Relationships between Lumbar Intervertebral Disc Degeneration and Muscle Volumes of the Extremities and Trunk in the Elderly

Abstract

The purpose of this study is to investigate the relationships between lumbar intervertebral disc degeneration and muscle volumes of the extremities and trunk and between disc degeneration and lumbosacral spinal alignment in elderly people in Japan.The subjects were 222 adults who were participating in a health promotion exercise program (82 males and 140 females; mean age, 70.0 years; range, 60-86 years). Disc degeneration, lumbar lordotic angle and sacral inclination angle were evaluated using T2-weighted lumbar sagittal MR images. The thicknesses of the back and abdominal muscles were determined by ultrasonography, and the humeral, forearm, femoral and crural muscle volumes were estimated from the associated muscle thicknesses examined through ultrasonography. The transversal area of the psoas major muscle was also measured with MR images.Findings determined by a logistic regression analysis adjusted for age and gender, show a decrease of the anterior muscle volume of the femur was statistically significantly associated with disc degeneration (odds ratio=0.80). The lumbar lordotic angle and sacral inclination angle were significantly small in the disc degeneration group. These results suggest that disc degeneration may be associated with the anterior muscle volume of the femur and lumbosacral spinal alignment in the elderly. We suspect that disc degeneration causes a decrease in the lumbar lordotic angle and also a compensatory decrease in the sacral inclination angle.