The Ratio of Lumbar to Hip Motion during the Trunk Flexion in Patients with Mechanical Chronic Low Back Pain According to O’Sullivan Classification System: A Cross-sectional Study

Abstract

Background: Static and dynamic postures of lumbopelvic in low back pain (LBP) are considered as two important<br />aspects of clinical assessment and management of LBP. Thus, the focus of the current study was to compare the<br />posture and compensatory strategy of hip and lumbar region during trunk flexion between LBP subgroupsand health<br />subjects. LBP cases are subdivided into active extension pattern (AEP) and flexion pattern (FP) based on O'Sullivan's<br />classification system (OCS).<br />Methods: This work was a cross-sectional study involving 72 men, 21 low back pain patients with FP and 31 low back<br />pain patients with AEP and 20 healthy groups. Lumbar and hip angles during trunk flexion were measured by a 3D<br />motion analysis system in neutral standing posture and end-range of trunk flexion. The participants were asked to full<br />bend without any flexion of the knees. The bending speed was preferential. Hip and lumbar ranges of motion were<br />divided into four quartiles (Q). The quartiles were compared between groups. Data analysis was performed using oneway<br />analysis of variance (ANOVA) and independent t-test.<br />Results: There was no statistically significant difference in lumbar lordosis in standing and full trunk flexion positions<br />between the healthy groups and heterogeneous LBP groups. In addition, there was not any statistically significant<br />difference between the healthy group and the homogenous LBP group (FP and AEP). Moreover, no statistically significant<br />difference was observed in hip angles during standing between the healthy group and the heterogeneous LBP group,<br />and between the healthy group and the homogenous LBP group (FP and AEP). In full trunk flexion position, there was<br />statistically significant difference in hip angles between the healthy group and the heterogeneous LBP group (P=0.026).<br />In this position, the difference in hip angles between the healthy group and FP group was statistically significant<br />(P<0.05). In the second Q, there was no significant difference between the healthy group and the heterogeneous LBP<br />group (P=0.062), however, there was a significant difference between FP group and the healthy group in the fourth<br />Q of the total hip range of motion. There was no statistically significant difference between the healthy group and the<br />heterogeneous LBP group (P=0.054) but there was a difference between FP group and the healthy group. Lumbar/hip<br />motion ratio (L/H ratio) was different between and within the subgroups in the second Q.<br />Conclusion: This study supported the subgrouping of LBP and showed that the difference between subgroups could<br />be determined effectively through subdividing the total range of lumbar and hip motions into smaller portions. It is<br />possible that the neuromuscular system selects different strategies to compensate and prevent further injury of the<br />chain components (muscle, joint, nerve and etc.).<br />Level of evidence: IV