PREOPERATIVE 3D MODELING AND PRINTING FOR GUIDING PERIACETABULAR OSTEOTOMY

BACKGROUND: Achieving adequate acetabular correction in multiple planes is essential to the success of Periacetabular Osteotomy (PAO). Three-dimensional (3D) modeling and printing has the potential to improve preoperative planning by accurately guiding intraoperative correction. HYPOTHESIS/PURPOSE: We, therefore, asked the following questions: 1) For a patient undergoing a PAO, does 3D-modeling with intraoperative 3D-printed models create a reproducible surgical plan to obtain predetermined parameters of correction including lateral center-edge angle (LCEA), anterior center-edge angle (ACEA), Tonnis angle, and femoral head extrusion index (FHEI), 2) Can 3D computer modeling accurately predict when a normalized FHEI can be achieved without the need for a concomitant femoral sided osteotomy? METHODS: A retrospective review was conducted on forty-two (42) consecutive patients that underwent a PAO. 3D-modeling software was utilized to simulate a PAO in order to achieve normal LCEA, ACEA, Tonnis angle, and FHEI. If adequate FHEI was not achieved, a femoral osteotomy was simulated. 3D-models were printed as intraoperative guides. Preoperative, simulated, and postoperative ACEA, LCEA, Tonnis angle, and FHEI were measured and compared statistically. RESULTS: 40 patients had a traditional PAO, and 2 had an anteverting-PAO. The simulated LCEA, ACEA, Tonnis angle, and FHEI were within a median difference of 3º, 1º, 1°, and 0% of postoperative values, respectively and showed no statistical difference. Of those that had a traditional PAO, all thirty-four (34) patients were correctly predicted to need a traditional acetabular sided correction alone and the other six (6) were correctly predicted to need a concomitant femoral osteotomy for a correct prediction in 100% of patients. CONCLUSION: This study demonstrated that in PAO, 3D-modeling and printing allow the surgeon to accurately create a reproducible surgical plan to obtain predetermined postoperative hip coverage parameters. This new technology has the potential to improve preoperative/intra-operative decision making for hip dysplasia and other complex disorders of the hip.