Preoperative Use of a 3D Printed Model for Femoroacetabular Impingement Surgery and Its Effect on Planned Osteoplasty.

ABSTRACT

OBJECTIVE: The purpose of this study was to determine the effect that preoperative use of 3D printed models has on planned osteoplasty for femoroacetabular impingement (FAI) surgery. MATERIALS AND METHODS: This experimental study utilizing retrospective data included 10 consecutive patients from July 1, 2013, to January 1, 2015, with a clinical diagnosis of FAI and imaging consisting of radiographs, CT scans, and MR images. Three-dimensional models of each patient's affected hip were printed to scale from CT data. Two orthopedic surgeons evaluated each patient in a routine preoperative manner. The effect of the 3D models in altering the planned osteoplasty was then determined. Proportions of osteoplasty change were calculated at various positions, and categoric variables were assessed with the chi-square test for independence. RESULTS: Proportions of osteoplasty changes ranged from 20% to 55% at femoral positions (greatest at lateral and depth positions) and 35-75% at acetabular positions (greatest at anterior and depth positions). More osteoplasty changes occurred in patients with alpha angles of 60° or more (p = 0.00030) and without a radiographic crossover sign (p = 0.0075). We found no difference in the proportion of osteoplasty changes when stratifying by lateral center edge angle and coxa profunda (p = 0.190 and 0.109, respectively). The planned osteoplasty was changed for at least one reader in 9/10 (90%) femurs and 10/10 (100%) acetabula. CONCLUSION: Use of 3D models in preoperative planning can change both the extent and location of planned osteoplasty for FAI surgery and is particularly influential in patients with alpha angles of 60° or more and without a radiographic crossover.