The association between pain-related psychological variables and postural control in low back pain: A systematic review and meta-analysis.

BACKGROUND: Alterations in postural control have been found in individuals with low back pain (LBP), particularly during challenging postural tasks. Moreover, higher levels of negative pain-related psychological variables are associated with increased trunk muscle activity, reduced spinal movement, and worse maximal physical performance in individuals with LBP. RESEARCH QUESTION: Are pain-related psychological variables associated with postural control during static bipedal standing tasks in individuals with LBP? METHODS: A systematic review and meta-analysis were conducted. Pubmed, Web of Science, and PsycINFO were searched until March 2023. Studies were included if they evaluated postural control during static bipedal standing in individuals with LBP by measuring center of pressure (CoP) variables, and reported at least one pain-related psychological variable. Correlation coefficients between pain-related psychological variables and CoP variables were extracted. Study quality was assessed with the "Quality In Prognosis Studies" tool (QUIPS). Random-effect models were used to calculate pooled correlation coefficients for different postural tasks. Sub-analyses were performed for positional or dynamic CoP variables. Certainty of evidence was assessed with an adjusted "Grading of Recommendations, Assessment, Development, and Evaluations" tool (GRADE). The protocol was registered on PROSPERO (CRD42021241739). RESULTS: Sixteen studies (n = 723 participants) were included. Pain-related fear (16 studies) and pain catastrophizing (three studies) were the only reported pain-related psychological variables. Both pain-related fear (-0.04 < pooled r < 0.14) and pain catastrophizing (0.28 < pooled r < 0.29) were weakly associated with CoP variables during different postural tasks. For all associations, the certainty of evidence was very low. SIGNIFICANCE: Pain-related fear and pain catastrophizing are only weakly associated with postural control during static bipedal standing in individuals with LBP, regardless of postural task difficulty. Certainty of evidence is very low thus it is conceivable that future studies accounting for current study limitations might reveal different findings.

Rehabilitation to improve outcomes of lumbar fusion surgery: a systematic review with meta-analysis.

PURPOSE: To evaluate the effectiveness of rehabilitation strategies on disability, pain, pain-related fear, and return-to-work in patients undergoing lumbar fusion surgery for degenerative conditions or adult isthmic spondylolisthesis. METHODS: Six electronic databases were systematically searched for randomized controlled trials (RCTs) evaluating the effect of rehabilitation (unimodal or multimodal). The estimated effect size was calculated for interventions with homogeneous content using a random-effects model. Certainty of evidence was assessed by GRADE. RESULTS: In total, 18 RCTs, including 1402 unique patients, compared specific rehabilitation to other rehabilitation strategies or usual care. Most described indications were degenerative disc disease and spondylolisthesis. All rehabilitation interventions were delivered in the postoperative period, and six of them also included a preoperative component. Intervention dose and intensity varied between studies (ranging from one session to daily sessions for one month). Usual care consisted mostly of information and postoperative mobilization. At short term, low quality of evidence shows that exercise therapy was more effective for reducing disability and pain than usual care (standardized mean difference [95% CI]: -0.41 [-0.71; -0.10] and -0.36 [-0.65; -0.08], four and five studies, respectively). Multimodal rehabilitation consisted mostly of exercise therapy combined with cognitive behavioral training, and was more effective in reducing disability and pain-related fear than exercise therapy alone (-0.31 [-0.49; -0.13] and -0.64 [-1.11; -0.17], six and four studies, respectively). Effects disappeared beyond one year. Rehabilitation showed a positive tendency towards a higher return-to-work rate (pooled relative risk [95% CI]: 1.30 [0.99; 1.69], four studies). CONCLUSION: There is low-quality evidence showing that both exercise therapy and multimodal rehabilitation are effective for improving outcomes up to six months after lumbar fusion, with multimodal rehabilitation providing additional benefits over exercise alone in reducing disability and pain-related fear. Additional high-quality studies are needed to demonstrate the effectiveness of rehabilitation strategies in the long term and for work-related outcomes.

Influence of phase of respiratory cycle on ultrasound imaging of deep abdominal muscle thickness.

BACKGROUND: It is difficult to evaluate the transversus abdominis (TrA) and internal oblique (IO) due to their dual role in both trunk control and breathing. OBJECTIVES: To investigate whether TrA and IO thickness as measured by ultrasound differs across the respiratory cycle in upright standing. DESIGN: Observational study. METHODS: Thickness of TrA and IO was measured with ultrasound in 67 subjects in upright standing. Measures were performed 3 times and by 2 assessors, at the end of relaxed expiration, at the end of a full inspiration, and at the end of full expiration. Differences were assessed by ANOVA. Intra- and inter-rater reliability (of a single measure and the average of 3 measures) were assessed by intra-class correlation (ICC). RESULTS: Thickness of the TrA and IO was higher at full expiration than at the end of relaxed expiration (p < 0.001), and in turn compared to at full inspiration (p < 0.001). Intra-rater reliability was excellent at all respiratory phases (ICC 0.76-0.87). Whereas inter-rater reliability for a single measure was only fair to good for TrA (ICC 0.52-0.71) and good to excellent for IO (ICC 0.61-0.78), the inter-rater reliability of the average was excellent at all respiratory phases (ICC 0.75-0.90). CONCLUSIONS: Thickness of TrA and IO increases when lung volume decreases. The intra- and inter-rater reliability of an average measure were excellent at the end of relaxed expiration, full inspiration and full expiration. This provides new opportunities to evaluate the deep abdominal muscles, and their role in respiration, in a physiotherapeutic setting.