosis. Other studies have suggested a link between osteoporosis and scoliosis. Does it go both ways?

There is some question about the ability of standard osteoporosis scanning devices to accurately measure bone mineral density in a curved spine. It's possible the readings may be falsely elevated (i.e., measurements record a higher bone mineral density than is actually present).

That's why this study was designed to look at two separate bone density measurements: one in the lumbar spine and the other at the femoral neck (area of bone between the shaft of the thigh bone and the round bone at the top of the thigh bone). Dual energy radiograph absorptiometry or DXA scans were used to measure and compare bone mineral density at both sites.

A second feature of this study was to see if osteoporosis in adult women with scoliosis affects the final results of surgery. Success of the fusion, number and type of complications, and final scoliosis curve were used as measures of surgical outcomes.

They found that the older women in the study were more likely to have decreased bone mineral density. The amount of bone loss was similar between hip and spine. And the amount of bone loss in adult women with scoliosis was pretty much the same (no statistical difference) as women the same age who did not have scoliosis.

The study also showed that severity of the spinal curve was NOT linked with bone loss. In other words, a more severe curve did not mean a greater risk of developing osteoporosis. And vice versa: bone loss did not increase the size of the spinal curve.

As far as the results of the spinal fusion surgery, the fusion rate was excellent (93 per cent). The complication rate was 13.6 per cent. There was not a statistically significant relationship between the presence of osteoporosis and number of complications.

The authors think that the results of this study may help prove that adult scoliosis does not occur as a result of osteoporosis in postmenopausal women. And along the same lines, the spinal curvature won't get worse if osteoporosis is present. It's more likely that advancing age is the main reason why scoliosis curves develop and/or get worse in older women.

They suggest that having osteoporosis will not prevent bone fusion after spinal surgery. The bottom-line is that women (especially older women who have gone through menopause) can have spinal fusion for scoliosis. The procedure is safe and unaffected by the weaker bone structure so common in this age group. Further study on a larger number of patients including men is needed.

Reference: Mitsuru Yagi, MD, PhD, et al. Characterization of Osteopenia/Osteoporosis in Adult Scoliosis. In Spine. September 15, 2011. Vol. 36. No. 20. Pp. 1652-1657.