Increased anterior pelvic tilt in patients with acetabular retroversion compared to the general population: A radiographic and prevalence study

Introduction:The prevalence of acetabular retroversion is sparsely investigated. It may be associatedwith increased anterior pelvic tilt. The purpose of this study was to investigate whether patients withsymptomatic and radiographically verified acetabular retroversion demonstrated increased anteriorpelvic tilt compared to a control group, and furthermore to evaluate the prevalence of acetabularretroversion in the general population.Methods:Anteroposterior pelvic radiographs in standing position of 111 patients with acetabularretroversion prior to anteverting periacetabular osteotomy (PAO) and 132 matched controls from thegeneral Danish population were assessed. Pelvic tilt was assessed by thesacrococcygeal jointesymphysisdistanceandpelvic-tilt-ratio. Acetabular retroversion was defined as positive cross-over sign and pos-terior wall sign. Prior to assessments, interrater reliability analysis was performed. Measurements wereagreed by two independent assessors. A nonparametric regression model was used to test between-group differences in median pelvic tilt. The prevalence was calculated as the ratio of subjects and hipswith acetabular retroversion, respectively.Results:The patient group had significantly larger median anterior pelvic tilt of 14.3 mm insacro-coccygeal jointesymphysis distanceand0.08 inpelvic-tilt-ratio,compared to controls. The prevalence ofsubjects in the general population with either unilateral or bilateral acetabular retroversion was 24% and18% for all hips.Conclusion:Our data demonstrated that patients with symptomatic acetabular retroversion haveincreased anterior pelvic tilt compared to the general population. Radiographic sign of acetabularretroversion was highly prevalent in the general population.Implication for practice:Increased anterior pelvic tilt should be considered when diagnosing and treatingpatients with hip pain, as symptoms may be related to the functional position of the pelvis and notnecessarily solely come from the radiographic verified acetabular retroversion.