Influence of pre-bending on primary fixation stability in one-segmental mandibular reconstruction

The fixation of osseous free flaps for segmental mandible reconstruction after resection is most commonly performed with patient-specific 3D printed or conventional load-bearing reconstruction plates. The main challenge with conventional plates is the step of manual bending to adjust the plate to the specific mandible of the patient. To date, the influence of this permanent plate deformation on the biomechanical conditions within the healing regions remains unknown. The present study aimed to investigate the effect of plate pre-bending on intersegmental strains, known to influence the healing outcome.

To achieve this, biomechanical finite element models were developed to simulate plate pre-bending and biting in a one-segmental mandibular reconstruction. The biomechanics induced within the healing region were compared between a pre-stressed conventional reconstruction plate and a customized conventional reconstruction plate.

Higher stresses were predicted in the pre-stressed plate. However, the mechanical strains within the healing regions were not influenced by plate pre-bending.

The increased levels of mechanical strains under both pre-stressed and customized conventional plates in comparison to common patient-specific plates could be a reason for the higher rates of osseous union under conventional fixation. Since customized conventional reconstruction plates additionally presented elastic stresses and include the advantages of patient-specific plates, those plates are biomechanically and clinically promising.