ORIGINAL ARTICLE
Experimental Study of Free Fat Grafts in Temporomandibular Joint Disc Anchor Pei Shen, MS, ShanYong Zhang, MD, Chi Yang, MD, and Liang Huo, MS Abstract: This study aims to evaluate the effect of using free fat grafts in preventing adhesion in the temporomandibular joint (TMJ) disc anchor and to observe the outcomes of free fat. Six 3-month-old mini-pigs were included in our study. The left joints were the experimental sides which had undergone releasing the anterior attachments, and free fat from the front of the ear lobe was grafted to the anterior gap. The right joints were the control group, where only the anterior attachments were released. MRIs were carried out and the maximal passive mouth openings were measured before operation, 3 months, and 6 months after operation. The joint tissues and fat specimens were excised after 3 and 6 months. The volume of fat was measured and hematoxylin and eosin (HE) staining was performed. Maximal passive mouth openings were analyzed with SPSS software package by Wilcoxon signed rank test. Maximal passive mouth openings were reduced gradually after 3 and 6 months, accompanied with the deviation of the mandible to the right side. There were significant differences between the 3 groups (P G 0.01). HE staining showed that the surface of the experimental joints was smooth while there was adhesion formation in the control joints. The volume of fat reduced respectively to 67.7% and to 42.6% after 3 and 6 months. HE staining showed new fat lobules were formed after 6 months with obvious fibrosis among the lobules. This study suggested that free fat can survive What Is This Box? A QR Code is a matrix barcode readable by QR scanners, mobile phones with cameras, and smartphones. The QR Code links to the online version of the article.
From the Department of Oral and Maxillofacial Surgery, Ninth People’s Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, People’s Republic of China. Received May 20, 2013. Accepted for publication September 17, 2013. Address correspondence and reprint requests to Dr ShanYong Zhang, Department of Oral and Maxillofacial Surgery, Ninth People’s Hospital, Collage of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai Research Institute of Stomatology, No. 639, Zhi Zao Ju Rd, 200011 Shanghai, People’s Republic of China; E-mail: [email protected] This study was supported by Shanghai Leading Academic Discipline Project (S30206), Natural Science Foundation of Shanghai Municipality (10ZR1418200), and Shanghai Pujiang Talent Plan in 2011, 2013 National Natural Science Foundation of China (81371168), Shanghai Science and Technology Commission (13XD1402300), the Seventh Students’ Innovative Training Project of Shanghai Jiaotong University School of Medicine (2013052). The authors report no conflicts of interest. Copyright * 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000419
The Journal of Craniofacial Surgery
steadily 6 months after operation, with a surviving volume about 42.6% and it can also prevent adhesion formation in the TMJ disc anchor. Key Words: Temporomandibular joint, disc anchor, free fat grafts, adhesion (J Craniofac Surg 2014;25: 253Y257)
T
emporomandibular joint (TMJ) anterior disc displacement without reduction (ADDwoR) is one of the most common TMJ disorders with an incidence of 26%.1 Arthroscopic operation or disc anchors are usually used to treat ADDwoR.2,3 However, in our clinical work, we found that about 3% of patients only treated by disc anchor had a recurrence of anterior disc displacement. For those patients, intra-articular adhesions and scar tissues at the site of the released anterior attachment were found when they underwent a second surgery. In order to reduce recurrence and adhesion, some studies4 reported that the injection of hyaluronic acid into TMJ cavity could reduce fibrous tissue proliferation. However, in the clinical work, because of the existence of gap after releasing the anterior attachments, surgeons usually choose free fat grafts to fill the joint cavity. Although different types of fat grafts have a certain application in TMJ surgery, such as buccal fat pad,5 abdominal dermis fat,6,7 and full-thickness skin subcutaneous fat,8 there have been no clinical and experimental studies to confirm its effect in preventing adhesion and reducing recurrence in TMJ anchor. Besides, the outcomes of free fat in TMJ surgery were not precisely defined. Although Dimitroulis et al9 concluded that non-vascularized fat grafts do not survive transplantation but stimulate neoadipogenesis by animal studies, they used abdominal dermis fat rather than free fat. Whether the outcomes of free fat grafts are the same as dermis fat is not sure. Therefore, we simulated the TMJ disc anchor to evaluate the effect of free fat grafts in preventing adhesion and reducing recurrence and its outcomes.
MATERIALS AND METHODS Experimental Animals and Surgical Technique Six healthy 3-month-old mini-pigs were provided by the Animal Experiment Laboratory of Shanghai Jiao Tong University School of Medicine. The selection standards of animals were as follows: 3 months old, weighing 15 to 17 kg, no teeth missing, good nutrition, and moving freely. The left TMJ was taken as the experimental side, while the right side was taken as the control side. The experimental animals were generally anesthetized using 2.5% amobarbital (1 mL/kg) by intravenous injection after ketamine (2 mL/5 kg) via intramuscular injection. The fur on the preauricular region was shaved and sterilization was performed afterward. Two percent lidocaine (1.5 mL) was injected locally. Preauricular incisions were conducted to expose the TMJ of the mini-pigs. The surface structure, including superficial temporal artery and veins, the parotid gland, and the facial nerve branches in this area, were pulled forward to avoid injury. The anterior attachments on the left joints
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FIGURE 1. The implantation process of a free fat to the temporomandibular joint. A, Incision of the surgery. B, Cutting the free subcutaneous fat in front of the ear lobe with the size about 15 mm 5 mm 5 mm. C, Placing the fat flap in the gap. D, Suture in layer.
were released and free fat from the front of ear lobe was grafted in the gap. The size of each fat was 15 mm 5 mm 5 mm. The right joints only had the anterior attachments released, without using free fat grafts. Three hundred twenty thousand units of penicillin was injected intramuscularly 2 times a day for 1 week after operation (Fig. 1).
MRI Examination MRI examination was carried out before, right after, 3 months after, and 6 months after operation. The scanner was a General Electric (Signa; General Electric, Milwaukee, WI) 3.0 T system with the ‘‘Excite’’ platform. Dual phased array dedicated TMJ surface coils were used before and right after operation, while body phased array coils were used after 3 and 6 months because of the growth of the mini-pigs.
Maximal Passive Mouth Opening Measurement The experimental animals were generally anesthetized using ketamine (2 mL/5 kg) via intramuscular injection before, 3 months, and 6 months after operation. A dedicated orthodontic micro-dynamometer was used to measure the distance between the upper and lower incisors as the maximal passive mouth openings. Each parameter was measured 3 times and a deviation of the mandible was observed.
Specimen Preparation and Histological Staining The experimental animals were killed after 3 and 6 months, and the articular cavity was dissected to observe whether there was adhesion formed. Then, the grafted free fat was cut to measure the volume with a 2-mL measuring cylinder. The joint and fat tissues were placed into a 4% formaldehyde solution for fixation. Conventional dehydrated paraffin embedment and serial sections were performed. HE staining was done for light microscope observation.
Statistical Analysis Differences between different times of maximal passive mouth openings were compared with the help of Wilcoxon signed rank test, using the Statistical Package for the Social Sciences (version 16.0; SPSS Inc., Chicago, IL).
RESULTS MRI Observation The radiological presence of grafted tissue was found in all 6 operated joints that were scanned with MRI. Right after the operation, the free fat was mainly of white appearance on the MRI
254
TI-weighted sequences. It gradually changed to off-white and gray after 3 and 6 months, accompanied with a decrease in size of the free fat (Fig. 2).
Maximal Passive Mouth Opening Findings The mandible of all mini-pigs deviated to the right side after 3 and 6 months. The data of maximal passive mouth openings are shown in Table 1. There were significant differences within preoperation, 3 months after, and 6 months postoperation (P G 0.01).
Gross and Histological Observation Gross observation of the specimens: there was obvious synovial hyperemia accompanied by tiny fibrous tissues in the articular cavity after 3 months and visible big cicatricle healing after 6 months on the control joints. Yet the surface of the experimental joints was smooth with no hyperemia or adhesion (Fig. 3). The average volume of the original fat grafts was 0.359 T 0.027 cm3 and it reduced respectively to 0.243 T 0.015 cm3 and 0.153 T 0.021 cm3 after 3 and 6 months, which was 67.7% and 42.6% of the original volume. Hematoxylin-eosin (HE) staining of the joint specimen: the surface of the synovium was neat and smooth in the experimental side. In the control side, there was a large amount of small blood vessel hyperplasia, accompanied with some fibrous tissue after 3 months. After 6 months, a large amount of fibrous tissue was seen in the control side with a few inflammatory cells. However, there was no adhesion formed in the experimental side except for the dilatation of a few vessels (Fig. 4). HE staining of the free fat flap specimen: normal adipose cells are round and slightly flat, arranged in nests or sheets. The nucleus size is consistent and the cell membrane is smooth, and a little of the fiber capsule encircles the fat tissue. However, a large number of plasmocytes and a few of macrophagocytes can be found in the grafts after 3 months. Fibrous septum in the grafts was increased accompanied with some new vessels. After 6 months, the inflammatory cells significantly reduced and some adipose cells clumped into fat lobules, which were close to normal fat tissue. Fat lobule fibrosis was obvious and spread over the grafts (Fig. 5).
DISCUSSION Autologous fat grafts have been used in surgery for over a century.10 Because of their richness, easy material availability, simple operation, and lack of rejection, autologous fat grafts have * 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery
& Volume 25, Number 1, January 2014
Free Fat Grafts in TMJ
FIGURE 2. Images of the free fat on MRI. A, The image of TMJ on the MRI before operation. B, The free fat was observed on the MRI right after operation (red arrow). C, The free fat was observed on the MRI 3 months after operation (red arrow). The signal was decreased and the volume was reduced. D, The free fat was observed on the MRI 6 months after operation (red arrow). The signal was decreased and the volume was reduced further.
drawn much attention from cosmetic and oral and maxillofacial surgeons.11 At present, autologous fat grafts have mainly been used in the following fields12Y16: (1) cosmetic repair, such as breast implants, facial fillers, wrinkle removals, repair of scar concave, as well as youth objectives during the period of aging; and (2) reconstructive repair, including tissue depression after trauma or operation, some congenital malformation and ocular socket plasty, and so on. Autologous fat grafts have achieved positive clinical effects in these fields. In TMJ surgery, dermis-fat grafts were first introduced by Georgiade in 1957 as an interpositional graft in the management of TMJ ankylosis.17 Since then, more and more attention has been paid to the use of fat grafts in this field. Besides TMJ ankylosis, autologous fat grafts were also used for disc repair or as disc replacement material following discectomy.18Y20 Candirli et al18 reported that those who underwent autogenous dermis-fat grafts as disc replacement material following discectomy showed improvement in both mandibular mobility and function 1 year after operation. Dimitroulis et al9,21 confirmed that abdominal dermis-fat grafts could inhibit the growth of new bone and cartilage in both clinical and experimental studies. However, these studies were all about dermis-fat grafts and there is no literature about whether free fat grafts could prevent adhesion and relapse of the disc anchor. In the present study, maximal passive mouth openings were reduced gradually after 3 and 6 months, accompanied by the deviation of the mandible to the right side. This indicated that the function of the right joints was damaged and the joint dysfunction was more serious after 6 months. Gross observation of the control joints showed that
there was obvious synovial hyperemia after 3 months. Accordingly, there was some fibrous tissue in the control joints shown in HE staining. This prompted the conclusion that initial adhesion tissue had formed. Meanwhile, hyperplasia and the dilatation of small blood vessels in the control joints suggested that these blood vessels could continuously provide nutrition for the growth of adhesion tissue. After 6 months, there was a large adhesion under gross observation in the control joints. This was consistent with the results of HE staining that mature fibrosis tissue with fewer blood vessels was observed under the light microscope. Conversely, the joint surface was smooth with
TABLE 1. Maximal Passive Mouth Opening (MPMO) and Deviation of Mandible Before Operation, 3 Months, and 6 Months After Operation (mm) 3 Months After Operation
Before Operation Number 1 2 3 4 5 6
MPMO 65 59 59 62 60 62
T 1.15 T 1.00 T 0.57 T 1.53 T 1.53 T 2.08
Deviation Vertical Vertical Vertical Vertical Vertical Vertical
MPMO* 51 57 51 55 53 52
T T T T T T
2.00 1.53 1.15 1.53 1.00 2.00
6 Months After Operation
Deviation
MPMO**
Deviation
Right Right Right Right Right Right
52 T 1.15 49 T 2.00 47 T 1.53
Right Right Right
*Comparison between preoperation and 3 months after operation, P G 0.001. **Comparison between 3 months and 6 months after operation, P G 0.01.
* 2014 Mutaz B. Habal, MD
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FIGURE 3. The joint gross specimens after operation. A, The surface of the control side joint was characterized by obvious hyperemia and tiny fibrous tissue (arrow) 3 months after operation. B, The surface of the experimental side joint was smooth, without hyperemia or fibrous tissue (arrow) 3 months after operation. C, Adhesions were formed in the control side joint (arrow) 6 months after operation. D, There was no adhesion in the experimental side joint (arrow) 6 months after operation.
no hyperemia or adhesion occurring after 3 and 6 months. Besides, the grafted free fat was connected to the front of the disc, which increased the length of the disc and prevented the formation of cicatricial healing. These results suggest that free fat can block fibrosis formation and reduce recurrence of disc displacement. Although fat grafts were widely used in surgery, there were different results in the volume change of grafted free, and the loss in volume of grafted fat ranged from 20% to 70% in literature.22,23 In the present study, the volume of grafted fat was reduced respectively to 67.7% and 42.6% after 3 and 6 months. This was in accordance with the results reported by Konanas.23 The reason might be that the form of fat grafts in the 2 studies is the same. Both Konanas
and we used block transplantation, which had the advantages of maintaining normal tissue structure and reducing the destruction of preadipocytes. There are some factors affecting the survival of grafted fat and the most important factors are the form of grafts and the blood supply in the receptor region.22,24 In our study, we used block transplantation which is conducive to establishing blood circulation between the grafts and the receptor region, as well as promoting the maturity of preadipocytes. As a result, block transplantation might be useful for the survival of grafted fat. MRI was also used to evaluate the radiological changes of the free fat in this study. The signal intensity of the grafted fat gradually weakened after operation, which changed from white to off-white
FIGURE 4. Histological observation after joint operation (original magnification 200). A, Hematoxylin and eosin staining of the experimental joint 3 months after operation. The surface of the synovium was smooth. B, Hematoxylin and eosin staining of the control joint 3 months after operation. A large number of small blood vessels were seen in the synovium (arrow) and there was some tiny fibrous tissue above the synovial surface. C, Hematoxylin and eosin staining of the experimental joint 6 months after operation. The surface of the synovium was smooth with a few small vessels. D, Hematoxylin and eosin staining of the control joint 6 months after operation. A large amount of dense fibrous tissue was observed with some inflammatory cells (arrow).
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* 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery
& Volume 25, Number 1, January 2014
Free Fat Grafts in TMJ
FIGURE 5. Histological observation of the free fat (original magnification 100). A, Hematoxylin and eosin staining of a normal subcutaneous fat in the front of the ear lobe. B, Hematoxylin and eosin staining of the free fat 3 months after operation. Small blood vessels were proliferated (red arrow) and macrophagocytes were seen (green arrow). C, Hematoxylin and eosin staining of the free fat 6 months after operation. New fat lobules were formed and interlobular fibrosis was apparent, between which cyst changes were seen.
and gray. This suggested that the components of free fat had been changed and it was confirmed through histological observation. HE staining showed that the grafts were in chronic inflammation as there were a lot of plasmocytes and a few macrophagocytes accompanied by the growth of fibrosis after 3 months. After 6 months, the chronic inflammatory cells significantly reduced and fibrosis was obvious in the fat lobules. Because the signal intensity of fibrosis is lower than fat in MRI, this might result in reduction of signal intensity. Also, some adipose cells clumped into fat lobules, which were close to normal fat tissue. It concluded that the grafted fat survived steadily after 6 months. In a word, we can draw the following conclusions: (1) Free fat can partly survive after 6 months in TMJ disc anchors, with the surviving volume about 42.6%. (2)The use of free fat grafts can also prevent adhesion formation and reduce the recurrence in TMJ disc anchor.
REFERENCES 1. Milano V, Desiate A, Bellino R, et al. Magnetic resonance imaging of temporomandibular disorders: classification, prevalence and interpretation of disc displacement and deformation. Dentomaxillofac Radiol 2000;29:352Y361 2. Zhang S, Liu X, Yang X, et al. Temporomandibular joint disc repositioning using bone anchors: an immediate post surgical evaluation by magnetic resonance imaging. BMC Musculoskelet Disord 2010;11:262 3. Currie R. Arthroscopy for treating temporomandibular joint disorders. Evid Based Dent 2011;12:90Y91 4. El-Hakim IE, Elyamani AO. Preliminary evaluation of histological changes found in a mechanical arthropatic temporomandibular joint (TMJ) exposed to an intra-articular hyaluronic acid (HA) injection, in a rat model. J Craniomaxillofac Surg 2011;39:610Y614 5. Singh V, Dhingra R, Bhagol A. Prospective analysis of temporomandibular joint reconstruction in ankylosis with sternoclavicular graft and buccal fat pad lining. J Oral Maxillofac Surg 2012;70:997Y1006 6. Dimitroulis G. Macroscopic and histologic analysis of abdominal dermis-fat grafts retrieved from human temporomandibular joints. J Oral Maxillofac Surg 2011;69:2329Y2333 7. Dimitroulis G. Condylar morphology after temporomandibular joint discectomy with interpositional abdominal dermis-fat graft. J Oral Maxillofac Surg 2011;69:439Y446 8. Thangavelu A, Santhosh Kumar K, Vaidhyanathan A, et al. Versatility of full thickness skin-subcutaneous fat grafts as interpositional material in the management of temporomandibular joint ankylosis. Int J Oral Maxillofac Surg 2011;40:50Y56
9. Dimitroulis G, Slavin J, Morrison W. Histological fate of abdominal dermis-fat grafts implanted in the temporomandibular joint of the rabbit following condylectomy. Int J Oral Maxillofac Surg 2011;40:177Y183 10. Billings E Jr, May JW Jr. Historical review and present status of free fat graft autotransplantation in plastic and reconstructive surgery. Plast Reconstr Surg 1989;83:368Y381 11. Tucker MR. Dermal graft harvest technique for use in temporomandibular joint disc repair. J Oral Maxillofac Surg 1989;47: 1116Y1118 12. Mori K, Ohta K, Nagano S, et al. [A case of ophthalmic artery obstruction following autologous fat injection in the glabellar area]. Nihon Ganka Gakkai Zasshi 2007;111:22Y25 13. Chaput B, Foucras L, Le Guellec S, et al. Recurrence of an invasive ductal breast carcinoma 4 months after autologous fat grafting. Plast Reconstr Surg 2013;131:123eY124e 14. Wang G, Ren Y, Cao W, et al. Liposculpture and fat grafting for aesthetic correction of the gluteal concave deformity associated with multiple intragluteal injection of penicillin in childhood. Aesthetic Plast Surg 2013;37:39Y45 15. Ranganathan K, Wong VC, Krebsbach PH, et al. Fat grafting for thermal injury: current state and future directions. J Burn Care Res 2013;34:219Y226 16. Massry GG, Azizzadeh B. Periorbital fat grafting. Facial Plast Surg 2013;29:46Y57 17. Georgiade NG. The surgical correction of temporomandibular joint dysfunction by means of autogenous dermal grafts. Plast Reconstr Surg Transplant Bull 1962;30:68Y73 18. Candirli C, Esen A, Taskesen F, et al. Evaluation of discectomy and dermis-fat grafting on the contralateral side. J Craniofac Surg 2012;23:1654Y1657 19. Meyer RA. The autogenous dermal graft in temporomandibular joint disc surgery. J Oral Maxillofac Surg 1988;46:948Y954 20. Candirli C, Esen A, Taskesen F, et al. Clinicoradiological evaluation of dermis-fat grafts after temporomandibular joint discectomy: a retrospective study. Natl J Maxillofac Surg 2012;3:42Y46 21. Dimitroulis G, Trost N, Morrison W. The radiological fate of dermis-fat grafts in the human temporomandibular joint using magnetic resonance imaging. Int J Oral Maxillofac Surg 2008;37:249Y254 22. Baran CN, Celebioglu S, Sensoz O, et al. The behavior of fat grafts in recipient areas with enhanced vascularity. Plast Reconstr Surg 2002;109:1646Y1651;1652 23. Kononas TC, Bucky LP, Hurley C, et al. The fate of suctioned and surgically removed fat after reimplantation for soft-tissue augmentation: a volumetric and histologic study in the rabbit. Plast Reconstr Surg 1993;91:763Y768 24. Nishimura T, Hashimoto H, Nakanishi I, et al. Microvascular angiogenesis and apoptosis in the survival of free fat grafts. Laryngoscope 2000;110:1333Y1338
* 2014 Mutaz B. Habal, MD
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Experimental Study of Free Fat Grafts in Temporomandibular Joint Disc Anchor Pei Shen, MS, ShanYong Zhang, MD, Chi Yang, MD, and Liang Huo, MS Abstract: This study aims to evaluate the effect of using free fat grafts in preventing adhesion in the temporomandibular joint (TMJ) disc anchor and to observe the outcomes of free fat. Six 3-month-old mini-pigs were included in our study. The left joints were the experimental sides which had undergone releasing the anterior attachments, and free fat from the front of the ear lobe was grafted to the anterior gap. The right joints were the control group, where only the anterior attachments were released. MRIs were carried out and the maximal passive mouth openings were measured before operation, 3 months, and 6 months after operation. The joint tissues and fat specimens were excised after 3 and 6 months. The volume of fat was measured and hematoxylin and eosin (HE) staining was performed. Maximal passive mouth openings were analyzed with SPSS software package by Wilcoxon signed rank test. Maximal passive mouth openings were reduced gradually after 3 and 6 months, accompanied with the deviation of the mandible to the right side. There were significant differences between the 3 groups (P G 0.01). HE staining showed that the surface of the experimental joints was smooth while there was adhesion formation in the control joints. The volume of fat reduced respectively to 67.7% and to 42.6% after 3 and 6 months. HE staining showed new fat lobules were formed after 6 months with obvious fibrosis among the lobules. This study suggested that free fat can survive What Is This Box? A QR Code is a matrix barcode readable by QR scanners, mobile phones with cameras, and smartphones. The QR Code links to the online version of the article.
From the Department of Oral and Maxillofacial Surgery, Ninth People’s Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, People’s Republic of China. Received May 20, 2013. Accepted for publication September 17, 2013. Address correspondence and reprint requests to Dr ShanYong Zhang, Department of Oral and Maxillofacial Surgery, Ninth People’s Hospital, Collage of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai Research Institute of Stomatology, No. 639, Zhi Zao Ju Rd, 200011 Shanghai, People’s Republic of China; E-mail: [email protected] This study was supported by Shanghai Leading Academic Discipline Project (S30206), Natural Science Foundation of Shanghai Municipality (10ZR1418200), and Shanghai Pujiang Talent Plan in 2011, 2013 National Natural Science Foundation of China (81371168), Shanghai Science and Technology Commission (13XD1402300), the Seventh Students’ Innovative Training Project of Shanghai Jiaotong University School of Medicine (2013052). The authors report no conflicts of interest. Copyright * 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000419
The Journal of Craniofacial Surgery
steadily 6 months after operation, with a surviving volume about 42.6% and it can also prevent adhesion formation in the TMJ disc anchor. Key Words: Temporomandibular joint, disc anchor, free fat grafts, adhesion (J Craniofac Surg 2014;25: 253Y257)
T
emporomandibular joint (TMJ) anterior disc displacement without reduction (ADDwoR) is one of the most common TMJ disorders with an incidence of 26%.1 Arthroscopic operation or disc anchors are usually used to treat ADDwoR.2,3 However, in our clinical work, we found that about 3% of patients only treated by disc anchor had a recurrence of anterior disc displacement. For those patients, intra-articular adhesions and scar tissues at the site of the released anterior attachment were found when they underwent a second surgery. In order to reduce recurrence and adhesion, some studies4 reported that the injection of hyaluronic acid into TMJ cavity could reduce fibrous tissue proliferation. However, in the clinical work, because of the existence of gap after releasing the anterior attachments, surgeons usually choose free fat grafts to fill the joint cavity. Although different types of fat grafts have a certain application in TMJ surgery, such as buccal fat pad,5 abdominal dermis fat,6,7 and full-thickness skin subcutaneous fat,8 there have been no clinical and experimental studies to confirm its effect in preventing adhesion and reducing recurrence in TMJ anchor. Besides, the outcomes of free fat in TMJ surgery were not precisely defined. Although Dimitroulis et al9 concluded that non-vascularized fat grafts do not survive transplantation but stimulate neoadipogenesis by animal studies, they used abdominal dermis fat rather than free fat. Whether the outcomes of free fat grafts are the same as dermis fat is not sure. Therefore, we simulated the TMJ disc anchor to evaluate the effect of free fat grafts in preventing adhesion and reducing recurrence and its outcomes.
MATERIALS AND METHODS Experimental Animals and Surgical Technique Six healthy 3-month-old mini-pigs were provided by the Animal Experiment Laboratory of Shanghai Jiao Tong University School of Medicine. The selection standards of animals were as follows: 3 months old, weighing 15 to 17 kg, no teeth missing, good nutrition, and moving freely. The left TMJ was taken as the experimental side, while the right side was taken as the control side. The experimental animals were generally anesthetized using 2.5% amobarbital (1 mL/kg) by intravenous injection after ketamine (2 mL/5 kg) via intramuscular injection. The fur on the preauricular region was shaved and sterilization was performed afterward. Two percent lidocaine (1.5 mL) was injected locally. Preauricular incisions were conducted to expose the TMJ of the mini-pigs. The surface structure, including superficial temporal artery and veins, the parotid gland, and the facial nerve branches in this area, were pulled forward to avoid injury. The anterior attachments on the left joints
& Volume 25, Number 1, January 2014
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
253
The Journal of Craniofacial Surgery
Shen et al
& Volume 25, Number 1, January 2014
FIGURE 1. The implantation process of a free fat to the temporomandibular joint. A, Incision of the surgery. B, Cutting the free subcutaneous fat in front of the ear lobe with the size about 15 mm 5 mm 5 mm. C, Placing the fat flap in the gap. D, Suture in layer.
were released and free fat from the front of ear lobe was grafted in the gap. The size of each fat was 15 mm 5 mm 5 mm. The right joints only had the anterior attachments released, without using free fat grafts. Three hundred twenty thousand units of penicillin was injected intramuscularly 2 times a day for 1 week after operation (Fig. 1).
MRI Examination MRI examination was carried out before, right after, 3 months after, and 6 months after operation. The scanner was a General Electric (Signa; General Electric, Milwaukee, WI) 3.0 T system with the ‘‘Excite’’ platform. Dual phased array dedicated TMJ surface coils were used before and right after operation, while body phased array coils were used after 3 and 6 months because of the growth of the mini-pigs.
Maximal Passive Mouth Opening Measurement The experimental animals were generally anesthetized using ketamine (2 mL/5 kg) via intramuscular injection before, 3 months, and 6 months after operation. A dedicated orthodontic micro-dynamometer was used to measure the distance between the upper and lower incisors as the maximal passive mouth openings. Each parameter was measured 3 times and a deviation of the mandible was observed.
Specimen Preparation and Histological Staining The experimental animals were killed after 3 and 6 months, and the articular cavity was dissected to observe whether there was adhesion formed. Then, the grafted free fat was cut to measure the volume with a 2-mL measuring cylinder. The joint and fat tissues were placed into a 4% formaldehyde solution for fixation. Conventional dehydrated paraffin embedment and serial sections were performed. HE staining was done for light microscope observation.
Statistical Analysis Differences between different times of maximal passive mouth openings were compared with the help of Wilcoxon signed rank test, using the Statistical Package for the Social Sciences (version 16.0; SPSS Inc., Chicago, IL).
RESULTS MRI Observation The radiological presence of grafted tissue was found in all 6 operated joints that were scanned with MRI. Right after the operation, the free fat was mainly of white appearance on the MRI
254
TI-weighted sequences. It gradually changed to off-white and gray after 3 and 6 months, accompanied with a decrease in size of the free fat (Fig. 2).
Maximal Passive Mouth Opening Findings The mandible of all mini-pigs deviated to the right side after 3 and 6 months. The data of maximal passive mouth openings are shown in Table 1. There were significant differences within preoperation, 3 months after, and 6 months postoperation (P G 0.01).
Gross and Histological Observation Gross observation of the specimens: there was obvious synovial hyperemia accompanied by tiny fibrous tissues in the articular cavity after 3 months and visible big cicatricle healing after 6 months on the control joints. Yet the surface of the experimental joints was smooth with no hyperemia or adhesion (Fig. 3). The average volume of the original fat grafts was 0.359 T 0.027 cm3 and it reduced respectively to 0.243 T 0.015 cm3 and 0.153 T 0.021 cm3 after 3 and 6 months, which was 67.7% and 42.6% of the original volume. Hematoxylin-eosin (HE) staining of the joint specimen: the surface of the synovium was neat and smooth in the experimental side. In the control side, there was a large amount of small blood vessel hyperplasia, accompanied with some fibrous tissue after 3 months. After 6 months, a large amount of fibrous tissue was seen in the control side with a few inflammatory cells. However, there was no adhesion formed in the experimental side except for the dilatation of a few vessels (Fig. 4). HE staining of the free fat flap specimen: normal adipose cells are round and slightly flat, arranged in nests or sheets. The nucleus size is consistent and the cell membrane is smooth, and a little of the fiber capsule encircles the fat tissue. However, a large number of plasmocytes and a few of macrophagocytes can be found in the grafts after 3 months. Fibrous septum in the grafts was increased accompanied with some new vessels. After 6 months, the inflammatory cells significantly reduced and some adipose cells clumped into fat lobules, which were close to normal fat tissue. Fat lobule fibrosis was obvious and spread over the grafts (Fig. 5).
DISCUSSION Autologous fat grafts have been used in surgery for over a century.10 Because of their richness, easy material availability, simple operation, and lack of rejection, autologous fat grafts have * 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery
& Volume 25, Number 1, January 2014
Free Fat Grafts in TMJ
FIGURE 2. Images of the free fat on MRI. A, The image of TMJ on the MRI before operation. B, The free fat was observed on the MRI right after operation (red arrow). C, The free fat was observed on the MRI 3 months after operation (red arrow). The signal was decreased and the volume was reduced. D, The free fat was observed on the MRI 6 months after operation (red arrow). The signal was decreased and the volume was reduced further.
drawn much attention from cosmetic and oral and maxillofacial surgeons.11 At present, autologous fat grafts have mainly been used in the following fields12Y16: (1) cosmetic repair, such as breast implants, facial fillers, wrinkle removals, repair of scar concave, as well as youth objectives during the period of aging; and (2) reconstructive repair, including tissue depression after trauma or operation, some congenital malformation and ocular socket plasty, and so on. Autologous fat grafts have achieved positive clinical effects in these fields. In TMJ surgery, dermis-fat grafts were first introduced by Georgiade in 1957 as an interpositional graft in the management of TMJ ankylosis.17 Since then, more and more attention has been paid to the use of fat grafts in this field. Besides TMJ ankylosis, autologous fat grafts were also used for disc repair or as disc replacement material following discectomy.18Y20 Candirli et al18 reported that those who underwent autogenous dermis-fat grafts as disc replacement material following discectomy showed improvement in both mandibular mobility and function 1 year after operation. Dimitroulis et al9,21 confirmed that abdominal dermis-fat grafts could inhibit the growth of new bone and cartilage in both clinical and experimental studies. However, these studies were all about dermis-fat grafts and there is no literature about whether free fat grafts could prevent adhesion and relapse of the disc anchor. In the present study, maximal passive mouth openings were reduced gradually after 3 and 6 months, accompanied by the deviation of the mandible to the right side. This indicated that the function of the right joints was damaged and the joint dysfunction was more serious after 6 months. Gross observation of the control joints showed that
there was obvious synovial hyperemia after 3 months. Accordingly, there was some fibrous tissue in the control joints shown in HE staining. This prompted the conclusion that initial adhesion tissue had formed. Meanwhile, hyperplasia and the dilatation of small blood vessels in the control joints suggested that these blood vessels could continuously provide nutrition for the growth of adhesion tissue. After 6 months, there was a large adhesion under gross observation in the control joints. This was consistent with the results of HE staining that mature fibrosis tissue with fewer blood vessels was observed under the light microscope. Conversely, the joint surface was smooth with
TABLE 1. Maximal Passive Mouth Opening (MPMO) and Deviation of Mandible Before Operation, 3 Months, and 6 Months After Operation (mm) 3 Months After Operation
Before Operation Number 1 2 3 4 5 6
MPMO 65 59 59 62 60 62
T 1.15 T 1.00 T 0.57 T 1.53 T 1.53 T 2.08
Deviation Vertical Vertical Vertical Vertical Vertical Vertical
MPMO* 51 57 51 55 53 52
T T T T T T
2.00 1.53 1.15 1.53 1.00 2.00
6 Months After Operation
Deviation
MPMO**
Deviation
Right Right Right Right Right Right
52 T 1.15 49 T 2.00 47 T 1.53
Right Right Right
*Comparison between preoperation and 3 months after operation, P G 0.001. **Comparison between 3 months and 6 months after operation, P G 0.01.
* 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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& Volume 25, Number 1, January 2014
FIGURE 3. The joint gross specimens after operation. A, The surface of the control side joint was characterized by obvious hyperemia and tiny fibrous tissue (arrow) 3 months after operation. B, The surface of the experimental side joint was smooth, without hyperemia or fibrous tissue (arrow) 3 months after operation. C, Adhesions were formed in the control side joint (arrow) 6 months after operation. D, There was no adhesion in the experimental side joint (arrow) 6 months after operation.
no hyperemia or adhesion occurring after 3 and 6 months. Besides, the grafted free fat was connected to the front of the disc, which increased the length of the disc and prevented the formation of cicatricial healing. These results suggest that free fat can block fibrosis formation and reduce recurrence of disc displacement. Although fat grafts were widely used in surgery, there were different results in the volume change of grafted free, and the loss in volume of grafted fat ranged from 20% to 70% in literature.22,23 In the present study, the volume of grafted fat was reduced respectively to 67.7% and 42.6% after 3 and 6 months. This was in accordance with the results reported by Konanas.23 The reason might be that the form of fat grafts in the 2 studies is the same. Both Konanas
and we used block transplantation, which had the advantages of maintaining normal tissue structure and reducing the destruction of preadipocytes. There are some factors affecting the survival of grafted fat and the most important factors are the form of grafts and the blood supply in the receptor region.22,24 In our study, we used block transplantation which is conducive to establishing blood circulation between the grafts and the receptor region, as well as promoting the maturity of preadipocytes. As a result, block transplantation might be useful for the survival of grafted fat. MRI was also used to evaluate the radiological changes of the free fat in this study. The signal intensity of the grafted fat gradually weakened after operation, which changed from white to off-white
FIGURE 4. Histological observation after joint operation (original magnification 200). A, Hematoxylin and eosin staining of the experimental joint 3 months after operation. The surface of the synovium was smooth. B, Hematoxylin and eosin staining of the control joint 3 months after operation. A large number of small blood vessels were seen in the synovium (arrow) and there was some tiny fibrous tissue above the synovial surface. C, Hematoxylin and eosin staining of the experimental joint 6 months after operation. The surface of the synovium was smooth with a few small vessels. D, Hematoxylin and eosin staining of the control joint 6 months after operation. A large amount of dense fibrous tissue was observed with some inflammatory cells (arrow).
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* 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery
& Volume 25, Number 1, January 2014
Free Fat Grafts in TMJ
FIGURE 5. Histological observation of the free fat (original magnification 100). A, Hematoxylin and eosin staining of a normal subcutaneous fat in the front of the ear lobe. B, Hematoxylin and eosin staining of the free fat 3 months after operation. Small blood vessels were proliferated (red arrow) and macrophagocytes were seen (green arrow). C, Hematoxylin and eosin staining of the free fat 6 months after operation. New fat lobules were formed and interlobular fibrosis was apparent, between which cyst changes were seen.
and gray. This suggested that the components of free fat had been changed and it was confirmed through histological observation. HE staining showed that the grafts were in chronic inflammation as there were a lot of plasmocytes and a few macrophagocytes accompanied by the growth of fibrosis after 3 months. After 6 months, the chronic inflammatory cells significantly reduced and fibrosis was obvious in the fat lobules. Because the signal intensity of fibrosis is lower than fat in MRI, this might result in reduction of signal intensity. Also, some adipose cells clumped into fat lobules, which were close to normal fat tissue. It concluded that the grafted fat survived steadily after 6 months. In a word, we can draw the following conclusions: (1) Free fat can partly survive after 6 months in TMJ disc anchors, with the surviving volume about 42.6%. (2)The use of free fat grafts can also prevent adhesion formation and reduce the recurrence in TMJ disc anchor.
REFERENCES 1. Milano V, Desiate A, Bellino R, et al. Magnetic resonance imaging of temporomandibular disorders: classification, prevalence and interpretation of disc displacement and deformation. Dentomaxillofac Radiol 2000;29:352Y361 2. Zhang S, Liu X, Yang X, et al. Temporomandibular joint disc repositioning using bone anchors: an immediate post surgical evaluation by magnetic resonance imaging. BMC Musculoskelet Disord 2010;11:262 3. Currie R. Arthroscopy for treating temporomandibular joint disorders. Evid Based Dent 2011;12:90Y91 4. El-Hakim IE, Elyamani AO. Preliminary evaluation of histological changes found in a mechanical arthropatic temporomandibular joint (TMJ) exposed to an intra-articular hyaluronic acid (HA) injection, in a rat model. J Craniomaxillofac Surg 2011;39:610Y614 5. Singh V, Dhingra R, Bhagol A. Prospective analysis of temporomandibular joint reconstruction in ankylosis with sternoclavicular graft and buccal fat pad lining. J Oral Maxillofac Surg 2012;70:997Y1006 6. Dimitroulis G. Macroscopic and histologic analysis of abdominal dermis-fat grafts retrieved from human temporomandibular joints. J Oral Maxillofac Surg 2011;69:2329Y2333 7. Dimitroulis G. Condylar morphology after temporomandibular joint discectomy with interpositional abdominal dermis-fat graft. J Oral Maxillofac Surg 2011;69:439Y446 8. Thangavelu A, Santhosh Kumar K, Vaidhyanathan A, et al. Versatility of full thickness skin-subcutaneous fat grafts as interpositional material in the management of temporomandibular joint ankylosis. Int J Oral Maxillofac Surg 2011;40:50Y56
9. Dimitroulis G, Slavin J, Morrison W. Histological fate of abdominal dermis-fat grafts implanted in the temporomandibular joint of the rabbit following condylectomy. Int J Oral Maxillofac Surg 2011;40:177Y183 10. Billings E Jr, May JW Jr. Historical review and present status of free fat graft autotransplantation in plastic and reconstructive surgery. Plast Reconstr Surg 1989;83:368Y381 11. Tucker MR. Dermal graft harvest technique for use in temporomandibular joint disc repair. J Oral Maxillofac Surg 1989;47: 1116Y1118 12. Mori K, Ohta K, Nagano S, et al. [A case of ophthalmic artery obstruction following autologous fat injection in the glabellar area]. Nihon Ganka Gakkai Zasshi 2007;111:22Y25 13. Chaput B, Foucras L, Le Guellec S, et al. Recurrence of an invasive ductal breast carcinoma 4 months after autologous fat grafting. Plast Reconstr Surg 2013;131:123eY124e 14. Wang G, Ren Y, Cao W, et al. Liposculpture and fat grafting for aesthetic correction of the gluteal concave deformity associated with multiple intragluteal injection of penicillin in childhood. Aesthetic Plast Surg 2013;37:39Y45 15. Ranganathan K, Wong VC, Krebsbach PH, et al. Fat grafting for thermal injury: current state and future directions. J Burn Care Res 2013;34:219Y226 16. Massry GG, Azizzadeh B. Periorbital fat grafting. Facial Plast Surg 2013;29:46Y57 17. Georgiade NG. The surgical correction of temporomandibular joint dysfunction by means of autogenous dermal grafts. Plast Reconstr Surg Transplant Bull 1962;30:68Y73 18. Candirli C, Esen A, Taskesen F, et al. Evaluation of discectomy and dermis-fat grafting on the contralateral side. J Craniofac Surg 2012;23:1654Y1657 19. Meyer RA. The autogenous dermal graft in temporomandibular joint disc surgery. J Oral Maxillofac Surg 1988;46:948Y954 20. Candirli C, Esen A, Taskesen F, et al. Clinicoradiological evaluation of dermis-fat grafts after temporomandibular joint discectomy: a retrospective study. Natl J Maxillofac Surg 2012;3:42Y46 21. Dimitroulis G, Trost N, Morrison W. The radiological fate of dermis-fat grafts in the human temporomandibular joint using magnetic resonance imaging. Int J Oral Maxillofac Surg 2008;37:249Y254 22. Baran CN, Celebioglu S, Sensoz O, et al. The behavior of fat grafts in recipient areas with enhanced vascularity. Plast Reconstr Surg 2002;109:1646Y1651;1652 23. Kononas TC, Bucky LP, Hurley C, et al. The fate of suctioned and surgically removed fat after reimplantation for soft-tissue augmentation: a volumetric and histologic study in the rabbit. Plast Reconstr Surg 1993;91:763Y768 24. Nishimura T, Hashimoto H, Nakanishi I, et al. Microvascular angiogenesis and apoptosis in the survival of free fat grafts. Laryngoscope 2000;110:1333Y1338
* 2014 Mutaz B. Habal, MD
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