Research Paper

TMJ Disorders

Int. J. Oral Maxillofac. Surg. 2013; 42: 218–222http://dx.doi.org/10.1016/j.ijom.2012.11.004, available online at http://www.sciencedirect.com

A new surgical classification fortemporomandibular jointdisordersG. Dimitroulis: A new surgical classification for temporomandibular joint disorders.Int. J. Oral Maxillofac. Surg. 2013; 42: 218–222. # 2012 International Association ofOral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Abstract. The role of temporomandibular joint (TMJ) surgery is ill-defined, so auniversal classification is needed to collate the evidence required to justify thesurgical interventions undertaken to treat TMJ disorders. The aim of this article is tointroduce a new classification that divides TMJ disorders into 5 categories ofescalating degrees of joint disease that can be applied to TMJ surgery. Using acategory scale from 1 to 5, with category 1 being normal, and category 5 referring tocatastrophic changes to the joint, the new classification will provide the basis forenhanced quantitative and descriptive data collection that can be used in the field ofTMJ surgery research and clinical practice. It is hoped that this new classificationwill form the basis of what will eventually become the universal standard surgicalclassification of TMJ disorders that will be adopted by both researchers andclinicians so that ultimately, the role of TMJ surgery will be based on evidencerather than conjecture.

0901-5027/020218 + 05 $36.00/0 # 2012 International Association of Oral and Maxillofacial Surge

G. DimitroulisMaxillofacial Surgery Unit, Department ofSurgery, St. Vincent’s Hospital Melbourne,The University of Melbourne, Australia

Keywords: temporomandibular joint; surgery;classification; disorders.

Accepted for publication 8 November 2012Available online 31 December 2012

The role of temporomandibular joint(TMJ) surgery is not well defined.1 Partof the reason is that hard evidence islacking since, unlike orthopaedic surgery,there is no universal classification thatallows the collection of standard data thatcan be used to compare the various tech-niques published in the literature. Tempor-omandibular disorder (TMD) specialistshave been proactive in establishing theResearch Diagnostic Criteria (RDC) forTMD and have used this as the basis forassessing various non-surgical strategies.2

The field of TMJ surgery has only man-aged to come up with what constitutessuccessful TMJ surgery outcomes.3

Evidence is needed to define the role ofTMJ surgery, and evidence needs data

which can only be derived from universalmedical codes. Universal medical codesare collected from classifications and whatthe field of TMJ surgery needs is a uni-versal classification in order to collate theevidence required to justify the surgicalinterventions undertaken to treat TMJ dis-orders. The aim of this article is to intro-duce a new surgical classification thatincludes all TMJ specific disorders thatcan be applied to future studies related toTMJ surgery.

Reasons for classification

Medical classification is the process oftransforming descriptions of diagnosesand procedures into universal medical

code. It is from these codes that datacan be collected and analysed for thepurpose of providing the hard evidenceneeded to determine whether TMJ surgeryis effective in providing material benefit topatients.1 In other words, the hard evi-dence for TMJ surgery can only be securedwith a universally recognized surgicalclassification of TMJ disorders.

Presently, there are 3 main classifica-tions related to TMD; the Research Diag-nostic Criteria (RDC) for TMD,2 theWilkes Classification4 for TMJ internalderangement, and the most recent Amer-ican Academy of Orofacial Pain (AAOFP)Classification of TMD.5 The RDC-TMDclassification2 is the most widely usedby TMD researchers who stress the

ons. Published by Elsevier Ltd. All rights reserved.

Surgical classification for TMJ disorders 219

Table 1. Criteria for new TMJ surgical clas-sification.

Simple – easy to understand and rememberClear – unambiguous description of eachcategoryFocused – on the TMJInclusive – of all TMJ disorders and diseasesSpecific – so that patient populations can beeasily defined and comparedUniversal – adopted by all TMD cliniciansand researchers

Table 2. Surgical classification of TMJdisorders.

Category 1TMJ normalNo surgery required or indicated

Category 2TMJ minor changes (all joint components

are salvageable)TMJ arthrocentesis/arthroscopic lavage

Category 3TMJ moderate changes (most joint

components are salvageable)TMJ operative arthroscopy/TMJ

arthroplastyCategory 4

TMJ severe changes (few jointcomponents are salvageable)

TMJ discectomy � condylar surgeryCategory 5

TMJ catastrophic changes (nothing in thejoint is salvageable)

TMJ resection � total joint replacement

Table 3. Category 1: Normal TMJ.

Clinical presentationTMJ painNo joint noisesNo history of locking or dislocationFull range of jaw movementNormal chewing

Radiological featuresOPG – normal condylesMRI – normal TMJ

DiagnosisJoint contusion – acute traumaMyofascial painEar pathology – otalgiaNeuropathicPsychogenic

TreatmentMedication � splintSurgery has no role

importance of psychosocial dysfunction(Axis II) as opposed to physical disorders(Axis I) and come up with a wide varietyof complex calculations that often havelittle bearing on clinical practice. TheRDC-TMD has remained firmlyembedded in the research world with littleuse in clinical practice.

The Wilkes classification4 is the mostwidely used classification that has beenadopted by surgeons who treat TMJ dis-orders. Its widespread adoption is linkedto its simplicity in describing escalatingjoint pathology in 5 stages, but it concen-trates on only 2 disorders (internalderangement and osteoarthritis) and failsto include other TMJ disorders such asankylosis and tumours which are coveredby a host of other sub-classifications6,7

that will not be elaborated here.The AAOFP classification of TMD5 has

refocused its attention on articular disor-ders with a more widespread appreciationof joint disease, not confined to internalderangement, but also ankylosis, traumaand even developmental conditions of theTMJ are listed. The masticatory muscledisorders are listed simply as local, gen-eral and centrally mediated which reflectsthe poor understanding of extra-articulardisorders related to TMD. While theAAOFP classification5 of TMD is a vastimprovement on the cumbersome RDC-TMD,2 there is still a problem when itcomes to data collection as the AAOFPclassification does not allow for degree ofdisability which is quantifiable like theWilkes Classification.4

In 1994, Dolwick and Dimitroulis8 pub-lished a table which divided indicationsfor TMJ surgery into relative and absolute.Relative indications were stipulated forcommon TMJ disorders such as internalderangement and osteoarthrosis, whileabsolute indications were reserved for lesscommon TMJ disorders such as ankylosisand neoplasia of the TMJ. Surgical indica-tions such as this only indicate when TMJsurgery should be considered, but does notstipulate what kind of surgery is requiredand for which disease.

New classification

In the development of a new classification,it is essential to purge the weaknesses andbuild on the strengths of previous classi-fications. Dozens of new medical classifi-cations are introduced to the literatureevery year, but history has shown thatonly the simplest, such as the classic LeFort classification for midface injuries,9

that are easy to remember and simple tounderstand are universally adopted. The

criteria for the new classification are givenin Table 1. The purpose of this new clas-sification (Table 2) is to specify the role ofTMJ surgery in all TMJ disorders in agraded fashion across a spectrum of 5categories of escalating degrees of jointdisease.

Category 1: TMJ normal joint

No surgery is required. In this category(Table 3), a patient may present with painspecifically centred around the TMJ butreport no history of locking, dislocation ordifficulty chewing. There are no audible orpalpable joint noises and the patient exhi-bits a full range of jaw movement withsymmetrical opening. Plain films, mag-netic resonance imaging (MRI) and com-puted tomography (CT) scans shownormal joint with no radiological abnorm-alities (Fig. 1). The patient may havesustained recent acute trauma followingwhiplash, fall or assault or experienced anear infection. In long standing cases theTMJ arthralgia may be secondary to myo-fascial pain, fibromyalgia or part of aneuralgia or psychosomatic disorder.TMJ surgery has no role in these situationsand patients must be carefully assessed for

other ailments that may be contributing toor exacerbating the TMJ arthralgia.

Category 2: TMJ minor changes

All joint components are salvageable. Inthis category (Table 4) a patient maypresent with intermittent TMJ pain, jointclicking and occasional locking. Plainfilms demonstrate normal condyles butMRI may show mild disc displacementwith reduction or excess fluid in the jointindicative of inflammation (Fig. 2). TMJarthrocentesis may be appropriate forcases of acute onset closed lock andTMJ arthroscopy may demonstrate mildinflammation with occasional adhesions.Both procedures may help unlock a stuckjoint, but the primary treatment modalityremains conservative (i.e. anti-inflamma-tory medication, jaw rest, soft diet).

Category 3: TMJ moderate changes

Most joint components are salvageable. Inthis category (Table 5), patients reportpainful long-standing closed lock (>2months), joint swelling or painful recur-rent dislocation of the TMJ. The patientmay report difficulty chewing with mod-erate to severe pain levels exacerbated byjaw function. Mandibular opening isrestricted either because of fear of dislo-cation or actual joint pain which oftenresults in deviation of the mandible tothe affected side. Because of the restrictedmouth opening joint noises are oftenabsent. While plain films may show nor-mal condylar morphology, MRI showsnon-reducing disc displacement. The discmay exhibit mild contour deformity andthere may be a prominent articulareminence that obstructs the backward pathof the translated condyle (Fig. 3). Diag-nostically, the patient may have suffered

220 Dimitroulis

Fig. 1. Normal TMJ. Category 1 joint which demonstrates a normal TMJ on MRI. The mainpresentation is TMJ arthralgia but TMJ surgery is not indicated if there are no functionaldisturbances. Category 1 patients offer researchers the ideal control group with which tocompare surgical outcomes in other categories.

Table 5. Category 3: Moderate TMJ changes.

Clinical presentationPainful chronic closed lockRecurrent joint swellingPainful recurrent dislocation

Radiological featuresOPG – normal condylesMRI – disc displacement without reduction

Disc normal or mildly deformed contourProminent eminence

DiagnosisModerate TMJ internal derangementRecurrent TMJ dislocationTMJ synovial chondromatosisDislocated condylar fracture

TreatmentTMJ arthroscopy (operative)TMJ arthroplasty – disc plication/

repositioning � eminectomyModified condylotomyORIF fractured condyle

an acute event such as a fracture disloca-tion of the condylar head or simply dis-location of the condyle. In long standingcases, the patient may be suffering frommoderate TMJ internal derangement orsynovial chondromatosis. In category 3cases, the patient would benefit fromoperative TMJ arthroscopy, modified con-dylotomy, TMJ arthroplasty consisting ofdisc repositioning with or without emi-nectomy, or open reduction and internalfixation of displaced condylar fractures.

Category 4: TMJ severe changes

Few joint components are salvageable. Inthis category (Table 6), patients reportconstant joint pain with painful crepitusand mildly limited mouth opening. Chew-ing is very painful and yawning is almostimpossible without provoking severe pain.Plain films show radiological signs ofearly changes in condylar morphologysuch as flattening and beak type deformi-

Table 4. Category 2: Minor TMJ changes.

Clinical presentationIntermittent joint painJoint clickingOccasional locking

Radiological featuresOPG – normal condylesMRI – disc displacement with reduction

Disc and condyle normal contourDiagnosis

Early TMJ internal derangementJoint inflammation/adhesions

TreatmentTMJ arthrocentesisTMJ arthroscopic lavage

ties of the condylar head which are betterseen on cone-beam CT scans. MRIsdemonstrate severely degenerate, dis-placed and deformed articular discs(Fig. 4) which may sometimes demon-strate perforations. Early condylarchanges such as osteophytes and smallsubcondral cysts with loss or thinning ofcartilage layer may be seen on cone-beamCT scans. The clinical picture is that ofsevere TMJ internal derangement withearly osteoarthritis. This category mayalso include rare metabolic, inflammatoryor developmental disorders of the TMJ.TMJ discectomy with or without debride-ment, shaving or surgical reduction of thecondylar head, articular eminence andglenoid fossa is the mainstay of treatment.

Fig. 2. Minor TMJ changes. Category 2 joint

resulted in locking and pain on function. TMJ arthuseful in these cases, although non-surgical measuat whether TMJ arthrocentesis/arthroscopy signipared to conservative measures alone in categor

Category 5: TMJ catastrophic changes

No joint components are salvageable.Patients in this category (Table 7) reportintolerable low grade joint pain and jointcrepitus with constant locking and inabil-ity to chew anything solid. Plain filmsshow obvious degenerative changes tothe condyle which is better depicted oncone-beam CT scans which show irregulararticular surface and large subchondralcysts. MRI shows severely degenerateddisc which is often difficult to visualizewith low signal from the condyle thatappears irregular and deformed. Diagnos-tically, these patients suffer from TMJosteoarthritis or degenerative joint diseasethat may be the result of multiple previousoperations. Where the joint pain is absentor tolerable, the patient may have TMJosteoarthrosis or in rare cases, TMJ anky-

showing disc displacement on MRI that hasrocentesis or TMJ arthroscopic lavage may beres are still important. Future studies may lookficantly reduce the treatment time span com-y 2 patients.

Surgical classification for TMJ disorders 221

Fig. 3. Moderate TMJ changes. Category 3 joint showing dislocation of TMJ with condyle stuckbeyond the articular eminence. In cases of recurrent TMJ dislocation, operative TMJ arthro-scopy, modified condylotomy or TMJ eminectomy with disc plication may be appropriate.Whichever technique is the most effective can only be determined by randomized clinicalstudies involving category 3 patients.

Table 6. Category 4: Severe TMJ changes.

Clinical presentationConstant joint painPainful crepitusMildly limited mouth openingPainful chewing

Radiological featuresOPG – early condylar changesCT scans – mild to moderate condylardegenerationMRI – severely degenerated, displacedand deformed disc

Early condylar changes – osteophytes,flatteningDiagnosis

Advanced TMJ internal derangementRare TMJ disorder – metabolic,

inflammatory or developmental joint diseaseTreatment

TMJ discectomy � condyloplasty/shaveDebridement of glenoid fossaReduction of eminence

losis (Fig. 5), condylysis or tumour.Patients in this category would benefitfrom condylectomy, discectomy and totaljoint replacement where feasible.

Discussion

For many years, the Wilkes classification4

has served as the unofficial standardclassification for TMJ surgeons worldwide.The simplicity of the stages described andescalating disease level with each stagemade it universally applicable to the most

Fig. 4. Severe TMJ changes. Category 4 joindegenerate disc on MRI with degenerate bony chaso TMJ discectomy is most appropriate with perhlook at whether disc repair is possible in catego

common TMJ disorders treated by oral andmaxillofacial surgeons (internal derange-ment and osteoarthrosis). The new classi-fication embodies the simplicity of theWilkes classification4 by keeping the 5stages of disease but broadening the defini-tion of each category to include other lesscommon TMJ disorders such as disloca-tions and tumours as well as ankylosis.

In the development of a new surgicalclassification for TMJ disorders it wasnecessary to include all disorders thatare amenable to surgical intervention.

t showing severely displace, deformed andnges in the condyle. The disc is unsalvageableaps a high condylar shave. Future studies mayry 4 patients.

The classification not only describes theclinical and radiological features of eachcategory, but also suggests the degree ofsurgical intervention. Thus when a studypresents results on the treatment outcomesof category 3 patients, for example, read-ers will immediately understand the cri-teria for category 3 patients that wereinvolved in the study and future meta-analyses of treatment options for category3 patients will be easier to assess andanalyse because of the standardized clas-sification.

The major theme behind each categoryis whether any of the joint components aresalvageable by surgery, regardless of thediagnosis. A scale of 1–5 with progressiveincreased severity of joint disease allowsnumerical quantification to aid data col-lection, with category 1 being normal andcategory 5 referring to catastrophic

Table 7. Category 5: Catastrophic TMJchanges.

Clinical presentationIntolerable low grade painConstant crepitusLockingMalocclusionUnable to chew anything solid

Radiological featuresOPG – obvious degenerative changes to

condyleMRI – disc destroyed/difficult to seeCT scan – condyle severely degenerate

DiagnosisTMJ osteoarthritisTMJ condylysisTMJ ankylosisTMJ tumour

TreatmentTMJ resectionTMJ total joint replacement

222 Dimitroulis

Fig. 5. Catastrophic TMJ changes. Category 5 joint on coronal CT scan showing catastrophicchanges to the TMJ resulting in extensive bony ankylosis. TMJ surgical resection with total jointreplacement is normally indicated although some may argue the medially displaced condylemay be salvageable in some cases.

changes to the joint. The role of the newclassification should not only be confinedto research data collection but also allowclear communication between clinicians.So if a clinician refers a patient with acategory 1 TMJ, the recipient clinicianwill immediately understand that whilethe TMJ is painful, there are no clinicalor radiological signs of joint disease thatwould require surgical intervention.Whereas, if the TMJ is described ascategory 5, the recipient clinician willimmediately appreciate that there are cat-astrophic changes in the joint so that noneof the joint components are salvageable.This classification not only helps codifythe diagnosis but also underscores thesalvageable potential of various joint com-ponents that may aid surgical treatmentplanning. The lack of a definitive methodof collecting data to prove the efficacy ofthe numerous TMJ surgical proceduresdescribed in the literature is glaringlyobvious.1 With the help of this classifica-tion, the TMJ patient populations will bebetter defined and easily compared, parti-cularly when it comes to multicentre clin-ical trials.1

Having presented this new classificationas a means of research data collection andcommunication between clinicians, itmust be emphasized that this is only apreliminary attempt at trying to standar-dize understanding of TMJ disorders. As itis a new classification, there will be plenty

of discussion and debate about the essen-tial requirements for clear and unambig-uous interpretations of each category. Aconsensus conference may help to resolvemany of the issues raised by this newclassification, including the need for sucha classification. Independent research isessential to validate the reliability andapplicability of this classification toTMJ disorders that surgeons would finduseful and practical in their everyday clin-ical practice.

Progress in TMJ surgery can only beachieved on the back of a simple andstraightforward classification that is uni-versally accepted and adopted by bothresearchers and clinicians. It is hopedthat this new surgical classification willform the basis of what will eventuallybecome the universal standard surgicalclassification of TMJ disorders that willbe adopted by all oral and maxillofacialsurgeons.

Funding

None.

Competing interests

None declared.

Ethical approval

Not required.

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