Minimal invasive surgery for maxillary transversal distraction osteogenesis with piezo-surgery device based on a 3D finite element analysis

Abstract

A new level of individual, highly standardized and more comfortable surgical interventions in CMF could be initiated by minimal invasive surgery based on 3D- finite element analysis. We evaluated the biomechanical effects of surgically assisted rapid maxillary expansion (SARME) by a bone anchored intraoral distraction device using a 3-dimensional FEM-model, whose construction was based on spiral computed tomographic (CT) scans of a 21-year-old woman. After evaluating the optimal areas for osteotomy, we used the modified technique in 19 patients. Finite Element Analysis (FEA) was created to depict the physiological changes and stress distribution in craniomaxillary bone complex. The distraction was performed on the middle intersection line of maxillary symphysis, the maxillary buttress and the pterygomaxillary sutures in variable extent. The mechanical response in terms of displacement and von Mises stresses was determined by widening the maxilla with a transpalatinal distractor (TPD). The stresses were simulated and analyzed using the patient's CT scan. We transferred our results to the Operation Room and performed the osteotomy with a piezo-surgery device. All of the 19 patients were evaluated regarding expansion diameter, intervention time, swelling, and infections. Generally high stress levels were observed in the FEA under the basal plates of distractor, in paranasal, zygomaticoalveolar and pterygomaxillary area. Only one patient showed an infection after surgical intervention, one patient was observed with an asymmetrical expansion. The intervention time we evaluate with about 39 minutes. Five days after the surgical procedure the swelling has resolved. With 3D analyzing of CT-scans there is a valid possibility to recognize individual stress distributions in SARME patients using TPD. Extent of osteotomy is individual and depends on stress levels of connecting bone structures. Using FEA and piezo-surgery we could perform the surgical procedure minimally invasive with reduction of patients side effects.