Preoperative Spinal Sagittal Alignment Affects Improvement of Locomotive Syndrome by Four Years After Total Hip Arthroplasty.

Introduction Most patients with hip osteoarthritis requiring total hip arthroplasty suffer from locomotive syndrome stage 3, which indicates difficulty with mobility and social participation. Although total hip arthroplasty improves their locomotive syndrome stage, some patients remain at locomotive syndrome stage 3 after total hip arthroplasty, despite hip function improvement. Patients with severe hip osteoarthritis may have an abnormal spinal sagittal alignment. This study investigated the influence of preoperative spinopelvic parameters for locomotive syndrome improvement at four years after total hip arthroplasty. Methods This retrospective cohort study of a prospectively maintained database included 65 patients who had undergone total hip arthroplasty. Patients were divided into two groups based on whether they showed improvement from Locomotive Syndrome stage 3 at four years postoperatively: improved group (n = 51) and unchanged group (n = 14). Preoperative spinopelvic parameters were compared between the two groups and examined using logistic analysis to determine locomotive syndrome improvement. The cut-off values for preoperative key factors of locomotive syndrome improvement obtained using logistic analysis were determined using receiver operating characteristics analysis. Results Preoperative sagittal vertical axis was significantly larger and sacral slope was significantly smaller in the unchanged group than in the improved group. In the logistic regression analysis, preoperative sacral slope and the 25-question Geriatric Locomotive Function Scale (GLFS-25) were identified as factors associated with locomotive syndrome improvement. The receiver operating characteristic analysis showed that the cut-off values of preoperative sacral slope and GLFS-25 for locomotive syndrome improvement were 32.5° and 44.5, respectively. Conclusions Among hip osteoarthritis (OA) patients with locomotive syndrome stage 3, those who have small preoperative sacral slope and large preoperative GLFS-25 score may have difficulty improving their postoperative mobility. Therefore, it may be useful to suggest preoperatively that such patients should be prepared to use social services and other services after surgery to support their postoperative mobility.