The effect of total hip arthroplasty on sagittal spinal-pelvic-leg alignment and low back pain in patients with severe hip osteoarthritis

Abstract

Purpose: Sagittal spinopelvic malalignment has been reported in spinal disorders such as low back pain (LBP), and restoration of normal alignment is targeted when treating these disorders. Abnormal sagittal spinal-pelvic-leg alignment has been reported in patients with severe hip osteoarthritis (OA), who have a high prevalence of associated LBP. This prospective longitudinal study aimed to investigate changes in sagittal spinal-pelvic-leg alignment after total hip arthroplasty (THA) in patients with severe hip OA, and whether these changes contribute to LBP relief.

Methods: Patients undergoing primary THA due to severe unilateral hip OA were recruited. Physical examination and X-ray films were taken to rule out any spinal disorder. Sagittal alignment of pelvis, hip, and spine was analyzed on lateral radiographs taken before (baseline) and 1 year after (follow-up) THA. Functional instruments were completed by patients including: visual analog scale (VAS) for LBP, Roland-Morris Disability Questionnaire (RMDQ), and Harris Hip Score (HHS). Comparisons were carried out at baseline and follow-up, and between patients with and without LBP.

Results: The recruited 69 patients showed significantly reduced hip flexion and improved global spinal balance at follow-up compared with baseline. LBP was reported by 39 patients (56.5 %) before surgery; at follow-up, 17 reported complete resolution, while 22 reported significant relief. Significant decreases in VAS and RMDQ scores in lumbar spine and increase in hip HHS were observed.

Conclusions: THA in patients with severe hip OA could help correct abnormal sagittal spinal-pelvic-leg alignment and relieve comorbid LBP. Improvements in hip flexion and global spinal balance might be involved in the mechanism of LBP relief.

Keywords: Hip flexion; Low back pain; Osteoarthritis; Sagittal alignment; Total hip arthroplasty.