Differences in measurements of lumbar curvature related to gender and low back pain

STUDY DESIGN: Cross-sectional. OBJECTIVES: To test the assumption that postural alignment and gender have a bearing on the specific type of low back pain (LBP) a person manifests. BACKGROUND: Measurements of static sagittal lumbar curvature are used by clinicians in the management of patients with LBP, but no investigator has reported differences in curvature related to specific categories of LBP. METHODS AND MEASURES: We used a computer-interfaced, 3-D, electromechanical digitizer to derive curvature angles for the region of the spine between T12-L1 and S2. Trained clinicians examined the subjects and determined their LBP diagnoses. We used t tests to examine differences in curvature between women and men, those with and those without LBP, and those in 4 different categories of LBP. We used chi2 to examine the relationship between gender and LBP category. RESULTS: Lumbar curvature angle (lordosis) was 13.2 degrees larger for women than for men (t = 6.74; P<.01). There was no difference in lumbar curvature between people with undifferentiated LBP and people without LBP. There were differences in lumbar curvature between people in various categories of LBP, for example, subjects in the lumbar-rotation-with-extension category had 8.4 degrees more lumbar curvature than subjects in the lumbar-rotation-with-flexion category (t = 2.16; P<.05). Based on the frequency distributions, there was a significant relationship between gender and LBP category (chi2 = 10.19; P<.01). CONCLUSIONS: Measurements of lumbar curvature should be expected to differ between men and women and may be related to different types of low back pain.