ANALYSIS OF LUMBAR SPINE AND HIP MOTION DURING FORWARD BENDING IN SUBJECTS WITH AND WITHOUT A HISTORY OF LOW-BACK-PAIN

Study Design. This study analyzed two groups of subjects during forwar d bending. Group 1 (n = 20) contained subjects with a history of low b ack pain and Group 2 (n = 21) included subjects without a history of l ow back pain. Objective. The purposes of this study were to establish the amount and pattern of lumbar spine and hip motion during forward b ending, and determine differences in motion in subjects with and witho ut a history of low back pain. Summary of Background Data. Reported va lues for lumbar spine motion during forward bending vary from 23.9 deg rees to 60 degrees and hip-notion during forward bending ranges from 2 6 degrees to 66 degrees. There has been no direct study of both lumbar spine and hip motion during forward bending in subjects with and with out a history of low back pain to establish differences in total a mou nts or pattern of lumbar Spine and hip motion during forward bending. Methods. A three-dimensional optoelectric motion analysis system was u sed to measure the amount and velocity of lumbar spine and hip motion during forward bending, Each subject performed three trials of forward bending that were averaged and used for statistical analysis. Hamstri ng flexibility was also assessed by two clinical tests, the passive st raight leg raising and active knee extension tests. Results. Mean tota l forward bending for all subjects was 111 degrees: 41.6 degrees from the lumbar spine and 69.4 degrees from the hips. There were no group d ifferences for total amounts of lumbar spine and hip motion or velocit y during forward bending. The pattern of motion was described by calcu lating lumbar-to-hip flexion ratios for early (0-30 degrees), middle ( 30-60 degrees), and late (60-90 degrees) forward bending. For all subj ects, mean lumbar-to-hip ratios for early, middle, and late forward be nding were 1.9, 0.9, and 0.4, respectivelyl. Therefore, the lumbar spi ne had a greater contribution to early forward bending, the lumbar spi ne and hips contributed almost equally to middle forward bending, and the hips had a greater contribution to late forward bending. A t test revealed a difference between groups for the pattern of motion. Group 1 tended to move more at their lumbar spine during early forward bendi ng and had a significantly lower lumbar-to-hip flexion ratio during mi ddle forward bending (P < 0.01). Hamstring flexibility was strongly co rrelated to motion in subjects with a history of low back pain, but no t in healthy subjects. Conclusions. The results provide quantitative d ata to guide clinical assessment of forward bending motion. Results al so suggest that although people with a history of low back pain have a mounts of lumbar spine and hip motion during forward bending similar t o those of healthy subjects, the pattern of motion is different. It ma y be desirable to teach patients with a history of low back-pain to us e more hip motion during early forward bending, and hamstring stretchi ng may be helpful for encouraging earlier hip motion.