Study of fixation of a mandibular plate for favourable fractures of the mandibular angle: numerical predictions

Mandibular Titanium Miniplates Change the Biomechanical Behaviour of the Mandible in the Case of Facial Trauma: A Three-Dimensional Finite Element Analysis

Our study aimed to compare the biomechanical behaviour of mandibles with or without titanium miniplates when subjected to an impact after bone healing using a finite element model (FEM) of the human mandible. We simulated mandibular trauma on an FEM of a human mandible carrying or not two parasymphyseal miniplates and applying a concentrated force of 2000 N to four different areas, including the insertion area, the area straddling the edge of the miniplates and the adjacent bone, at a distance from the miniplates on the symphysis, and on the basilar border of the mandible below the miniplates. Then, we compared the Von Mises stress distributions between the two models. In the case of an impact on the miniplates, the maximum Von Mises stress occurred in two specific areas, on the cortical bone at the posterior border of the two miniplates at a distance from the impact, while in the model without miniplates, the Von Mises stresses were homogenously distributed in the impact area. The presence of titanium miniplates in the case of trauma affects the biomechanical behaviour of the mandible and could cause more complex fractures. We recommend informing patients of this potential risk.

Is Screw-Fracture Proximity or Residual Fracture Displacement Correlated to Outcomes After Open Reduction and Internal Fixation of Mandibular Angle Fractures?

PURPOSE

Computed tomography (CT) imaging is commonly obtained following open reduction and internal fixation (ORIF) of mandibular fractures but the significance of common findings is unknown. The purpose of this study is to examine the relationship of screw-to-fracture proximity and residual fracture displacement to post-operative complications following ORIF of mandibular angle fractures treated with monocortical fixation techniques.

METHODS

The authors conducted a retrospective cohort study consisting of all patients with mandibular angle fractures treated with ORIF using monocortical fixation at the lateral surface of the mandible from the dates August 1, 2015 to May 31, 2020. The predictor variables were the distance measurements between the 2 closest screws to the fracture and the fracture line and the amount of residual fracture displacement, both measured on post-operative CT. The primary outcome variable was the presence of postoperative inflammatory complications (POICs). Statistical analysis was performed using logistic regression and Bayesian variable selection to calculate posterior probability of importance for the variables of interest.

RESULTS

Of the 285 patients included in the study, 84.6% were men and the average age was 30.8 years. POICs occurred in 22.1% of the patients. Age, smoking, homelessness, noncompliance and drug use were associated with POICs. However, none of the screw-to-fracture distances were associated with POICs, including linear, dichotomous or polynomial transformations of these variables. Additionally, the residual fracture displacement distances and transformations of these distances were also not associated with POICs.

CONCLUSION

The present study did not find any evidence to suggest that a closer screw-fracture distance or increased residual fracture displacement on postoperative CT imaging increased the risk of POICs for mandibular angle fractures treated with ORIF using monocortical fixation at the lateral border.

Treatment of Mandible Fractures Using a Miniplate System: A Retrospective Analysis

Three-dimensional (3D) mini plate systems are used in the treatment of mandibular fractures. The system is advantageous in comparison to conventional plates due to the stabilization of tension and compression areas, improved initial stability, and biomechanical behavior. The aim of this retrospective study was to evaluate the use of a 3D miniplate system for the treatment of patients with mandibular fractures. Patients with mandibular fractures treated with a 3D plate system at the Department of Oral and Maxillofacial Surgery, University Hospital Münster, during a period of 5 years, were included in this study. Mandibular fracture conditions and minor and major post-operative complications were reported. In total, 336 patients and 391 mandibular fractures were assessed. The most common fracture site was anterior mandible, and 155 cases involved a tooth-bearing area. Minor complications were seen in 8.03% of cases, whereas only 1.49% of patients suffered from major complications. The treatment of mandible fractures using 3D miniplates resulted in fracture reduction with a low complication rate.