Visual and instrumental diagnostics using chromokinegraphics: Reliability and validity for low back pain stratification

BACKGROUND: Low back pain patients have been suggested to exhibit dysfunctional spinal movement patterns. However, there is a lack of clinically applicable but valid and reliable assessment tools, helping to discriminate normal and pathologically altered movement. OBJECTIVE: We aimed to examine whether kinematic parameters determined with an ultrasound-based motion analysis and thereof derived chromokinegraphical angle-time matrices (CATMAs) are able to discriminate between non-symptomatic and symptomatic movement behaviour in individuals with non-specific chronic (CLBP), specific low back pain (SLBP), and controls. METHODS: Thoracic and lumbar spine range of motion (ROM [∘]); angular velocity (V [∘/sec]) and side-to-side differences [%] during a lateral flexion movement were assessed in 17 healthy participants, 16 individuals with CLBP and 11 SLBP patients. CATMAs ratings of two investigators (6-item Likert scale) were dichotomised, classifying the observed movement as physiological or non-physiological. Intrarater and interrater reliability were estimated using kappa statistics and Cronbach's Alpha. T-tests and a ROC analysis to determine optimal cut-offs for the separation of the collectives as well as contingency tables for selectivity of the cut-offs (motor outcomes) were calculated. RESULTS: CATMA ratings displayed partly moderate to good (rater B; i.e. CLBP vs. controls) and partly insufficient discriminant validity (rater A). Due to this, inter-rater reliability was poor (k= 0.061 to 0.135), while intra-rater-reliability was moderate to good for both raters (k= 0.329 to 0.625) except for SLBP vs. controls (rater A; k=-0.18). Regarding kinematics, group differences occurred neither in ROM nor in V (p> 0.05), but in terms of the relative side comparison between CLBP and controls (p<0.05). ROC analysis (CLBP vs. controls) revealed an optimal cut-off at side asymmetries of 16.9% (ROM) and 28.9% (V). Between SLBP patients and controls, no significant differences were observed neither in terms of the absolute values nor the relative side differences of both kinematic variables. CONCLUSIONS: Side asymmetries of V and ROM may be used to differentiate between controls and individuals with CLBP. CATMAs appear to be of limited diagnostic value for the identification of pathological spine movement.