Finite Element Evaluation of Different Osteosynthesis Variations That Used After Segmental Mandibular Resection

Computational models and their applications in biomechanical analysis of mandibular reconstruction surgery

Advanced head and neck cancers involving the mandible often require surgical removal of the diseased parts and replacement with donor bone or prosthesis to recreate the form and function of the premorbid mandible. The degree to which this reconstruction successfully replicates key geometric features of the original bone critically affects the cosmetic and functional outcomes of speaking, chewing, and breathing. With advancements in computational power, biomechanical modeling has emerged as a prevalent tool for predicting the functional outcomes of the masticatory system and evaluating the effectiveness of reconstruction procedures in patients undergoing mandibular reconstruction surgery. These models offer cost-effective and patient-specific treatment tailored to the needs of individuals. To underscore the significance of biomechanical modeling, we conducted a review of 66 studies that utilized computational models in the biomechanical analysis of mandibular reconstruction surgery. The majority of these studies employed finite element method (FEM) in their approach; therefore, a detailed investigation of FEM has also been provided. Additionally, we categorized these studies based on the main components analyzed, including bone flaps, plates/screws, and prostheses, as well as their design and material composition.

Comparison of locking and non-locking reconstruction plate-screw system in lateral mandibular defects by finite element analysis

PURPOSE

The purpose of this study is to analyze and compare stress distribution on bone screws and plate systems in locking and non-locking screw-plates design in lateral mandibular defects.

MATERIAL AND METHODS

Solid mathematical model of mandible was created by three-dimensional finite elements analysis and 25 mm length of lateral resection (L defect) was performed on the model. Models were reconstructed with 2.4 locking and non-locking reconstruction plate system. Each masticator muscles attached to mandible were simulated as direction, attachment area and magnitude on 3D model to compare with reality. The stress formation on bone and hardware system were evaluated.

RESULT

The stress values on the cortical bone, plate and screw system were higher in conventional plate model than the locking system model. The highest stress values were measured in the proximal segment especially in conjunction with conventional screw system. Furthermore, the distribution of stress on the bone surface was more homogenous in the locking system.

CONCLUSION

It is evident that the use of the locking system in 25 mm length lateral mandibular defects provides an additional advantage over conventional systems in reconstruction models.

Finite element analysis of stress distribution on reconstructed mandibular models for autogenous bone grafts

BACKGROUND

There are several challenges in terms of mandibular reconstruction. The defect size, graft materials, and plate combinations should be taken into consideration in surgical planning.

OBJECTIVE

The aim of this study was to evaluate the effect of different reconstruction variations on the stress distribution of segmental resected mandibles with two different defect sizes using finite element analysis (FEA).

METHODS

Computerized tomography images of a human mandible, fibula, and iliac crest were used as references to build three-dimensional (3D) models on a PC. The virtual plates and screws were used to simulate reconstruction of the mandibular defects. The models were divided into two groups based on the longitudinal defect size. Different osteosynthesis variations and autogenous graft material combinations were used to reconstruct the mandibles.

RESULTS

In all models, higher von Mises stress values occurred on the mandibles reconstructed with the fibula than those with the iliac crest. Fixation of the bone grafts with a reconstruction plate for the 10-mm defects and using a mini-plate in addition to the reconstruction plate for the 30-mm defects decreased stresses on the grafted bones.

CONCLUSIONS

Mandibular reconstruction with the iliac grafts is biomechanically superior to that with the fibular grafts. In addition, osteosynthesis methods and the defect size affect the stress distribution.