MR-based 3D Models for SCFE Patients for Patient-specific Preoperative Planning of Modified Dunn Procedure or Hip Preservation Surgery: Feasibility Study

Purpose or Learning Objective: Slipped capital femoral epiphysis (SCFE) is a common pediatric hip disease. It is associated with the risk of disability, osteoarthritis, and impingement deformities. Three-dimensional (3D) magnetic resonance imaging (MRI) models would offer a radiation-free method for patient-specific preoperative planning. Therefore, we investigated the (1) feasibility of MRI-based 3D models of the hip; (2) feasibility of 3D printing and 3D impingement simulation using MRI-based 3D models; and (3) postoperative slip angle of symptomatic patients with SCFE.

Methods or Background: A retrospective radiographic study involving of 10 symptomatic patients (10 hips) with SCFE was performed. Mean age was 13 ± 2 years; 50% were male. Six patients had severe SCFE (four had moderate SCFE), and two patients had unstable SCFE. All patients underwent preoperative hip MR (2016–2019) with pelvic coronal high-resolution images (T1 volumetric interpolated breath-hold examination [VIBE] or T1 StarVIBE). Slice thickness was 0.8 to 1.2 mm. Semiautomatic MRI-based 3D segmentation was performed using AMIRA software. A 3D printing of 3D models was performed. The virtual 3D models were tested using specific software for dynamic 3D impingement simulation. All patients underwent open surgical treatment.

Results or Findings: (1) MRI-based 3D segmentation was feasible in all patients (100%; duration: 4.5 hours; mean: 277 ± 52 minutes). (2) The 3D printing of the hip 3D models was feasible in all patients (100%). The 3D models were considered helpful for preoperative planning of open hip preservation surgery by the treating surgeons. Dynamic 3D impingement simulation was feasible in six patients (six hips) and enabled visualization of femoral and acetabular impingement location. (3) Slip angle improved significantly (p < 0.001) from preoperative 54 ± 15 degrees (range: 40–70 degrees) to postoperative 4 ± 2 degrees (range: 2–10 degrees).

Conclusion: MRI-based 3D models of the hip for SCFE patients were feasible, and the postoperative radiographic outcome was good. The 3D models can be used for 3D printing and for impingement simulation. This technique could aid patient-specific preoperative planning and improve the understanding of this deformity. The 3D-printed MRI-based models are radiation free and could be used instead of 3D models based on computed tomography for the simulation of open hip preservation surgery (mock surgery), such as femoral osteotomy or the modified Dunn procedure.

 

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
02 June 2022