Bone mineral density of visually handicapped women

While physical activity is an essential factor for muscle performance and development and also for the maintenance of bone mass in the loaded bones, apparently low intensity of physical activity of blind persons may compromise the muscle performance and bone mineral density (BMD). Therefore, the aim was to study whether there are differences in BMD of the weight-bearing or non-weight-bearing bones between visually handicapped persons and those with normal sight. Nineteen visually handicapped premenopausal women and their matched pairs were recruited to the study. The mean age of the visually handicapped women was 39.9 years (SD 8.1) and that of the women with normal vision 39.7 years (6.5). BMD of the distal radius, femoral neck and trochanter was measured with dual energy X-ray absorptiometry (DXA), and isometric muscle strength of the extremities and trunk with a dynamometer. Between-group differences were compared with paired Student's t-test. The BMD at the femur was 8% higher in favour of the group with normal sight, whereas radial BMD was similar in the two groups. The t-score was -1.0 (95% confidence interval -1.5 to -0.5) for the femoral neck BMD and -0.7 (-1.1 to -0.2) for the trochanter BMD in the group with impaired vision. The respective t-scores for the group with normal sight were -0.3 (-0.9 to 0.3) for the femoral neck and 0 (-0.7 to 0.7) for the trochanter. Visual handicap seems to be a risk for lower BMD of the weight-bearing proximal femur, but not for lower BMD of the non-weight-bearing distal radius.