Comparison of the reliance of the postural control system on the visual, vestibular and proprioceptive inputs in chronic low back pain patients and asymptomatic participants

Background: Although proprioception deficits have been documented in chronic low back pain (CLBP) patients, little is known about adaptive strategies to provide postural control in these patients. Substitution of unreliable proprioceptive information with other afferents might be considered plausible. Research question: Is the response of the postural control system dependent on the source of sensory afferents being manipulated in persons with and without CLBP? Methods: Sixty persons with and without CLBP participated in this cross-sectional study. Center of pressure (COP) displacement range, velocity, path length and area were calculated under four sensory conditions: 1) normal upright standing; 2) upright standing on a foam with eyes open and head in neutral position; 3) upright standing with eyes open and 60? cervical extension and 4) upright standing with eyes closed and 60? cervical extension. A two-way repeated measures analysis of variance was used to compare COP masseurs under different conditions and between the groups. Results: CLBP patients demonstrated fewer alterations to manipulation of both visual and vestibular afferents in terms of number of COP variables significantly altered. ML range and velocity in both groups and path length in the CLBP group were significantly different between conditions 2 and 4. In both groups, all COP variables except AP range increased significantly in condition 2 compared to conditions 1and 3 (p < 0.001). AP velocity was the only variable to be different between conditions 1 and 3 in both CLBP (p = 0.025) and control (p < 0.001) groups. Between group differences were significant on AP velocity (p = 0.019). Significance: No overweighting was observed in the vestibular or visual afferents in CLBP patients. Compensatory strategies seem to lie within proprioceptive system by reweighting afferents from different body segments. The postural control system behaved more robustly in CLBP patients while AP COP velocity was found as the most sensitive and discriminating parameter.