Effects of load and unstable support surface on postural control in patients with chronic low back pain

Abstract

Introduction: Several studies have demonstrated the postural control alterations in patients with low back pain. However, the difference in center of pressure (COP) parameters in the body sway in unstable conditions is relatively unknown in these patients. Therefore, the aim of the present study was to investigate the effects of unstable load and support surface on postural control in chronic low back pain (CLBP) patients. Materials and methods: CLBP patients (n=20) (mean age 31.30 years and mean BMI 25.20 kg/m2) and 20 healthy subjects (mean age 30.00 years and mean BMI 24.12 kg/m2) were asked to hold a load weighing 10 percent of their body weight while standing. Experimental conditions were manipulated based on stability of load (stable or unstable) and support surface (firm or foam). Using a force plate, COP sway parameters including sway amplitude (and its standard deviation) and sway velocity (and its standard deviation) in anteroposterior (AP) and mediolateral (ML) directions were measured. Results: Patients with CLBP exhibited less AP sway amplitude compared to control subjects (P=0.03). Furthermore, they had less ML sway velocity while holding the unstable load (P=0.05) and more ML sway amplitude while standing on foam (P=0.04). Conclusion: In compare to healthy subjects, patients with CLBP demonstrated a different pattern of postural control during instability of load and support surface. In these conditions, altered proprioception and stiffening strategy can increase the risk of spine injuries