MR-based Bony 3D models enable radiation-free preoperative patient-specific analysis and 3D printing for SCFE patients

Till D Lerch; Tilman Kaim; Valentin Grob; Markus Hanke; Florian Schmaranzer; Simon D Steppacher; Jasmin D Busch; Kai Ziebarth

doi:10.1177/18632521241229618

MR-based Bony 3D models enable radiation-free preoperative patient-specific analysis and 3D printing for SCFE patients

J Child Orthop. 2024 Feb 29;18(2):162-170. doi: 10.1177/18632521241229618. eCollection 2024 Apr.

Authors

Till D Lerch^{1

2}, Tilman Kaim^{1

3}, Valentin Grob¹, Markus Hanke⁴, Florian Schmaranzer¹, Simon D Steppacher⁴, Jasmin D Busch¹, Kai Ziebarth⁵

Affiliations

¹ Department of Diagnostic, Interventional and Paediatric Radiology, Inselspital, University of Bern, Bern, Switzerland.
² Department of Orthopaedic Surgery, Child and Young Adult Hip Preservation Program at Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
³ Graduate School for Health Sciences, University of Bern, Switzerland.
⁴ Department of Orthopedic Surgery, Inselspital, University of Bern, Bern, Switzerland.
⁵ Department of Pediatric Surgery, section of pediatric orthopedic surgery, Inselspital, University of Bern, Bern, Switzerland.

Abstract

Objectives: Slipped capital femoral epiphyses (SCFE) is a common pediatric hip disease with the risk of osteoarthritis and impingement deformities, and 3D models could be useful for patient-specific analysis. Therefore, magnetic resonance imaging (MRI) bone segmentation and feasibility of 3D printing and of 3D ROM simulation using MRI-based 3D models were investigated.

Methods: A retrospective study involving 22 symptomatic patients (22 hips) with SCFE was performed. All patients underwent preoperative hip MR with pelvic coronal high-resolution images (T1 images). Slice thickness was 0.8-1.2 mm. Mean age was 12 ± 2 years (59% male patients). All patients underwent surgical treatment. Semi-automatic MRI-based bone segmentation with manual corrections and 3D printing of plastic 3D models was performed. Virtual 3D models were tested for computer-assisted 3D ROM simulation of patients with knee images and were compared to asymptomatic contralateral hips with unilateral SCFE (15 hips, control group).

Results: MRI-based bone segmentation was feasible (all patients, 100%, in 4.5 h, mean 272 ± 52 min). Three-dimensional printing of plastic 3D models was feasible (all patients, 100%) and was considered helpful for deformity analysis by the treating surgeons for severe and moderate SCFE. Three-dimensional ROM simulation showed significantly (p < 0.001) decreased flexion (48 ± 40°) and IR in 90° of flexion (-14 ± 21°, IRF-90°) for severe SCFE patients with MRI compared to control group (122 ± 9° and 36 ± 11°). Slip angle improved significantly (p < 0.001) from preoperative 54 ± 15° to postoperative 4 ± 2°.

Conclusion: MRI-based 3D models were feasible for SCFE patients. Three-dimensional models could be useful for severe SCFE patients for preoperative 3D printing and deformity analysis and for ROM simulation. This could aid for patient-specific diagnosis, treatment decisions, and preoperative planning. MRI-based 3D models are radiation-free and could be used instead of CT-based 3D models in the future.

Keywords: 3D model; 3D printing; Slipped capital femoral epiphysis; in situ pinning.