Department of Health Sciences and Technology, Institute for Human Movement Sciences, ETH Zurich, Zurich, Switzerland.
Research Department, Reha Rheinfelden, Rheinfelden, Switzerland.
PLoS One. 2018 Apr 10;13(4):e0194512. doi: 10.1371/journal.pone.0194512. eCollection 2018.
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.
姿势控制能力下降被认为是导致慢性非特异性下腰痛（CNLBP）发展和持续存在的原因之一。因此，在受影响的患者中经常对其进行评估，并通常报告为在各种感觉条件下直立站立时的姿势摆动平均量。这些平均线性结果，例如平均中心压力（CP）位移或平均 CP 表面积，可能无法反映真实的姿势状态。据报道，增加非线性结果和多节段运动学分析可以更好地反映姿势控制的复杂性，并可能检测到更微妙的姿势差异。在这项横断面研究中，对 CNLBP 患者（n = 24，24-75 岁，9 名女性）和无症状对照组（CG，n = 34，22-67 岁，11 名女性）评估了线性和非线性姿势参数的组合。主要结果是通过关节配置的方差（未控制流形指数，UI）、CP 离散度的置信椭圆表面积（CEA）和近似熵（ApEn）测量的姿势控制，在摇摆平台上的扰动姿势控制任务的响应阶段。次要结果是节段偏移量和疼痛与功能的临床结果相关性。进行了用于组比较的非参数检验，并进行了 P 调整的多次比较调整。应用主成分分析识别两组中节段贡献的模式。CNLBP 和 CG 在主要结果方面表现相似。关节运动学的比较显示髋关节（P <.001）和颈部（P <.025）角度偏移的显著差异，代表中到大组效应（r's =.36 -.51）。观察到 ApEn（r = -.42）和 UI（r = -.46）与健康相关结果的显著（P <.05）但中等相关性。这些发现进一步支持这样的观点，即平均线性结果不足以描述具有低至中度疼痛状态的 CNLBP 患者的微妙姿势差异。
