Abstract
Introduction
Acetabular cup positioning has been linked to dislocation and increased bearing surface wear. A previous study found correlations between patient and surgical factors and acetabular component position. The purpose of this study was to determine if acetabular cup positioning improves when surgeons receive feedback on their performance.
Methods
Post-op anteroposterior (AP) pelvis and cross-table lateral radiographs were previously obtained for 2061 patients who received a total hip arthroplasty (THA) or hip resurfacing from 2004–2008. The surgeries were performed by 7 surgeons. AP radiographs were measured using Hip Analysis Suite to calculate the cup inclination and version angles. Acceptable ranges were defined for abduction (30–45 °) and version (5–25 °). The same surgeons performed a THA or hip resurfacing on 385 patients from January 2009 through June 2010. Cup inclination and version angles for this set of surgeries were compared to surgeries from 2004–2008 to determine if cup inclination and version angles improved in response to previous acetabular cup positioning studies. Improvement in accuracy was assessed by the chi-square test.
Results
Time 1, from 2004 through 2008, had 1952 qualifying hips with 1845 having both version and abduction, and Time 2, from 2009 through June 2010, had 385 qualifying hips, all of which had both version and abduction angles. For Time 1, 1192 (62%) acetabular cups were within the abduction range, 1422 (79%) were within the version range, and 908 (49%) were within the range for both. For Time 2, 276 (72%) acetabular cups were within the abduction range, 250 (65%) were within the version range, and 217 (56%) were within the ranges for both. Accuracy of abduction angle improved (p<0.01) while accuracy of version angle decreased (p<0.01). Accuracy of acetabular cup positioning being within range for both abduction angle and version angle improved significantly (p=0.01), by 7%.
Conclusions
Increased awareness and feedback on the resulting abduction and version measurements from THA surgery over time improves the positioning of the acetabular component. A system where objective measurements are presented to the surgeon can significantly improve cup placement which could improve the clinical outcome of THR patients.
