Factors related to spinal mobility in patients with postmenopausal osteoporosis.

Quality of life in patients with spinal osteoporosis is impaired by the decline of spinal mobility. However, the factors related to the spinal mobility in these patients are still unclear. We evaluated the possible factors affecting spinal mobility in patients with postmenopausal osteoporosis. A total of 128 postmenopausal women with osteoporosis aged over 50 years (mean, 70 years) were included in this study. The thoracic and lumbar kyphosis angles and range of motion (ROM) of the total spine were measured in the upright position and at maximum flexion/extension with a computer-assisted device. The paravertebral muscle thicknesses (PVMT) of thoracic and lumbar spine in the upright position were measured using an ultrasound unit. The number of vertebral fractures was evaluated with radiographs of the spine. Isometric back extensor strength (BES) was evaluated with a strain-gauge dynamometer. Correlations between these variables were then analyzed. Age (r=-0.412), lumbar kyphosis angle (r=-0.284), BES (r=0.369), PVMT at the lumbar spine (r=0.227) and the number of vertebral fractures (r=-0.260) showed significant correlations with total spinal ROM (P<0.05). However, no significant correlations were observed between the total spinal ROM and PVMT at the thoracic spine (r=-0.069) or thoracic kyphosis angle (r=-0.138). Multiple regression analysis revealed that the BES was the most significant contributor to the total spinal ROM. The present study suggests a possible association between BES and spinal mobility in patients with postmenopausal osteoporosis.