The Accuracy of Acetabular Cup Positioning Using Patient-Specific 3D Orientation Guidance in Total Hip Arthroplasty.

Introduction: Malpositioning of the acetabular cup during total hip arthroplasty (THA) increases the risk of certain complications and shortens the lifespan of the prosthetic joint. Therefore, the accurate placement of the acetabular component during a THA is a necessary contributing factor to its successful outcome. The different methods of intraoperative estimation of acetabular component positioning are quite varied and sometimes may be inaccurate. The purpose of this study was to assess the accuracy of intraoperative acetabular component orientation with the assistance of three-dimensional (3D), patient-specific guidance alone.

Materials And Methods: At a single institution, a total of 56 patients were prospectively enrolled into this study. Acetabular cup positioning was achieved with a described method using a laser beam technique minus the placement of pelvic pins. Comparison was made between the planned, preoperative inclination and version angles with the achieved postoperative inclination and version of the acetabular component in all THAs performed. The accuracy of placement of the acetabular cup was assessed using postoperative computed tomography (CT) scans. Evaluation was performed by an independent orthopaedic surgeon.

Results: Fifty-eight hips were included in the present study. The mean absolute deviation from the preoperative planned inclination and anteversion was 4.0° (0.1° to 14.6°; p<0.05) and 4.4° (0.2° to 12.2°; p<0.05) respectively. The planned inclination and anteversion were achieved within a +/- 10° target in 98% of the cases respectively.

Conclusion: Accuracy of acetabular cup orientation in total hip arthroplasty can be achieved to a high degree with 3D patient-specific guidance alone. This eliminates the pins in the pelvis and has the potential to reduce costs and patient trauma without impacting accuracy.