Resistive straight leg raise test, resistive forward bend test and heel compression test: novel techniques in identifying secondary gain motives in low back pain cases.

Abstract

'Low back pain' (LBP) is a prevalent condition with a majority showing no specific organic pathology. Distinguishing 'secondary gain motives (SGM)' from organic causes is imperative in clinical practice. We describe here, three new tests-resistive straight leg raise test (rSLRT), resistive forward bend test (rFBT) and heel compression test (HCT) to help differentiate patients with 'SGM' from those without. We conducted a prospective study to validate the above tests in predicting non-organic causes as a reason for LBP. 200 patients presenting with low back pain at the senior author's outpatient orthopaedic clinic from Jan 2009 to Nov 2010 were studied. Patients were separated into two groups-'SGM group' (n = 100) and 'non-SGM group' (n = 100). 'SGM group' patients had a history of work-related accidents, road traffic accidents or assault, with a background of ongoing litigation issues or compensation benefits. rSLRT, rFBT, HCT, Schober's test and Waddell's five signs were performed on them. Statistical analysis was done to identify correlations between test results, MRI findings and 'SGM' status. Statistically significant differences were observed between the SGM and non-SGM group (p < 0.0005) for all tests studied. In predicting SGM status, rSLRT showed highest specificity (0.94) and highest positive predictive value (0.925) while HCT showed the highest negative predictive value (0.859). Positive rSLRT was found to be strongly correlated with ≥3 positive Waddell's signs. SGM patients with positive rSLRT tended to show resistance ≤45°. rSLRT, rFBT and HCT (NK triad) are highly practical tests which strongly predict SGM status in patients.