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BackgroundInterventions for low back pain (LBP) commonly target ‘dysfunctional’ or atypical lumbo-pelvic kinematics in the belief that correcting aberrant movement improves patients’ pain and activity outcomes. If atypical kinematic parameters and postures have a relationship to LBP, they could be expected to more prevalent in people with LBP compared to people without LBP (NoLBP). This exploratory study measured, defined and compared atypical kinematic parameters in people with and without LBP.MethodsWireless inertial motion and EMG sensors were used to measure lumbo-pelvic kinematics during standing trunk flexion (range of motion (ROM), timing, sequence coordination, and extensor muscle activation) and in sitting (relative sitting position, pelvic tilt range) in a sample of 126 of adults without LBP and 140 chronic LBP subjects. Atypical movement was defined using the 10th/90th centiles of the NoLBP group. Mean differences and prevalence rates for atypical movement were calculated. Dichotomised pain scores for ‘high-pain-on-bending’ and ‘high-pain-on-sitting’ were tested for their association with atypical kinematic variables.ResultsFor standing flexion, significant mean differences, after adjusting for age and gender factors, were seen for the LBP group with (i) reduced ROM (trunk flexion (NoLBP 111o, LBP 93o, p < .0001), lumbar flexion (NoLBP 52o, LBP 46o, p < .0001), pelvic flexion (NoLBP 59o, LBP 48o, p < .0001), (ii) greater extensor muscle activation for the LBP group (NoLBP 0.012, LBP 0.25 p < .0001), (iii) a greater delay in pelvic motion at the onset of flexion (NoLBP − 0.21 s; LBP − 0.36 s, p = 0.023), (iv) and longer movement duration for the LBP group (NoLBP 2.28 s; LBP 3.18 s, p < .0001). Atypical movement was significantly more prevalent in the LBP group for small trunk (× 5.4), lumbar (× 3.0) and pelvic ROM (× 3.9), low FRR (× 4.9), delayed pelvic motion at 20o flexion (× 2.9), and longer movement duration (× 4.7). No differences between groups were seen for any sitting parameters. High pain intensity was significantly associated with small lumbar ROM and pelvic ROM.ConclusionSignificant movement differences during flexion were seen in people with LBP, with a higher prevalence of small ROM, slower movement, delayed pelvic movement and greater lumbar extensor muscle activation but without differences for any sitting parameter.Electronic supplementary materialThe online version of this article (10.1186/s12891-018-2387-x) contains supplementary material, which is available to authorized users.

Standardized difference scores are intuitive indexes which measure the effect size between two groups. Compared to a t-test or Wilcoxon rank-sum test, they are independent of sample size. Thus, their use can be recommended for comparing baseline covariates in clinical trials as well as propensity-score matched studies. In this paper, we show how to calculate sample standardized differences for continuous and categorical variables and how to interpret results. We also provide a SAS macro which performs the calculation without using the IML procedure.

Background Effective, inexpensive, and low-risk interventions are needed for patients with nonspecific persistent low back pain (NS-PLBP) who are unresponsive to primary care interventions. Cognitive functional therapy (CFT) is a multidimensional behavioral self-management approach that has demonstrated promising results in primary care and has not been tested in secondary care. Objective To investigate the effect of CFT and compare it with usual care for patients with NS-PLBP. Design Case–control study. Setting A secondary care spine center. Subjects Thirty-nine patients received a CFT intervention and were matched using propensity scoring to 185 control patients receiving usual care. Methods The primary outcome was Roland Morris Disability Questionnaire (0–100 scale) score. Group-level differences at six- and 12-month follow-up were estimated using mixed-effects linear regression. Results At six-month follow-up, a statistically significant and clinically relevant difference in disability favored the CFT group (–20.7, 95% confidence interval [CI] = –27.2 to –14.2, P &lt; 0.001). Significant differences also occurred for LBP and leg pain, fear, anxiety, and catastrophizing in favor of CFT. At 12-month follow-up, the difference in disability was smaller and no longer statistically significant (–8.1, 95% CI = –17.4 to 1.2, P = 0.086). Differences in leg pain intensity and fear remained significantly in favor of CFT. Treatment satisfaction was significantly higher in the CFT group at six- (93% vs 66%) and 12-month (84% vs 52%) follow-up. Conclusions These findings support that CFT is beneficial for patients with NS-PLBP who are unresponsive to primary care interventions. Subsequent randomized controlled trials could incorporate booster sessions, which may result in larger effects at 12-month follow-up.

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