Nasomaxillary Rotation Centers in LeForte Osteotomies: 3D Finite Element Biomechanics

Objectives: T Objectives: This study aimed to precisely determine the 3D rotational centers in maxillary distraction osteogenesis across LeFort I-III osteotomies and evaluate how callus stiffness and soft tissue constraints influence segment mobility - critical factors for improving surgical accuracy. Materials and Methods: Using MSC.Marc/Mentat 2015, we developed patient-specific finite element models from high-resolution CT data, incorporating cortical/cancellous bone, dentition, and soft tissues. Three osteotomy models were analyzed under varying conditions: callus stiffness (10 MPa vs 500 MPa) and soft tissue contact (normal/none/full). Precise rotational centers were calculated by tracking 3D displacement vectors during 0.5 mm distraction increments. Results: The methodology successfully identified exact rotational centers (LeFort I: 8.2±0.3 mm; LeFort II: 10.1±0.4 mm; LeFort III: 11.8±0.5 mm superior to Frankfurt plane). These locations proved crucial for: (1) optimizing distractor positioning, (2) predicting rotation patterns, and (3) preventing malocclusion. The 500 MPa callus showed 38% greater deviation than 10 MPa, while LeFort III displacements increased 22% due to larger contact surfaces. Although 68% of movement occurred sagittally, significant transverse (19%) and coronal (13%) rotations were observed - findings that would be missed without 3D analysis. Conclusions: Precise rotational center determination is achievable through computational modeling and essential for successful distraction. The results challenge traditional 2D planning approaches. Clinical Relevance: This study provides surgeons with: (1) level-specific rotational center data, (2) callus maturation guidelines, and (3) 3D movement predictions - enabling personalized surgical planning to reduce complications.