Article

Minimal longitudinal data exist regarding the role of lumbar
musculature in predicting back pain and function. In cross-sectional study
designs, there is often atrophy of the segmental multifidus muscle in subjects
with low back pain compared with matched controls. However, the cross-sectional
design of these studies prevents drawing conclusions regarding whether lumbar
muscle characteristics predict or modify future back pain or function.
The primary objective of this study is to determine whether the cross-sectional
area (CSA) of lumbar muscles predict functional status or back pain at 6- or
12-month follow-up in older adults with spinal degeneration. The secondary
objective is to evaluate whether these muscle characteristics improve outcome
prediction above and beyond the prognostic information conferred by demographic
and psychosocial variables. DESIGN: Secondary analysis of a randomized controlled
trial. PARTICIPANTS: A total of 209 adults aged 50 years and older with clinical
and radiographic spinal stenosis from the Lumbar Epidural steroid injection for
Spinal Stenosis (LESS) trial. METHODS: Using baseline magnetic resonance images,
we calculated CSAs of the lumbar multifidus, psoas, and quadratus lumborum
muscles using a standardized protocol by manually tracing the borders of each of
the muscles. The relationship between lumbar muscle CSAs and baseline measures
was assessed with Pearson or Spearman correlation coefficients. The relationship
between lumbar muscle characteristics and 6- and 12-month Roland Morris
Disability Questionnaire (RDQ) and back pain Numeric Rating Scale (NRS) responses
was further evaluated with multivariate linear regression. A hierarchical
approach to the regression was performed: a basic model with factors of
conceptual importance including age, gender, BMI, and baseline RDQ score formed
the first step. The second and third steps evaluated whether psychosocial
variables or muscle measures conferred additional prognostic information to the
basic model. MAIN OUTCOME MEASURES: Function as measured by the RDQ and back pain
as measured by the NRS at 6- and 12-month follow-up. RESULTS: Lumbar muscle CSA
was not a significant predictor of 6- or 12-month RDQ or pain score in
multivariate analyses. CONCLUSIONS: Cross-sectional areas of lumbar muscles do
not predict function or pain at medium- and long-term follow-up in adults with
lumbar spinal stenosis. LEVEL OF EVIDENCE: III.
CI - Copyright (c) 2017 American Academy of Physical Medicine and Rehabilitation.
Published by Elsevier Inc. All rights reserved.

Langue : ANGLAIS