Background: Until now, cementless total hip arthroplasty (THA) has been mainly performed using a manual technique involving a hammer and impactor. During cup insertion into the acetabulum, the manual technique may cause temporary limitations in visual...
Background: Until now, cementless total hip arthroplasty (THA) has been mainly performed using a manual technique involving a hammer and impactor. During cup insertion into the acetabulum, the manual technique may cause temporary limitations in visualization, discrepancies in the applied force, and imbalance in the force vector. Recently, automatic impaction devices have been developed and adopted for cup insertion. The purpose of this study is to compare the accuracy of cup positioning in primary THA between the manual technique and the automatic impaction device.
Methods: A total of 67 hips were retrospectively evaluated: 36 hips via manual technique and 31 hips via automatic impaction device for primary THA. The accuracy of acetabular cup positioning between the two groups was compared using the Lewinnek's safe zone, which indicates accurate cup placement, based on postoperative measurements of cup anteversion and inclination angle. Six methods for measuring anteversion were applied in this study. In addition, the incidence of acetabular screw augmentation, and the occurrence of intraoperative and postoperative complications up to one year after surgery were assessed.
Results: The proportion of cases positioned within the Lewinnek’s safe zone was higher in the automatic group than in the manual group across all measurement methods. Regarding postoperative complications, one episode of dislocation occurred in the manual group, but it did not show statistically significant differences.
Conclusion: Automatic impaction device can improve the accuracy of THA cup positioning than manual technique.
Keywords: Automatic impaction device, Total hip arthroplasty, Acetabular cup positioning