| Objective: To promote the blood supply of the free auricular composite graft and increase its survival rate,a modified method was used by enlarging the contact area between the auricular composite graft and the recipient site.The improvement and clinical application of free auricular composite graft were successfully explored for the repair of the alar defect.Methods:Experiment study:Twenty-one healthy New Zealand rabbits were involved in the study,and the animal model of auricular composite graft was designed as follows: Firstly,two 2 cm x 2 cm wounds were designed on the back of each animal,and the depth reach the subcutaneous tissue.Secondly,the auricular composite grafts of same size including two layers of skin sandwiching cartilage were cut from two ears of rabbit separately.Then,we cut the margin of the ventral side skin and cartilage of the graft in different size and kept the dorsal side skin complete.The residual ventral side skin was covered by a sterile sticker.Finally,the graft was transplanted to the wound on the back and was packaged for fixing.All grafts were randomly divided into 7 groups according to the different size of the reserved ventral side skin: Group 0cm,Group 1.0cm,Group1.4cm,Group 1.5cm,Group 1.6cm,Group 1.7cm,Group 2.0cm(for example,if the size of the reserved ventral side skin was 1.5cm×1.5cm,the graft would be assigned to Group 1.5cm).Six grafts were involved in each group.The package was taken off on the 7th day after surgery to observe the postoperative survival condition of the graft,and the specimen would be harvested for histological examination after two months of the operation.Clinical application:Five patients were involved.An arc incision line was marked by methylene blue above the residual rim of the defected ala nasi,and local anesthesia was performed by infiltrating 1% lidocaine.The skin and subcutaneous tissue below the incision line were separated and turned over 180 degrees to increase the blood supply of the recipient site.Then,a same-sized auricular composite graft was harvested from the superior pole of the opposite auricle.The donor site was primarily closed,and the upper crus of antihelix was reconstructed.Afterwards,trim the graft according to the already formed shape of the recipient site.Cut the conchal skin and cartilage partly to enlarge the blood contact area.At last,the transplantation was finished with 5-0#Prolene.Petrolatum gauze was packed into the nasal vestibule to stabilize the reconstructed ala nasi.Results:Experiment study:When taken off the package on the 7th day after surgery,all grafts stayed in place.No infection or hematoma happened.(1)Gross observation was conducted in the following days to evaluate their survival condition through indicators like color,shape,texture,etc.Group 1.0cm,Group 1.4cm and Group 1.5cm survived well,and the color was similar as the surrounding tissue.These three groups were names as “Complete survival group”.Group 1.6cm and Group 1.7cm showed necrosis in varying degrees in the middle of grafts,which were named as “Partial survive group”.Operation of grafts in Group 0cm were equal to skin grafting,and all grafts were totally survived.Group 0cm was considered as “Positive group”.Group 2.0cm all fell down during the following observation,which was considered as “Negative group”.(2)Histological observation was conducted with HE staining after 2 months of surgery.In complete survive group,the whole cartilage was in view;cartilage cells were arranged in order and showed good morphology.Cutaneous appendages were visible.While in partial survival group,cartilage was partly lost;chondrocytes around presented derangement distribution and cartilage lacuna disappeared;a large amount of collagen fibers and stromal responsive fibrosis could be observed.Calcification and degeneration of chondrocytes and inflammatory cell infiltration were also revealed.Clinical application:Five patients were underwent the modified auricular composite graft to repair the alar defects.The size of grafts ranged from 2.0cm×1.5cm to 3.0cm×2.0cm,and all patients were followed up for at least 8 months.Five grafts survived completely with brilliant color,contour and texture.One graft,the size of which was 2.0cm×1.5cm,showed partial necrosis and scar healing,considered caused by infection.Donor site morbidity is minimal,leading to high patient satisfaction.Conclusion: In animal experiment,when the kept ventral side skin was no more than 1.5cm×1.5cm,in another word,when the vascular contact area was no less than 43.75%,the auricular composite graft would survive completely,or it would show necrosis more or less.In clinical application,enlarging the vascular contact area between the graft and the recipient site is the key to promote its survive;when the area is no less than 50% of the graft,a large auricular composite graft can be successfully proceeded by the modified approach in our experience. |
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