The Effect of a Pelvic Support Chair on Sagittal Lumbosacral Alignment in Sitting Position in Patients with Lower Back Pain

BACKGROUND: A slouched lumbar posture during sitting is risk factor for the low back pain (LBP). Various chairs have been used to maintain sagittal lumbar lordosis and sacral alignment during sitting. We aimed to demonstrate the effect of a pelvic-support chair on the lumbar lordosis and sacral tilt in patients with LBP. METHODS: We recruited 29 patients with non-specific LBP and 11 healthy subjects in South Korea from Apr 2017 to Mar 2018. The sagittal lumbosacral alignment was examined radiographically in three sitting postures: usual, erect, and sitting in a pelvic-support chair. Five angles [the lumbar lordosis, upper lumbar (ULA), lower lumbar (LLA), lumbosacral (LSA), and sacral slope (SS) angles] were compared between the subjects with LBP and healthy subjects in the three sitting conditions. RESULTS: There were significant differences in the lumbar lordosis, ULA, LLA, LSA, and SS according to sitting condition (P<.05). All five angles were significantly greater when participants sat erect or in a pelvic-support chair than in their usual sitting position (P<.05). ULA and SS were significantly greater when sitting erect than in a pelvic-support chair (P<.05). LLA was significantly greater in controls than in patients with LBP (P=.042). CONCLUSION: The sagittal alignment of the lumbosacral region differed significantly among usual, erect, and pelvic-support chair sitting in patients with LBP and controls. Decreased lordotic curve of the lumbar spine in the usual sitting position can be changed in both patients with LBP and healthy subjects by sitting with pelvic support chair.