Movement control tests of the low back; evaluation of the difference between patients with low back pain and healthy controls

Background: To determine whether there is a difference between patients with low back pain and healthy controls in a test battery score for movement control of the lumbar spine. Methods: This was a case control study, carried out in five outpatient physiotherapy practices in the German-speaking part of Switzerland. Twelve physiotherapists tested the ability of 210 subjects ( 108 patients with non-specific low back pain and 102 control subjects without back pain) to control their movements in the lumbar spine using a set of six tests. We observed the number of positive tests out of six ( mean, standard deviation and 95% confidence interval of the mean). The significance of the differences between the groups was calculated with Mann-Whitney U test and p was set on < 0.05. The effect size (d) between the groups was calculated and d > 0.8 was considered a large difference. Results: On average, patients with low back pain had 2.21( 95% CI 1.94-2.48) positive tests and the healthy controls 0.75 ( 95% CI 0.55-0.95). The effect size was d = 1.18 ( p < 0.001). There was a significant difference between acute and chronic ( p < 0.01), as well as between subacute and chronic patient groups ( p < 0.03), but not between acute and subacute patient groups ( p > 0.7). Conclusion: This is the first study demonstrating a significant difference between patients with low back pain and subjects without back pain regarding their ability to actively control the movements of the low back. The effect size between patients with low back pain and healthy controls in movement control is large.