Comparison of Postural Balance between Subgroups of Nonspecific Low-back Pain Patients Based on O’Sullivan Classification System and Normal Subjects during Lifting

Abstract

Background: Balance disorder is one of the most-studied fields in low-back pain patients (LBP). However, there is<br />insufficient information regarding the effect of LBP subgrouping on postural control. The purpose of the present study<br />was to compare postural control between subgroups of chronic nonspecific LBP and healthy subjects during lifting.<br />Methods: A total of 35 men with chronic LBP (19 active extension pattern [AEP] and 16 flexion pattern [FP]) and 15<br />healthy controls were enrolled in this cross-sectional study. Pooled LBP was subdivided based on the O'Sullivan's<br />classification system (OCS). The participants were asked to lift a box from the ground to the waist level and hold it for<br />20 seconds. The load was 10% of the subject's weight. Force plate system was used to record balance parameters,<br />including standard deviations (SDs) of center of pressure (COP) amplitude and COP velocity in anterior-posterior and<br />medial-lateral directions and mean total velocity. The test was divided into two static and dynamic phases. Data were<br />analyzed using one-way analysis of variance and independent t-test.<br />Results: There were no significant differences between pooled LBP and control groups in any of the variables, except<br />for the SD of the anterior-posterior direction velocity in the X-plane in the static phase (P=0.017). After classifying LBP,<br />the results showed that the healthy and AEP groups were significantly different in SD of COP velocity in the frontal plane<br />(P=0.021), mean total velocity (P=0.010), and SD of COP velocity in the sagittal plane (P=0.039).<br />Conclusion: The present study showed that postural control was not different between the pooled LBP and normal<br />groups. After classifying pooled LBP based on OCS, we found that the AEP showed different postural control as<br />compared to healthy controls in the dynamic phase. The FP and AEP exhibited different postural control relative to the<br />healthy controls in the static phase, and COP velocity was lower in those groups compared to the control group. The<br />results of this study support the concept of LBP classification.