Postural stability measurement during Y-balance test increases chronic low back pain assessment sensitivity

People with chronic low back pain (CLBP) experience decreased balance, which is made of postural maintenance and postural control domains. Postural maintenance can be measured from Center of Pressure (COP) movement variables, while postural control can be measured from leg reach during Y-Balance Test (YBT).

Can COP measurement during YBT assess CLBP status? Does COP measurement in addition to reach during YBT improve CLBP assessment?

Forty-four CLBP and twenty-two healthy participants executed YBT on force platform with three-dimensional motion capture system measuring the trunk and lower limb joint active range of motion (AROM). One-way multivariate analysis of covariance (MANCOVA) assessed the difference of outcome variables between healthy and CLBP participants. Binomial logistic regression assessed the sensitivity of individual variables and their combination in CLBP screening.

People with CLBP have decreased postural maintenance, as quantified by an increased normalized mean velocity (nMVEL) (p = 0.006) in anterior, (p = 0.015) posteromedial and (p = 0.016) posterolateral directions, along with decreased normalized leg reach (nReach), compared to healthy participants. They also have decreased postural control as quantified by decreased nReach that is positively correlated with joints AROM, not to nMVEL, in all directions. Combed nMVEL and nReach in posteromedial direction provided the best predictive model for CLBP screening within the study demographics.

Objective measure of postural stability, particularly nMVEL during YBT that assess a separate dimension of stability relative to leg reach (nReach) can enhance CLBP screening sensitivity.