Postural control of patients with nonspecific chronic low back pain during functional tasks measured by two platforms simultaneously

Abstract

Introduction: Low back pain is highly prevalent in Brazil and in the World. Postural control represents one of the functional limitations of low back pain. Postural control can be investigated through the behavior of the center of pressure (CoP), using a
baropodometry that is a lower cost instrument when compared to the standard gold instrument (i.e., force platform). However, there is a lack of clinimetric information on the stabilometric parameters of the computed baropodometry in agreement with the force platform. In addition, the postural control of patients with chronic low back pain during functional tasks was poorly investigated in the literature. Objective: To verify the concurrent validity of the measurement of CoP displacement measured by baropodometry in people with chronic nonspecific low back pain during functional activities. Secondarily, the present study compared the postural control of patients with non-specific chronic low back pain and controls during functional activities. Methods: An accuracy diagnosis study and observational, analytical study was performed in 42 participants with chronic low back pain and 42 controls matched for age, sex and body mass index. Participants performed functional tasks on a baropodometer that was on top of a force platform with signals being aligned accordingly by the time. The functional activities evaluated in baropodometry were: remain in the orthostatic posture, bipedal support holding bags and Bipedal Squatting holding Bags. The validation concurrent of the measure of CoP displacement measured by baropodometry in agreement with the force plate was investigated by Pearson's correlation and Bland-Altman method. The CoP oscillation behavior of the two groups (patients x controls) was compared. Results: Our findings showed a moderate to strong correlations in most of the measures investigated. The Bland-Altman analyses revealed substantive differences between the two methods in the majority of the parameters of the CoP displacement examined. Accordingly, linear regression equations to predict the values of the force plate from the baropodometer results were calculated. Secondarily, the total sway mean velocity, mean velocity mediolateral and, mean velocity anteroposterior presented differences statistically significant within-group and between- group (P<0.05) while performed the last task BSBS. Conclusion: The baropodometer is validity to measure the displacement of the CoP in patients with non-specific low back pain when compared to the force plate. The patients with nonspecific chronic low back pain presented lower mean velocity of CoP while compared with controls healthy performing the Bipedal Squatting holding Bags.