Accuracy of intertrochanteric osteotomy for patients with slipped capital femoral epiphysis operated with 3D printed patient-specific guides.

Background: Slipped Capital Femoral Epiphysis (SCFE), is one of the most common hip disorders in adolescents, and is treated surgically by performing an Imhäuser osteotomy. The use of 3D printed guides has shown promise in improving the accuracy of the osteotomy. However, misplacement of the guide may limit the improvement. Therefore, the aim of this study was to investigate, postoperatively, the degree of malalignment of 3D printed guides compared to the 3D planning.

Methods: Patients who underwent surgery between April 2018 and October 2022 and underwent postoperative CT were included in this study. The preoperative CT was used for 3D planning of surgical treatment using 3D printed patient-specific guides and plates. The positioning error of the femoral head and of the patient-specific guide and plate was quantified by analysing the postoperative CT scans using custom software.

Results: Five SCFE patients were included in the study. Femoral head malalignment improved from 16 to 40 mm preoperatively to 11-17 mm postoperatively. Rotational malalignment improved from 29-63⁰ preoperatively to 15-31⁰ postoperatively. Residual error was mostly attributed to plate malposition, with residual translation in the range of 3-13 mm and rotation of 8-28⁰.

Conclusion: Although the postoperative position improved after surgery with 3D printed surgical guides and plates, there was a residual deviation from the planned position persisted. Further research is recommended to improve the design, accuracy of guide placement and surgery in this anatomically challenging region.