Cheating the Acetabular Component Horizontally in Total Hip Arthroplasty

To avoid inadvertent vertical positioning of the acetabular component during total hip arthroplasty (THA), the authors routinely "cheat" component abduction an additional 10 degrees horizontal (goal=30 degrees). This likely increases the incidence of components placed into abduction of less than 30 degrees, the clinical consequences of which are not well studied. The purpose of this study was to determine the clinical and radiographic outcomes in patients undergoing THA with acetabular components positioned in less than 30 degrees of abduction as compared with those with components positioned between 30 degrees and 50 degrees. A retrospective review was performed of consecutive patients undergoing primary THA with horizontally cheated acetabular component position performed by a single surgeon. Patients were grouped into cohorts with either component abduction less than 30 degrees or between 30 degrees and 50 degrees. Demographic data, operative data, and complications were recorded. Harris Hip Scores (HHS) and radiographic analysis were obtained from preoperative and most recent clinic visits. Between September 2004 and September 2010, 320 consecutive THA procedures were performed. A total of 149 hips had component abduction less than 30 degrees (mean, 25.8 degrees; range, 15.7 degrees-29.4 degrees). No components had greater than 50 degrees of abduction. At an average 37-month follow-up, no significant difference in HHS was found between the 2 cohorts (P=.137). The horizontal cohort had no dislocations, component loosening, or osteolysis. By cheating the acetabular component more horizontal, an excessively vertical position was avoided. Component abduction less than 30 degrees yielded equivalent clinical outcomes to component abduction between 30 degrees and 50 degrees.