The accuracy of a patient-specific femoral planning and delivery system for total hip arthroplasty.

Introduction: A primary objective when performing a total hip arthroplasty (THA) is to restore hip biomechanics in accordance with a chosen surgical plan. The aim of this study was to assess the accuracy of a 3D-printed patient-specific guide for delivering a planned femoral osteotomy for both a posterior and an anterior approach.

Methodology: 40 patients (20 anterior and 20 posterior) scheduled for THA received a preoperative work-up allowing for patient-specific implant sizing and positioning. Following surgeon confirmation, a patient-specific guide was designed and printed, enabling the desired osteotomy to be executed. Achieved osteotomies were assessed using commercially available software platforms. Planning accuracy was also assessed using both the planning platform as well as more traditional 2D-templating techniques.

Results: The mean deviation between the planned and achieved osteotomy level was -0.6 mm (range -4.1-6.4 mm). 95% of the achieved osteotomy levels were within 3 mm of the plan for both the posterior and anterior approach groups. 70% of the Optimized Positioning System (OPS) planned femoral components were the exact size as planned versus 25% of the 2D-planned components. 98% of the OPS planned femoral components were within 1 size of plan versus 58% for the 2D-planned components. No sizing accuracy difference was observed between planning approaches (p = 0.70).

Conclusions: A patient-specific osteotomy guide can be a simple and accurate method to reproduce a planned femoral neck resection through an anterior or posterior approach. Further, 3D planning appears to more accurately predict femoral sizing in THA than more conventional 2D methods.