Endoscopically Assisted Prominent Mandibular Angle Simulating Contouring Surgery With Postauricular Incision And Some Anatomical Study About The Operation

Background:In the east,the people who had square face,because of prominent mandibular angle were very common.It didn't fit the beauty standard of the people,who thinked that the oval-shaped face was beautiful. Nearly, As the improving of the people's material and cultural living standards, there were more and more people had come to do the plasty operation to change the facial contour for the purpose of beauty.There were many researches about this in the world.To the approach for prominent mandibular angle plastic surgery,there were intraoral approach,extraoral approach and combined intraoral, extraoral approach.Each approach had its own advantages and disadvantages.The intraoral approach was used widely now,but it had the disadvantages such as,the requiring for instrument was high,to control the scope of osteotomy was not easy,the possibility of oral cavity infection and the inconvenience after the operation.So there were people who didn't want to do the operation with intraoral approach for those reasons.When the people want to do both the face lifting and the prominent mandibular angle contouring surgery on the same time,the postauricular incision approach was suitable.During the last centuries,the techniques and clinical applicaton of endscope have enjoyed great development.It was used for clinical diagnose in the first time,then used in a lot of regions of clinical operations.The endscope was used in the operation on the body where it had nature celom generally, such as operation on oarium,gallbladder,colon and so on. Endoscopically assisted prominent mandibular angle contouring surgery with intraoral approach was used widely.Some doctors did prominent mandibular angle contouring surgery with postauricular minimal incision and achieved satisfactory results.nearly,but it did with bad visual fields,the opportunity to hurt the normal tissues was existed.There were many anatomy studies about the operation,but for the endoscopically assisted prominent mandibular angle contouring surgery with postauricular incision was absence.When did the operations with postauricular minimal incision,the branches of the great auricular nerve were very easy to be hurted. As the great cutaneous nerve of the cervical plexus, the great auricular nerve(GAN) was used for the neural transplantation donors,such as it was used for repairing the facial never injury.The shalloe section of the GAN is traveling steadily.It is covered by platysma,behind the external jugular vein,above the sternomastoid muscle and it is easy to hurt during the operation.The early researchs were focus on the nerve trunk of the great cutaneous nerve and little about the branches of the nerve.Some doctors suggested to study and protect the branches of the great cutaneous nerve,because the injury to the GAN would lead to some sensory losses,especialy the posterio branches.It would not take a long time to protect the branches during the operations. Objective:1.To do the anatomy research with the tissues about the mandibular angle aimed at the purpose to operate endoscopically assisted prominent mandibular angle contouring surgery with postauricular minimal incision.2. Try to operate endoscopically assisted prominent mandibular angle contouring surgery with postauricular minimal incision on the cadavers,to make sure the feasibility,to observe the anatomy structures through the endoscope.Methods:1. The clinical anatomical study to the endoscopically assisted prominent mandibular angle contouring surgery with postauricular incision.15 cadavers(6 females,9 males) offered by Department of anatomy,School of basic medical sciences,Southern medical university were used in the study.Instument:scalpel,scissors,forceps,binocular microscopes,digital camera, digital vernier,protractor.With neck specimens, detailed dissected from shallow to deep-level according to the original anatomy, to observe important anatomical structures from the postauricular incision to the mandibular angle, and the appropriate approach of the regional level. To measure the distance between root of the ear to the mandibular angle vertices, distance between facial lower buccal nerves and marginal mandibular branch at the masseter muscle trailing edge.To study the point where the great cutaneous nerve emerges from sternomastoid muscle,it's traveling line,the relationship with the external jugular vein, the branches's traveling line.To measure the length of the GAN trunk, the each length and width of the GAN's branches after the auricle, the distance from the point where the GAN divided into branches to the below end point of the auricle, the angle between the line 1 (from the point where the GAN divided into branches to the below end point of the auricle)and line2(the horizon line passing through the point where the GAN divided into branches), the distance from the points where the branches traveling into the auricle to the below end point of the auricle.The software Spass13.0 was used for data statistics.The Independent-sample T Test was used to analysis the datas.2. Endoscopically assisted prominent mandibular angle contouring surgery with postauricular incisionFive cadavers offered by Department of anatomy,School of basic medical sciences,Southern medical university were used in the study.Instument:Image acquisition system,PC monitor,luminescence source,endscopes(4cm×17cm,0°and 30°),eye scissors,periosteal strippings,bending forceps,and so on.The incision design and operation:Cut the skin with postauricular minimal incision,the incision's length was about 2cm,then separated the tissues bluntly with endoscope assisted.Through the endoscope assisted, the anatomical structures were observed on the PC monitor and the photos were taken.Results:1. After section of the skin,the branches of the great auricular nerve could be found easily. Separating the tissues bluntly with endoscope assisted, then to made a internal port with 2cm width.In some of cases,we could find the point where the great auricular nerve divide into 3 or more branches and the posterior auricular vein nearly during the oprations.Along the surface of the parotid gland fasciae to surface of the mandibular angle,we may find the retromandibular vein nearly in the area.Then incised the periosteum with sharp pointed scalpel and stripped the periosteum with periostotome. Then stripped the region where the masseter muscle stick to the mandibular angle.To make sure that the mandibular angle was exposed fully include superficial surface and deep surface of the angle, before cut the prominent mandibular angle.Then cut off some bone of the mandibular angle with the minimal saw.lt could be saw for a few times,for the operation field was limited. All these were done with endoscope assisted.2. The distance between root of the ear to the mandibular angle vertices was (3.45±0.50) cm in males,and (3.22±0.52) cm in females.There were two approach room for the operation, one was between the skin and the SMAS,another one was between the SMAS and masseteric fascia. The distance between facial lower buccal nerves and marginal mandibular branch at the masseter muscle trailing edge was (2.75±0.29) cm at left side of males, (2.82±0.28) cm at ringht side of males, (2.79±0.30) cm at left side of females, (2.83±0.28) cm at right side of females.The lower buccal branches,marginal mandibular branches, retromandibular vein,facial vein,facial artery was located in the masseteric fascia and was easily to hurt during the operation. The retromandibular vein was much close to the mandibular angle,the marginal mandibular branches were located one finger upper or inferior of the bottom edge of the mandibular.The great auricular nerve may originate from the anastomotic loop between the second and third cervica nerves, or directly from the latter.Immediately after its origin,it passes around the posterior margin of the sternocleidomastoid muscle and then proceed antero-superioly to parotid capsule and then divides into anterior and posterior terminal branches.In most of the cases, the GAN was about 10mm behind the external jugular vein.In few of the cases,the GAN was very closer to the external jugular vein. In most of the cases, the GAN was nealy above the posterior auricular vein,but the GAN winded around the posterior auricular vein In some of cases. The GAN divides into 3-4 branches in the plane of mandibular angle,those were called anterior auricular branch, lobe branch and posterior branch by some scholars.The anterior auricular branch spreaded into the skin(18sides,64%) or parotid(10sides,36%).There were three or more branches after the ear.In most of the cases,the first two branches had common trunk(23sides,82.1%).In some of the cases,the last two branches had common trunk.At one side there was four branches,each two had common trunk.In the left side,the middle length of the GAN trunk, length of the GAN's branches(NO1,NO2), the distance from the point where the GAN divided into branches to the below end point of the auricle after the auricle, and the width of NO3 GAN's branches had statistic difference between sex (P<0.05); In the right side, the length of the GAN's branches(NO2)and each of the distance from the points where the branches traveling into the auricle to the below end point of the auricle had statistic difference between sex (P<0.05).Conclusion:1.With endoscopically assisted,to do the prominent mandibular angle contouring surgery was practicable;The approach could from the space between skin and SMAS,or the space between SMAS and parotid gland fascia; Pay attention to the GAN's branches, marginal mandibular branches, retromandibular vein,facial vein,facial artery during the operation.2. The GAN has a constant traveling line and place.The relationship between the GAN and the external jugular vein was very close in some of the cases,which shoud arouse high attention by the operators.The study about the GAN branches would help the operators to design the postauricular incision,protect the GAN and it's branches during the operations. The GAN's branches could be the mark to the surgery approach space.3.It was a new and effective way to do the operation of endoscopically assisted prominent mandibular angle contouring surgery with postauricular minimal incision. The trauma was limited and the process was not complicated.During the operation,in order to prevent injury to the branches of the great auricular nerve, branches of the face nerve, and the retromandibular vein,the anatomical structures should be mastered.