The Clinical Retrospective Analysis Of Different Types Of Vascularized Free Fibula Flaps For The Reconstruction Of Mandibular Defects

Background:The mandible,as the only movable bone in the lower 3^rd of face,is crucial for maintaining facial appearance,chewing,articulation and swallowing and airway patency.Oncologic surgical ablation is the main cause of mandibular defect,which seriously affects the facial appearance and quality of life of patients.The vascularized free fibular flap is the workhorse flap for repairing mandibular defects,its application can repair the continuity of the defected mandible,sometimes can also restore vertical height of the bone.Moreover,it can simultaneously reconstruct the complex defect of hard tissue and concomitant soft defects due to easy raise of skin island（s）.Objectives:To review different strategies of vascularized free fibular flaps（FFF）to reconstruct the soft and hard tissue defects of lower 3rd of face,aiming to compare the repair effect of FFF in restoring mandibular continuity and alveolar bone height.The second aim was to evaluate the diversity and flexibility of the FFF restoring the mandibular defects to summarize experience and provide guidance for clinicians.Methods:From March 2016 to January 2022,we recruited 38 patients who underwent segmental resection of the mandible due to benign or malignant tumors and immediately reconstructed with vascularized FFF The patients included 27 males and 11 females and aged range from 15 to 72（49.2±15.7）years old.The diseases included 11 cases of ameloblastomas,1 case of odontogenic keratocyst,17 cases of oral squamous cell carcinoma,6 cases of central carcinoma of the jaws,2 cases of oropharyngeal cancer and 1 case of adenoid cystic carcinoma.All resected tumors were confirmed by postoperative pathological examination.Preoperative design methods,mandibular defect types,different strategies of FFF application,types of harvested skin islands,and postoperative complications of recipient and donor sites were summerized and analyzed.The patients were followed up from 1 month to 2 years,panoramic radiographs were taken to examine the condition of implanted fibula and residual mandible.SPSS23.0 was used for statistical analysis,P<0.05 meant the difference was statistically significant.Results:1.Preoperative design methods:twenty-one cases were repaired and reconstructed under the auxiliary of model surgery and 3D printing before surgery,the average operation time was 9.61±1.51h.The reconstructions the rest of seventeen cases were facilitated by computer assisted surgery,with an average operation time of 8.95±1.16h,P<0.05,the difference was not statistically significant.2.Classification of mandibular defects:Functionally superior new classification of mandibular defects（COM）proposed by professor Zhang Chenping was employed,the defects of all cases were divided as below:1case of typeⅠb,21 cases of typeⅡb,and 3 cases of typeⅢb,2cases of typeⅡb-Ⅱb,1 case of typeⅡb2-1,4 cases of typeⅡb2-2,2 cases of typeⅡb2-Ⅰb2.According to the HCL classification method,there were 3 cases belonged to H defects,13 cases belonged to L defect,11 cases belonged to LC and 11 cases belonged to LCL.The length of mandibular defects were4.85-17cm,with the mean length of 8.29±2.69cm.3.For reconstruction methods of mandibular defects,twenty-eight cases were repaired with single-layer vascularized FFF,among which,in26 patients only the continuity of the mandibular lower margin were restored,whereas the height of alveolar process in the tooth bearing area was obviously insufficient.To avoid the insufficiency of the height of alveolar process in the tooth bearing area,one mandibular defect was repaired by placing the fibular flap at an alveolar bone position above the typical inferior mandibular border.In another case,interestingly,the fibula had enough width,reaching as high as 3/4 of the height of the mandible,therefore,single-barrel FFF restored the mandibular height to a great extent.Eight patients were repaired by vascularized double-barrel FFF,and 2patients were reconstructed using vascularized single-barrel FFF combined with free fibula graft,in which the mandibular continuity and alveolar bone height were successfully restored.4.In terms of vascularized FFF carried skin islands for the repair of combined soft tissue defects,there was 1 case without skin islands due to the absence of perforators of peroneal vessels,single skin island was used in 33 patients,and dual-skin islands were raised in 4 cases to restore complex defects.5.Postoperative complications at recipient and donor sites:All the vascularized FFFs except one were survived.In the recipient area,the incidence of vascular crisis was 7.9%,the incidence of flap necrosis was5.3%,the rate of secondary healing was 18.4%and the rate of primary healing was 81.6%.In donor site,the incidence of lower limb pain and edema was 13.2%and 5.3%,respectively.The rate of secondary healing was 5.3%and the rate of primary healing was 94.7%.Postoperative follow-up lasted from 1 month to 24 months.One patient suffered from mandibular osteomyelitis due to radiotherapy 6 months after operation,the rest of the patients recovered well.Conclusion:The application of vascularized FFF is flexible,vascularized FFF can not only restore the continuity of mandible,but also restore the height of mandible through various strategies to meet the needs of simultaneous or secondary implantation.In addition,vascularized FFF can carry single or dual-skin islands to restore complex soft tissue defects.