THE EFFECT OF CHRONIC LOW BACK PAIN ON THE SIZE AND ACTIVATION OF THE LUMBAR MULTIFIDUS MUSCLE

Wallwork, Tracy Leigh (2006). THE EFFECT OF CHRONIC LOW BACK PAIN ON THE SIZE AND ACTIVATION OF THE LUMBAR MULTIFIDUS MUSCLE MPhil Thesis, School of Health and Rehabilitation Sciences, University of Queensland.

       
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Author Wallwork, Tracy Leigh
Thesis Title THE EFFECT OF CHRONIC LOW BACK PAIN ON THE SIZE AND ACTIVATION OF THE LUMBAR MULTIFIDUS MUSCLE
School, Centre or Institute School of Health and Rehabilitation Sciences
Institution University of Queensland
Publication date 2006
Thesis type MPhil Thesis
Supervisor Dr Julie Hides
Subjects 329999 Medical and Health Sciences not elsewhere classified
Abstract/Summary The lack of control of lumbar stability is thought to be a major factor in the aetiology and chronicity of low back pain. The lumbar multifidus muscle is considered to play a significant role in maintaining lumbar stability and stiffness. The aim of this study was to use clinical measures to compare lumbar multifidus muscle in chronic low back pain patients and unimpaired subjects. Sixteen subjects with chronic low back pain and 16 unimpaired subjects were assessed in the study. Cross-sectional area (CSA) and contraction size of multifidus were measured on both sides and at individual vertebral levels, from L2 – L5, using realtime ultrasound. The differences between the chronic back pain and unimpaired groups were statistically significant for both cross-sectional area and contraction size measures. In the unimpaired group, the contraction size of multifidus was greatest at the L5 segmental level, and then decreased in size at higher lumbar levels. In the chronic low back pain group, the contraction size was the same at L4 and L5 levels and contractions were less at these levels than those at L2 and L3. Three way interactions showed a significant interaction (p<0.05) between vertebral levels, change in thickness and group. Contrasts revealed a significant difference (p<0.05) between upper lumbar levels (L2 and L3) and lower lumbar levels (L4 and L5) across groups. In the unimpaired group, the contraction size of multifidus was greater at lower lumbar levels (L4 and L5) than upper lumbar levels (L2 and L3), while in the low back pain group, the contraction size was less at lower lumbar levels than upper lumbar levels. A similar pattern occurred with multifidus CSA’s. In the unimpaired group, CSA was greatest at L5 and gradually reduced at higher lumbar levels. In the chronic back pain group, CSA’s were the same at L5 and L4 and only slightly greater than L3. Two way interactions showed a highly significant difference (p<0.01) between groups across vertebral levels. There was a significant difference between upper lumbar levels (L2and L3) and lower lumbar levels (L4 and L5). Lower lumbar levels were less in the chronic low back pain group than the unimpaired group, when compared to upper lumbar levels. Estimated marginal means showed that CSA at L5 was significantly less in the chronic low back pain group (confidence interval >95%). Results of the study indicate that chronic low back pain patients have poorer muscle activation and greater muscle wasting of multifidus muscle at the lower lumbar levels compared with higher lumbar levels, than normal subjects. Clinical programmes should aim to restore multifidus muscle activation and size, in patients with chronic low back pain.

 
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Created: Fri, 21 Nov 2008, 15:02:02 EST