Concurrent validation of the centre of pressure displacement analysed by baropodometry in patients with chronic non-specific low back pain during functional tasks

ABSTRACT Introduction Low back pain is highly prevalent worldwide and in Brazil. Postural control is a functional limitation in patients with low back pain. Postural control can be investigated through the centre of pressure (CoP) displacement, using a baropodometry. However, there is a lack of validation data about posturography variables obtained from the baropodometer. This study aimed to investigate the concurrent validity of the displacement of CoP measured through baropodometer T-Plate® in patients with chronic non-specific low back pain during three tasks. Method A validation study was conducted in 37 participants with chronic non-specific low back pain during three different tasks, including bipedal support, bipedal support holding bags, and bipedal squatting holding bags. The tasks were performed on a baropodometer (index method) placed on a force plate (criterion measure). Measurements included velocity, amplitude of displacement, and sway area. Results Weak to strong correlations were found in the three tasks between the baropodometer and the force plate for most variables. The Bland-Altman analyses revealed no substantive differences between the two methods for the standard deviation of amplitude mediolateral and sway area for the three tasks. There was a systematic bias for the mean velocity and the standard deviation of amplitude anteroposterior displacement in the three tasks. Conclusion The baropodometer could be used to measure the displacement of the CoP in patients with chronic non-specific low back pain. Sway area showed an appropriate validity to measure postural stability of the participants using the baropodometer.