BACKGROUND: It is important to understand chronological changes in pelvic tilt after total hip arthroplasty (THA). In this study, we first investigated changes in pelvic tilt after THA. Second, we determined the correlation between preoperative pelvic tilt and the extent of postoperative changes in the pelvic tilt. Third, we evaluated the effects of changes in pelvic tilt on postoperative function and disability. METHODS: We examined 149 patients who received primary THA over a follow-up period of 1 year. We compared postoperative changes with the preoperative pelvic tilt on the basis of the anterior pelvic plane (APP) defined by DiGioia and patient demographics. RESULTS: A significant correlation was observed between preoperative APP and the amount of postoperative change in APP, suggesting that patients with severe preoperative pelvic tilt generally experience greater postoperative changes in pelvic tilt. Our data showed that patients with preoperative anterior pelvic tilt generally exhibit posterior changes in pelvic tilt after operation, while patients with preoperative posterior pelvic tilts did not experience significant postoperative changes in pelvic tilt. The 1-year postoperative function scores in patients with preoperative anterior pelvic tilt were lower than those in patients with preoperative posterior pelvic tilt. CONCLUSIONS: Pelvic tilt changed by varying degrees following THA. Special attention must be paid when positioning the acetabular component, particularly in patients with severe pelvic tilt prior to surgery. A greater understanding of the postoperative changes in pelvic tilt may improve the outcome of THA.
BACKGROUND: It is important to understand chronological changes in pelvic tilt after total hip arthroplasty (THA). In this study, we first investigated changes in pelvic tilt after THA. Second, we determined the correlation between preoperative pelvic tilt and the extent of postoperative changes in the pelvic tilt. Third, we evaluated the effects of changes in pelvic tilt on postoperative function and disability. METHODS: We examined 149 patients who received primary THA over a follow-up period of 1 year. We compared postoperative changes with the preoperative pelvic tilt on the basis of the anterior pelvic plane (APP) defined by DiGioia and patient demographics. RESULTS: A significant correlation was observed between preoperative APP and the amount of postoperative change in APP, suggesting that patients with severe preoperative pelvic tilt generally experience greater postoperative changes in pelvic tilt. Our data showed that patients with preoperative anterior pelvic tilt generally exhibit posterior changes in pelvic tilt after operation, while patients with preoperative posterior pelvic tilts did not experience significant postoperative changes in pelvic tilt. The 1-year postoperative function scores in patients with preoperative anterior pelvic tilt were lower than those in patients with preoperative posterior pelvic tilt. CONCLUSIONS: Pelvic tilt changed by varying degrees following THA. Special attention must be paid when positioning the acetabular component, particularly in patients with severe pelvic tilt prior to surgery. A greater understanding of the postoperative changes in pelvic tilt may improve the outcome of THA.