Stability of different fixation methods after reduction malarplasty under average and maximum masticatory forces: a...

Area of Science:

• Oral and Maxillofacial Surgery
• Biomechanical Engineering
• Craniofacial Reconstruction

Background:

• Titanium plates/screws are common fixation methods (FM) for L-shaped osteotomy reduction malarplasty (LORM), but optimal techniques remain debated.
• Finite element analysis (FEA) is employed to evaluate zygomatic complex stability under various fixation strategies.

Purpose of the Study:

• To investigate the biomechanical stability of different zygomatic body and zygomatic arch fixation combinations after virtual LORM.
• To analyze stress, strain, and displacement distribution using three-dimensional (3D) mapping.

Main Methods:

• A finite element analysis (FEA) model of the zygoma complex was created for virtual LORM.
• Various fixation methods (FM) for the zygomatic body and zygomatic arch were simulated under average (150 N/mm²) and maximum (750 N/mm²) forces.
• Stress, strain, and displacement were mapped in 3D across the zygomatic bone, fixation components, and the entire model.

Main Results:

• Fixation on the short arm of the L-shaped osteotomy demonstrated lower stress, strain, and displacement compared to the long arm.
• The two bicortical screws (2LS) group on the zygomatic body, combined with the Mortice-Tenon (MT) structure on the zygomatic arch, yielded minimal displacement and the lowest bone stress.
• Applied forces significantly impacted zygomatic bone stress and displacement (P < 0.001).

Conclusions:

• All evaluated fixation methods provide adequate zygomatic complex stability post-LORM.
• The 2LS fixation method exhibits superior resistance to stress concentrations compared to rectangular (RP) and square plates (SP).
• L-shaped plates with a short wing on the maxilla (LPwM) are more stable than those on the zygoma bone (LPwZ).