Dynamic multi-segmental postural control in patients with chronic non-specific low back pain compared to pain-free controls: A cross-sectional study

PLoS One. 2018 Apr 10;13(4):e0194512. doi: 10.1371/journal.pone.0194512. eCollection 2018.

Abstract

Reduced postural control is thought to contribute to the development and persistence of chronic non-specific low back pain (CNLBP). It is therefore frequently assessed in affected patients and commonly reported as the average amount of postural sway while standing upright under a variety of sensory conditions. These averaged linear outcomes, such as mean centre of pressure (CP) displacement or mean CP surface areas, may not reflect the true postural status. Adding nonlinear outcomes and multi-segmental kinematic analysis has been reported to better reflect the complexity of postural control and may detect subtler postural differences. In this cross-sectional study, a combination of linear and nonlinear postural parameters were assessed in patients with CNLBP (n = 24, 24-75 years, 9 females) and compared to symptom-free controls (CG, n = 34, 22-67 years, 11 females). Primary outcome was postural control measured by variance of joint configurations (uncontrolled manifold index, UI), confidence ellipse surface areas (CEA) and approximate entropy (ApEn) of CP dispersion during the response phase of a perturbed postural control task on a swaying platform. Secondary outcomes were segment excursions and clinical outcome correlates for pain and function. Non-parametric tests for group comparison with P-adjustment for multiple comparisons were conducted. Principal component analysis was applied to identify patterns of segmental contribution in both groups. CNLBP and CG performed similarly with respect to the primary outcomes. Comparison of joint kinematics revealed significant differences of hip (P < .001) and neck (P < .025) angular excursion, representing medium to large group effects (r's = .36 - .51). Significant (P's < .05), but moderate correlations of ApEn (r = -.42) and UI (r = -.46) with the health-related outcomes were observed. These findings lend further support to the notion that averaged linear outcomes do not suffice to describe subtle postural differences in CNLBP patients with low to moderate pain status.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Biomechanical Phenomena
  • Chronic Pain / therapy*
  • Cross-Sectional Studies
  • Female
  • Humans
  • Low Back Pain / therapy*
  • Male
  • Middle Aged
  • Movement
  • Multivariate Analysis
  • Pain Management
  • Postural Balance / physiology
  • Posture / physiology*
  • Treatment Outcome
  • Young Adult

Grants and funding

MM and CS were partially funded by a grant from the cantonal department of health and social services of the Canton of Argovia (www.ag.ch/dgs), Switzerland. Internal funding was provided by MM and CS’ employer, Reha Rheinfelden, Switzerland. BW and EdB were funded by their employers, ETH Zurich, as part of their teaching activity (PhD supervision). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript and the authors had unrestricted access to the data. There was no additional external funding received for this study.