Clinical Study Of Digital Surgery And Distraction Osteogenesis Techniques For The Treatment Of Hemifacial Microsomia

Objective1Set up three-dimensional coordinate system of hemifacial microsomia (HFM)patients with three-dimensional CT (3DCT)imaging model. Analyze and measure the deformities of facial asymmetry.Designing preoperative scheme of distraction osteogenesis.2Use rapid prototyping technique designs operative guide,accurately guiding mandiblular distractor implantation of hemifacial microsomia patients.3Measure and statistically analyze the three-dimensional CT data of hemifacial microsomia before mandibular distractor implantation and after distractor removed,assessment the results of operations, improved surgical approach.Study object and MethodsStudy object12HFM patients treated in Plastic Surgery Hospital,Chinese Academy of Medical Sciences Centre, Maxillofacial Plastic Surgery from August2009to June2011were selected in the study.Methods1Input HFM patient’s three-dimensional CT model data to medical software, calculating the mirro model data, and then input the two model data into industrial design software,looking for the best fitting plane,defining which as the symmytrical plane.Set the symmetrical plane as the median sagittal plane, then reset the three-dimensional coordinate system. Mark the anatomical landmarks,which should be accurate measured and analyzed in order to decide asymmetrical composition. Accurately design the position and orientation of distractor follow the results of measurement and analysis.2Input patient’s three-dimensional CT model data to medical software.Reconstruct the inferior alveolar neurovascular bundle, tooth etc, and then mark them at the outer cortex of mandible.Input all the data into industrial design software, and accurately design the osteotomy scheme.Desiged surgical guide using RP technology, guiding accurate designed osteotomy surgery. Unite preoperative design ideas and surgical procedures,simplifying surgical difficulty..reducing the risk of accidental injuries, reducing operation time and improving surgical results.3Input patient’s three-dimensional CT model data to industrial design software, and reset the three-dimensional coordinate system. Import postoperative three-dimensional CT model data,exact matching the preoperative data in order to unite them in the same three-dimensional coordinate system.Measure three-dimensional coordinate values of anatomical landmarks before and after the distraction osteogenisis, and calculate coordinates changes of skull anatomical landmarks, length, angle and anatomical plane.Results1After three-dimensional coordinate system was resetted, after accurate measured、analyzed and designed data of preoperation,12cases of hemifacial microsomia patients successfully completed mandibular distraction osteogenesis.2Through using RP technique to produce digital guide of mandibular osteogenesis, surgical operation and preoperative design was well fitted. We realized the surgical design procedure perfectly, improving surgical precision and security.2patients had severe dysplasia on mandibular ramus, by accurate preoperation design and using surgical guide, had avoided the mandibular ramus reconstruction surgery, and the distraction process went smoothly.3We measured6cases of hemifacial microsomia preoperation and postoperation three-dimensional CT data, and conducted a statistical analysis of some data. Measurement results confirmed that under the guidance of digital technology,mandibular distraction osteogenesis results were satisfactory. Data analysis confirmed that children in mixed dentition period have great growth potential on maxilla and zygoma.Distracition osteogenesis in this period can effectively reduce the operation times and the complexity of the surgery.ConclusionIn this experiment we used digital surgery techniques for treatment of hemifacial microsomia patients.By preoperative measurement and analysis, dedign the best surgery program, and using RP technique to produce digital guide of mandibular osteogenesis, surgical operation and preoperative design was well fitted, we realized the surgical design procedure perfectly, improving surgical precision and security. We also measured6patients with preoperative and postoperative three-dimensional CT data, confirmed that children in mixed dentition period have great growth potential on maxilla and zygoma.Distracition osteogenesis in this period can effectively reduce the operation times and the complexity of the surgery. Mixed dentition period is the best timing of mandibular distraction osteogenesis.