The document attached has been archived with permission from the Australian Dental Association. An external link to the publisher’s copy is included. Article first published online: 12 MAR 2008The optimum method of temporomandibular joint (TMJ) reconstruction has not been defined despite numerous surgical treatments and several well controlled clinical trials. Animal models offer an experimental method allowing direct comparison of standardized surgical techniques. Advanced osteoarthrosis was induced bilaterally in 12 mature merino sheep. Three months later unilateral surgical reconstruction was performed. Four sheep had discectomy alone, four discectomy with fresh TMJ disc grafts, and four discectomy with fresh auricular grafts. All three surgical methods resulted in some reversal and repair of the osteoarthritic process, with the best result being from the auricular graft, next discectomy alone, next the disc graft, with the untreated osteoarthritic joint showing the most advanced pathosis. This study supports the role of surgical reconstruction in advanced degenerative disease of the temporomandibular joint, in particular, auricular graft reconstruction.Nobumi Ogi, Jun-Ichi Ishimaru, Kenichi Kurita, Yujiro Handa, Robert H.B. Jones, Alastair N. Gos

Goss, A.

Handa, Y.

Ishimaru, J.I.

Jones, R.

Kurita, K.

Ogi, N.

Australian Dental Journal

Adelaide Research &amp; Scholarship

Australian Dental Journal 1997;42:(2):121-4Comparison of different methods oftemporomandibular joint disc reconstruction– An animal modelNobumi Ogi, DDS, PhD*Jun-Ichi Ishimaru, DDS, PhD†Kenichi Kurita, DDS, PhD‡Yujiro Handa, DMD§Robert H. B. Jones, MDS, FRACDS OMS,Alastair N. Goss, DDSc, FRACDS OMS, FICD¶AbstractThe optimum method of temporomandibular joint(TMJ) reconstruction has not been defined despitenumerous surgical treatments and several wellcontrolled clinical trials. Animal models offer anexperimental method allowing direct comparison ofstandardized surgical techniques. Advancedosteoarthrosis was induced bilaterally in 12 maturemerino sheep. Three months later unilateralsurgical reconstruction was performed. Four sheephad discectomy alone, four discectomy with freshTMJ disc grafts, and four discectomy with freshauricular grafts. All three surgical methods resultedin some reversal and repair of the osteoarthriticprocess, with the best result being from theauricular graft, next discectomy alone, next the discgraft, with the untreated osteoarthritic joint showingthe most advanced pathosis. This study supportsthe role of surgical reconstruction in advanceddegenerative disease of the temporomandibularjoint, in particular, auricular graft reconstruction.Key words: Temporomandibular joint, surgery, animalmodels.(Received for publication August 1996. AcceptedSeptember 1996.)IntroductionThe disc is an essential component of thetemporomandibular joint (TMJ). In the normaljoint it has the following function: it spreads thei n t r a - a rticular load, stabilizes the joints duri n gtranslation and decreases the wear of the articularsurface. When the disc is displaced, malformed orworn then this is a key feature of the pathologicprocesses of internal derangement and/or osteo-arthrosis.1,2 In severe cases of intra-articular pathosis,if appropriate non-surgical treatment has been triedand failed then surgical reconstruction isindicated.3,4The ‘best’ method of surgical reconstru c t i o nremains undefined. Some advocate removal of thedisc without replacement,5 others disc removal withreplacement by a range of autogenous grafts such asskin or cart i l a g e ,6 and others discectomy withreplacement with a foreign material such as silicone.7All have received initially good reports although inthe long term joint implants do not do as well asb i o l o gical procedures.8 In recent ye a rs va ri o u sgroups have developed detailed criteria by whichclinical trials should be measured and how theyshould be performed.4,9Common elements in these studies are that foroptimum results clinical trials should be prospective,with strictly standardized operating protocols onage, sex and the clinical stage of the disease beingstandardized. If two techniques are being used thenthere should be randomization of treatment. Largeclinical groups are required with long follow-up.These cri t e ria are easily stated but in clinicalpractice, difficult to apply.Australian Dental Journal 1997;42:2. 121*Oral and Maxillofacial Unit, The University of Adelaide; and Aichi-Gakuin University, Nagoya, Japan.†Oral and Maxillofacial Unit, The University of Adelaide; and GifuUniversity, Gifu, Japan.‡Aichi-Gakuin University, Nagoya, Japan.§Gifu University, Gifu, Japan.,Oral and Maxillofacial Unit, The University of Adelaide.¶Oral and Maxillofacial Unit, The University of Adelaide.Australia Te m p o r o m a n d i bular Joint DisordersResearch Group is an international collaborationbetween Oral and Maxillofacial Surgeons at Aichi-Gakuin Unive rsity in Nagoya, Japan, GifuU n i ve rs i t y, Gifu, Japan, and The Unive rsity ofAdelaide, Adelaide, Australia. This Group hasd e veloped the sheep as a model for temporo-mandibular joint research.10 The results of some 36investigations completed in the last five years haverecently been published as a Monograph.11 The keyfeature of this work is that the animal model is wellc h a r a c t e rized anat o m i c a l l y, phy s i o l o gi c a l l y, bio-mechanically and pat h o l o gi c a l l y. Standardizedmethods of inducing different degrees of internalderangement and osteoarthrosis have been deve l o p e d .Thus the model allows for comparison betweendifferent methods of surgical treatment for disease.This paper presents a comparison of three differentmethods of reconstruction of the disc in precon-ditioned osteoarthrotic joints using the sheep model.122 Australian Dental Journal 1997;42:2.An alternative method is to develop and useanimal models where conditions can be standard-ized. The common laboratory animals (rats andrabbits) have been used, as have primate models. Acommon problem with these studies is that theanimal model has not been fully characterized, andthat the surgical reconstruction is performed onn o rmal and not pat h o l o gic joints. The Ja p a n -Fig. 1. – Right temporomandibular joint – normal. The biconcavedisc is between the temporal and condylar surfaces. The surfaces aresmooth and congruent.Fig. 2. – Right temporomandibular joint – 6 months osteoarthrosis.The disc is central perforated with osteophyte formation peripher-ally and centrally on the condyle. The temporal surface is irregular.TDTDCCFig. 3. – Right temporomandibular joint – 3 months discectomy. Thecondylar surface is flattened and covered by a thickened articularl aye r. The temporal surface is thickened and irregular bu tcongruent with the condyle.Fig. 4. – Right temporomandibular joint – 3 months fresh disc graft.The fresh disc graft is attached posteriorly but not anteriorly. Thereis marked remodelling of the condylar and temporal surfaces withuneven and non-congruent surfaces.Fig. 5. – Right temporomandibular joint – 3 months auricular graft.The auricular graft is in the position of the disc and is attached to theperipheral tissues. The condylar and temporal articular surfacesare thickened but congruent with the disc replacement.CTTGDCTGCT = Temporal boneD = DiscC = CondyleG = GraftMethodTwelve mature merino sheep had bilateral surgicalprocedures to induce osteoarthrosis. The sheep wereanaesthetized with intravenous thiopentothal,i n t u b ated, and the temporomandibular jointsexposed under standardized surgical conditions.Mild damage was caused to the superficial condylarsurface with a scalpel blade and periosteal elevator.The abraded articular surface was irrigated and thewounds repaired in layers. The sheep were returnedto normal field conditions chewing grass within oneweek of the surgical procedure.Three months after the initial surgery, unilateralreconstruction of one joint was performed. Foursheep had discectomy alone, four sheep haddiscectomy followed by replacement with a freshTMJ disc graft, and four sheep had discectomyfollowed by an auricular graft. The contralateraljoint in each animal was left undisturbed.The surgery was performed under similarconditions to that at which the osteoarthrosis wasinduced. Discectomy was performed by removal ofall residual disc tissue. Replacement with fresh TMjoint disc material involved harvesting the disc fromanother animal which was being sacrificed followingo rthopaedic experi m e n t s. The excised disc wa ssutured to the peripheral disc tissue with interruptedresorbable sutures. The period from graft harvest toplacement was less than 30 minutes. The auriculargraft was performed by obtaining a cartilage graftfrom the ipsilateral sheep’s ear. Fo l l ow i n gdiscectomy the auricular graft was sutured in placeusing interrupted resorbable sutures. The donorgraft site was repaired by suturing.At six months following the initial surgery andthree months following the reconstruction, thesheep were sacrificed by a lethal overdose ofbarbiturates. The TMJ was removed en bloc with aband saw and fixed in formalin. The TMJ was radio-graphed from the lateral and anteri o r - p o s t e ri o ra s p e c t s. The blocks were then decalcified andvertically sectioned into anterior, lateral, and medials p e c i m e n s. These were photographed prior tohistologic processing.Four TMJs from two unoperated sheep weresimilarly processed as controls. The experiment wasperformed in accordance with the ethical guidelinesof The University of Adelaide, and the care of theanimals was directed by a veterinary surgeon.ResultsThe normal macroscopic appearance of the sheeptemporomandibular joint is shown in Fig. 1.The six month osteoarthrotic joints showing thetypical features of advanced osteoarthrosis is shownin Fig. 2.The discectomy alone joints are shown in Fig. 3.The discectomy with fresh temporomandibularjoint disc graft is shown in Fig. 4.The auricular graft replacement is shown in Fig. 5.Generally there was a similar appearance in allspecimens within each group.DiscussionThis study shows that all three surgical inter-ventions resulted in some reve rsal and repair of theo s t e o a rthrotic process of the sheep temporo-m a n d i bular joint. Generally the auricular gr a f tresulted in the gr e atest degree of improve m e n t ,d i s c e c t o my alone next, the fresh disc graft the least;but all showed gr e ater evidence of repair than theu n t r e ated osteoarthrotic control. The advantage ofanimal models are that they allow comparison ofstandardized pathosis treated with standardizedsurgical techniques. This allows for accurate andreproducible demonstration of the biologic responseto treatment.A number of different species of animals havebeen tested for temporomandibular joint studies.Rats and rabbits are commonly used but there aremarked dissimilarities in size, anatomy and functionof the TMJ from humans. There is greater similaritywith the TMJ of primates, but there are seriousissues concerning the cost and ethics of primateexperimentation.The sheep has the advantages of having a TMJwhich is similar in size, thus allowing similar surgicaltechniques; it is a robust animal and it has highethical acceptability.1 0 There are differences inmasticatory physiology but these have been wellcharacterized. Sheep spend a considerable part oftheir life cropping grass and then subsequentlyruminating. Thus there is considerable masticatoryactivity which allows for condensation of the lengthof experiments.11The current experiment could be criticized on thegrounds of small sample size, unilateral surgicalprocedures and ethics. The small size is in partdictated by cost, but as homogeneous results wereachieved in the groups, the use of four joints isappropriate. Current studies by the Japan-AustraliaResearch Group on unilateral condylectomy showthat there is an alteration in biomechanics of the jaw.This is confirmed by preliminary intra-articularpressure experi m e n t s. Howe ver performing uni-l ateral reconstruction on diseased joints allow scomparison between experimental and control inthe same animal. Ethically there is wide acceptanceof the sheep as an acceptable animal model. It isnoted that the degenerative process is not inflamedand thus not osteoarthritic, hence the use of theterm osteoarthrosis. The involved animals returnrapidly to normal masticatory function.Good clinical results have been presented over along term with discectomy alone.5 PhilosophicallyAustralian Dental Journal 1997;42:2. 123however it is a mutilative procedure and thus there isa tendency for surgeons to prefer some type of discreconstruction. Good results have been presentedfor discectomy with auricular grafts replacement.6,12The use of fresh disc grafts has not been reported inclinical trials. Similar types of graft transfer havehowever been reported for the knee. Given that theuse of TMJ disc grafts replaces diseased tissue withnormal tissues of the same type and function, thenthis concept needs to be further pursued. Clinicallythe use of alloplastic materials has resulted in failurein the medium to long term.8,13,14 Similar results havebeen demonstrated in the sheep using silicone,15 andguided tissue regeneration membranes. The alloplasticm at e rials migr ate and fragment inducing a destru c t i veforeign body reaction.It would be overly simplistic to directly extrapolatethese research findings to the clinical situation. Itdoes however provide insight into the biologicalprocesses which occur with these grafts. It alsoconfirms the surgical clinical view that surgicalreconstruction of joints does have a place in themanagement of advanced disease.AcknowledgementThe authors wish to gratefully acknowledge thesupport of The Australian Dental Research FundInc. for this experiment and others in the sheepmodel series.References01. D o lwick FM. Intraarticular disc displacement. Pa rt I. Itsquestionable role in temporomandibular joint pathology. J OralMaxillofac Surg 1995;53:1069.02. Stegenga B, De Bont LGM, Boering G. Osteoarthosis as a causeof craniomandibular pain and dysfunction. J Oral MaxillofacSurg 1989;47:249-56.03. Israel HA. Current concepts in the surgical management oftemporomandibular joint disorders. J Oral Maxillofac Surg1994;52:289-94.04. Goss AN. Towards an international consensus on temporo-mandibular joint surgery. Report on the Second InternationalConsensus Meeting, Buenos Aires, Argentina. Int J OralMaxillofac Surg 1993;22:78-81.05. Eriksson L, Westesson PL. Long term evaluation of meni-sectomy of the temporomandibular joint. J Oral Maxillofac Surg1985;43:263-9.06. Martukas VJ, Lachner J. The use of autogenous auricularc a rtilage for temporomandibular joint disc surgery. J OralMaxillofac Surg 1990;48:438.07. Hansen WC, Deshazo BW. Silastic reconstruction of thet e m p o r o m a n d i bular joint meniscus. Plast Reconstruct Surg1969;43:388-91.08. Ericksson L, Westesson P-L. Deterioration of temporary siliconeimplants in the TMJ. A clinical and arthroscopic follow up study.Oral Surg 1986;62:2-6.09. Holmlund A. Aspects of evaluation and treatment outcome andcriteria for success. Int J Oral Maxillofac Surg 1993;22:91.10. Bosanquet AG, Goss AN. The sheep as a model for temporo-mandibular joint surgery. J Oral Maxillofac Surg 1987;16:600-3.11. Goss AN, Kurita K, McMahon L., eds. The sheep as a model fortemporomandibular joint disorders. Adelaide: The University ofAdelaide, 1995. Monograph.12. Hall HD, Link JJ. Diskectomy alone and ear cartilage inter-position graft in joint reconstruction. Oral Maxillofac SurgClinics Nth Am 1985;1:329.13. Ryan DE. The Proplast-Teflon dilemma. J Oral Maxillofac Surg1989;47:222.14. Spagnoli D, Kent JN. Multicentre eva l u ation of temporo-m a n d i bular joint Proplast Teflon disk implant. Oral Surg1992;74:411-21.15. Bosanquet AG, Ishimaru J, Goss AN. The effect of silasticreplacement following discectomy in sheep temporomandibularjoints. J Oral Maxillofac Surg 1991;49:1204-9.Address for correspondence/reprints:Professor Alastair N. Goss,Oral and Maxillofacial Surgery Unit,The University of Adelaide,Adelaide, South Australia 5005,Australia.124 Australian Dental Journal 1997;42:2.

Comparison of different methods of temporomandibular joint disc reconstruction - An animal model

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Comparison of different methods of temporomandibular joint disc reconstruction - An animal model

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Comparison of different methods of temporomandibular joint disc reconstruction - An animal model

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Adelaide Research & Scholarship