The Evaluation Of Comprehensive Treatment Of Adult Hemifacial Microsomia Based On The Digital Surgical Techniques

Objective:The major clinical manifestation of hemifacial microsomia (HFM) is the facial asymmetry that caused by the unilateral maxillary and mandibular dysplasia. Because of unknown etiology and controversial treatment timing,, the treatment plan of HFM is chaotic and nonstandard. The severe facial deformities of some HFM patients were not corrected properly in childhood. In order to normalize the treatment, we proposed a series of staging surgery treatment of the adult HFM based on the digital surgical techniques. To evaluate the surgical efficiency quantitatively, cephalometric analysis was conducted in all patients. The aim of this study was to evaluate the surgical effects of adult HFM which were treated with mandibular distraction osteogenesis combined with orthognathic surgery.Methods:18adult patients with HFM treated in Plastic Surgery Hospital, Chinese Academy of Medical Sciences Centre. Maxillofacial Plastic Surgery from September2009to March2014were selected in the study. The three-dimensional CT reconstruction data were used with Mimics software for preoperative simulation and design. The osteotomy location, distraction vector, distraction distance were decided before the operation. In the first stage, internal distractor was implanted after osteotomy through an extra-oral approach. The distractor was maintained for5-12months after distraction. In the second stage, Le Fort I osteotomy was performed in order to correct the cross-bite. In the meanwhile,a genioplasty and bone grating were performed if necessary for facial contour correction. In the third stage, autologous fat grafting was performed for facial contour reconstruction after5-12months later. Patients were randomly divided into experimental group and control group. The masseter multipoint injection with botulinum toxin A was performed on the second stage in experimental group.8cases with follow-up results (experimental group4cases, control group4cases) were selected to analyze the mandibular retraction rate. The three-dimensional CT data of three stages was input into the Proplan software to reconstruct. Through measuring the height of bilateral mandibular ramus. the horizontal interval between bilateral condyle, the distance from chin point to facial midline of pre-operation and post-operation,the changes of skull anatomical landmarks, lengths, angles and planes were analyzed.The asymmetric rate and retraction rate of mandibular ramus were calculated. The results were evaluated by statistical analysis.Results:Both the facial symmetry and occlusal relation of the18adult HFM patients were significantly improved after the comprehensive treatment, all the patients were satisfied. Without any complication to17cases, only1case suffered maxillary incision infection which was delayed union after debridement. There was no influence on the facial contour and occlusal relation. The measuring points in time of18HFM cases were pre-operation,5-12months after distraction,5-12months after the second stage. The mandibular ramus height of affected side rose by42.89+/-8.68mm to61.18+/-7.92mm. The asymmetric rate of bilateral mandibular ramus fell from32.56%to9.56%. The horizontal interval between bilateral condyle reduced from101.85+/-8.69mm to96.45+/-8.73mm. the distance from chin point to facial midline changed from13.62+/-4.23mm to4.23+/-2.71mm. Grouping antitheses was used in8cases, the retraction rate of experimental group with botulinum toxin A injection was16.31+/-6.06%. while the rate of control group was32.68+/-1.05%.Conclusion:Mandibular distraction osteogencsis combined with orthognathic surgery was an effective option for treatment of adult HFM..In this study we used digital surgical techniques for treatment of hemifacial microsomia. By preoperative measurement and analysis, design the best surgery program, guide the procedure using RP technique, ensure the operation is closely connected with preoperative design ideas. Comparing preoperative with postoperative measurements summarized that the comprehensive surgical treatment’s effect is remarkable. There was a recurrence of affected mandibular ramus with different degrees. This situation could be improved by the masseter injection with botulinum toxin A during the treatment process.