Analysis of Lumbar Spine and Hip Motion During Forward Bending in Subjects With and Without a History of Low Back Pain

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Abstract
This study analyzed two groups of subjects during forward bending. Group 1 (n = 20) contained subjects with a history of low back pain and Group 2 (n = 21) included subjects without a history of low back pain. The purposes of this study were to establish the amount and pattern of lumbar spine and hip motion during forward bending, and determine differences in motion in subjects with and without a history of low back pain. Reported values for lumbar spine motion during forward bending vary from 23.9 degrees to 60 degrees and hip motion during forward bending ranges from 26 degrees to 66 degrees. There has been no direct study of both lumbar spine and hip motion during forward bending in subjects with and without a history of low back pain to establish differences in total amounts or pattern of lumbar spine and hip motion during forward bending. A three-dimensional optoelectric motion analysis system was used 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. Hamstring flexibility was also assessed by two clinical tests, the passive straight leg raising and active knee extension tests. Mean total 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 differences for total amounts of lumbar spine and hip motion or velocity during forward bending. The pattern of motion was described by calculating lumbar-to-hip flexion ratios for early (0-30 degrees), middle (30-60 degrees), and late (60-90 degrees) forward bending. For all subjects, mean lumbar-to-hip ratios for early, middle, and late forward bending were 1.9, 0.9, and 0.4, respectively. Therefore, the lumbar spine had a greater contribution to early forward bending, the lumbar spine 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 bending and had a significantly lower lumbar-to-hip flexion ratio during middle forward bending (P < 0.01). Hamstring flexibility was strongly correlated to motion in subjects with a history of low back pain, but not in healthy subjects. The results provide quantitative data to guide clinical assessment of forward bending motion. Results also suggest that although people with a history of low back pain have amounts of lumbar spine and hip motion during forward bending similar to those of healthy subjects, the pattern of motion is different. It may be desirable to teach patients with a history of low back pain to use more hip motion during early forward bending, and hamstring stretching may be helpful for encouraging earlier hip motion.