Retrospective Study Of Mandibular Reconstruction Using Microvascularized Bone Flap And Condylar Displacement Post-operation

Objective: In the first section,cases of mandibular reconstruction using vascularized bone flap had been reviewed.Summing up the experience of mandibular reconstruction and evaluating the effectiveness and stability.The second section aims to measure the CT graphs of codylar displacement pre-and post-operation,research the impact of changes of jaw muscle attachment on condylar displacement after mandibular reconstruction.Methods: The first section of this research selected the continuous data in the oral maxillo-facial department from 2006 to 2017 in our hospital,and ultimately filtrated1038 cases of mandibular reconstruction using vascularized free bone flap.And then collected the pathological diagnosis,defect area,bone flap,selection of recipient artery and vein,post-operative complications,reconstructive method of the body of mandible and complications related to radiotherapy.In the second section,67 cases had been classified according to the attachment loss of jaw muscle,and then the CT image pre-and post-operation had been reviewed in Simplant software,bilateral condylar deflexion had been measured in cross sectional,sagittal and coronoid view;and condylar placement in three-dimensional view.Combined with the the follow-up of post-operation temporal-mandibular joint symptom,and then statistic analysis was performed with SPSS 22.0 software.Results: Among all the vascularized bone flaps,fibula flaps was the most commonly used(827/1038,79.67%),the second was circumflex iliac artery perforator(DCIA)flaps(197/1038,18.98%),and the last was scapula bone flaps(11/1038,1.06%).Among all the mandibular reconstruction cases,the mandible defects were most commonly leaded by ameloblastoma(366/1038,35.26%),followed by squamous cell carcinoma(278/1038,26.78%)and osteoradionecrosis(152/1038,14.64%);The first choice of recipient artery was the facial artery(596/1038,57.42%),followed by the superior thyroid artery(267/1038,25.72%);With regard to the recipient vein,the external jugular vein(447/1038,43.06%)and the common facial vein(263/1038,25.34%)were the most commonly used.Among all 1038 cases,68 patients(5.49%)had major complications requiring surgical intervention and one patient died of a pulmonary embolism.Venous crisis was the most frequent major complication(n =20,1.93%),followed by haematoma(n = 17,1.64%)and flap necrosis(n = 14,1.35%).In our research,the retention of coronoid process represented impact on rotating in coronoid view of contralateral condyle;cross-midline defect represented impact on rotating in cross-sectional view of bilateral condyle,moving in anterior-posterior and medial-lateral direction of ipsilateral condyle,moving in vertical direction of contralateral condyle;the total loss of unilateral ascending jaw muscles represented impact on rotating in cross-sectional view,moving in anterior-posterior and vertical direction of contralateral condyle,and the discrepancy above presented statistical significance(p<0.05).The groups of which coronoid process retention,across-midline defects and total loss of unilateral ascending jaw muscles presented relatively more severe temporal-mandibular joint symptom.Conclusions: The free vascularized bone flap should be considered as the reliable and effective choice for oromandibular reconstruction,particularly those with large bone defects requiring multiple osteotomies.The attachment loss of jaw muscle after mandibular reconstruction could lead to condylar displacement and impair the function of temporal-mandibular joint.