Use of Custom Three-Dimensionally Printed Models Improves Cam Resection Quality in Arthroscopic Treatment of Femoral Acetabular Impingement Syndrome.

/Objectives: To investigate whether the use of a three-dimensionally (3D) printed model, compared to conventional imaging, resulted in better corrections of osseous deformities following femoral acetabular impingement syndrome (FAIS) hip arthroscopy by comparing radiographic outcomes. A retrospective review of patients who underwent hip arthroscopy for FAIS between 2015 and 2019 was performed. Patients were sequentially allocated into the conventional or 3D model group. Radiographic plain films pre- and postoperatively assessed bony resection quality, measuring alpha angles and head neck offset (HNO) ratios using 45° Dunn, frog-leg lateral, and anteroposterior (AP) views. Good resection was defined as an alpha angle <55°, and poor resection as an alpha angle ≥55°. One-hundred forty-eight patients were included (n=86 in the conventional group, n=62 in the 3D model group). Compared to conventional imaging, the 3D model group had statistically significantly lower post-operative alpha angles on 45° Dunn (p=0.002) and frog-leg lateral views (p<0.001). The change (pre- to postoperative) in alpha angle was statistically significantly larger for the 3D model group, compared to conventional imaging, in 45° Dunn (p=0.003) and frog-leg lateral views (p=0.041). Compared to the conventional imaging group, the postoperative HNO ratio was statistically significantly higher in the 3D model group on 45° Dunn (p=0.001) and frog-leg lateral views (p<0.001) and change in HNO ratio was statistically significantly larger for the 3D model group in both 45° Dunn (p=0.001) and frog-leg lateral views (p=0.026). When considering the good and poor resections separately for all three radiographic views, the 3D model group showed a statistically significantly higher number of good resections than the conventional imaging group (p<0.001). Arthroscopic FAIS treatment shows adequate resection using conventional surgical planning. The use of a 3D model facilitated better cam resection and permitted more patients to return to within normal radiological values as measured by alpha angle and HNO ratios. III. (Retrospective Cohort).