Three-dimensional technology assisted trabecular metal cup and augments positioning in revision total hip arthroplasty with complex acetabular defects

BACKGROUND: Revision total hip arthroplasty (THA) with large acetabular defect remains a challenge. Though trabecular metal (TM) cup and augments have been introduced in defect reconstruction with good result, the accurate positioning of implant is important to avoid complications. Therefore, we aimed to evaluate the usefulness of three-dimensional (3D) simulation and 3D model in assisting implant positioning during complex revision THA. METHODS: Sixteen patients (18 hips) who underwent revision THA with a Paprosky type III acetabular defect were analyzed retrospectively. Placement of acetabular cup and TM augments was simulated with 3D simulation software and 3D model preoperatively. Cup anteversion, abduction angle, and hip center were measured in each case preoperatively and postoperatively. Primary outcome was the percentage of outliers according to Lewinnek safe zone and Harris hip score (HHS). Secondary outcome was the correlation between the 3D planned and the postoperative value. RESULTS: The percentage of outliers was significantly corrected from 77.78% (14/18) preoperatively to 38.88% (7/18) postoperatively (p = 0.04). There was a significant correlation between mean planned cup anteversion and postoperative value (13.39 vs 11.99, r = 0.894; p < 0.001). There was a significant correlation between mean planned abduction and postoperative value (42.67 vs 44.91, r = 0.921, p < 0.001). The number of planned and used augments was the same in all the cases. In 15 cases (83.33%), the size of planned and used TM augments was the same. The HHS was significantly improved at final follow-up (80.94 vs 27.50, p < 0.001). No cases presented dislocation or radiological signs of loosening. CONCLUSION: Preoperative 3D simulation and model were considered the useful method to assist implant positioning in revision THA with complex acetabular defect, with moderate to high accuracy and satisfied clinical outcome.