Temporomandibular joint ankylosis: An Indian experience U. C. Sarma, MS, and P. K. Dave, MS, New Delhi, India DEPARTMENT
OF ORTHOPAEDICS,
ALL-INDIA
INSTITUTE
OF MEDICAL
SCIENCES
Seventy-five condylectomy and coronoidectomy specimens of temporomandibular joint ankylosis in 61 patients were studied. Fourteen patients had bilateral ankylosis, six of whom had fibrous ankylosis on one side. There were two types of ankyloses: intra-articular and juxta-articular. Intra-articular ankylosis was seen only in reankylosis or in postinfective cases. Sixty-six cases were posttraumatic juxta-articular ankylosis. A rudimentary temporomandibular joint with an atrophic condylar articular surface was found in all juxta-articular ankyloses. The size of new bone in the specimens varied from 0.5 to 3 cm. Fusion of the extra-articular bone mass with tympanic plate was also observed. Contracture of temporalis muscle was noted in all the cases, which made excision of the coronoid processes mandatory in all the arthroplasties. Arthroplasty early in childhood did not hamper growth; instead, facial remodeling was enhanced. (ORAL SURG ORAL MED ORAL PATHOL 1991;72:660-4)
T
emporomandibular joint (TMJ) ankylosis is not uncommon in India. These patients, usually of lower socioeconomicstatus, are seenat varied intervals after the onset of the disease,which is usually early in childhood. Eating is difficult, and patients rely mostly on having the food pushedthrough the vestibule of the mouth and then behind the last molar teeth. Oral hygiene is poor. The treatment of this condition is surgical. The pathologic changes encountered in this ankylosis dependson the cause of the diseaseand in most casesa distinct correlation is possible.A knowledge of the pathologic anatomy of this crippling diseaseis essential to explain the strategy of the treatment and to avoid complication in this relatively difficult but rewarding surgery. The purpose of this article is to highlight the pathologic anatomy of this condition and to correlate it with the etiologic conditions. MATERIAL
AND METHODS
Since the mid- 1960sthe orthopedic surgeonsof the All-India Institute of Medical Sciences have been performing condylectomy and coronoidectomy for TMJ ankylosis with excellent results. The method of treatment and the results of surgery have been published by Chandra and Dave.’The entire bone mass, 7/12/29899
660
Fig. 1. Specimens excisedfrom bilateral TMJ ankyloses. Left, Specimens from patient with bilateral bony ankylos-
es. Right, Fibrous ankylosis in one side (inner specimen).
consisting of the condyle, the coronoid process,and the new bone, was removed in one block subperiosteally and preservedfor postoperative studies. Of 206 cases surgically treated, 75 specimensfrom 61 patients were available for study. This included three casesof interposition arthroplasty that had reankylosed. The gross pathologic findings were noted, the amount of extra bone measuredand the status of the joint surfaces noted. The size and shape of the coro-
Volume 72
Number6
Fig. 2. Computerizedaxial tomographof patient with bilateralTMJ ankylosis.Note sizeof juxta-articularbone. Atrophiccondyle(arrow) is seenseparatefrom newbone. Juxta-articularbonemassshowsevidenceof pseudoarthrosis (broken arrow). However,at surgerywe nevernoticed pseudoarthrosis.
noid processwas examined and observedfor any evidence of new bone formation. These were supplementedwith operativeand clinical observationswherever necessary. OBSERVATION
The ankylosis was bilateral in 14 patients, and the remaining 47 had unilateral ankylosis: 22 on the left side and 25 on the right. There was a total of 69 bony ankylosesand six fibrous ankyloses(Fig. 1). Fibrous ankylosis was found on only one side of some of the bilateral ankylosis patients; that is, 8 of the 14 bilateral ankyloses involved bony ankylosis in both the joints and the other six involved bony ankylosisin one joint whereas the other joint had fibrous ankylosis. Primary fibrous ankylosis was not seenin any of the specimensexamined. The bony ankyloseswere of two types: intra-articular and juxta-articular. In the intra-articular type the bone extendedfrom one articular surface to the other, replacing both of them entirely; in the juxtaarticular type a variable massof bone extendedfrom the ramus of the mandible to the zygomatic arch, pushing the condylar articular surface medially. On computedtomographicscans,the TMJ demonstrated as a low-density line, giving an appearanceof pseudoarthrosis (Fig. 2). Intra-articular ankylosis was seen only in those caseswhich had reankylosed after some attempt at arthroplasty and in postinfectiveankylosis;nine specimens showed intra-articular ankyloses, of which
Fig. 3. Specimensfrom casesof reankylosisafter attemptedarthroplastywith siliconeelastomerballs(lefj and
silicone elastomer pulley (right). Note that one of balls (arrow) is completely incorporated in new bone mass.Silicone elastomer pulley also had same fate.
three followed attempted interposition arthroplasty (i.e., siliconeelastomerpulley, silver foil) (Fig. 3); five showedreankylosis after attempted excision arthroplasty by excisingthe condyleonly; one specimenwas probably causedby ear infection. The remaining 60 specimenswere of the juxtaarticular type. The agedistribution of this variety was uniform. The chin scar in most casesservedas a definite clue suggestingthe etiologic factor to be traumatic in these ankyloses.It is pertinent to mention here that 190 of the 206 surgically treated caseswere posttraumaticjuxta-articular ankylosis.The bridging massof bone betweenthe ramus of the mandible and the zygomatic arch had its maximum thicknessin the region of the condyleand then sharply narroweddown to merge imperceptibly with the ramus of the mandible about 2 cm below the zygomatic arch. The thicknessof this new bone was variable, 0.5 to 3 cm at the site of maximum diameter. The size of the bone mass dependedon the age and size of the mandible. It extended medially under the temporal fossatoward the lateral pterygoid plate but was never fused to the lateral pterygoid plate becauseof the attachmentsof the pterygoid muscles. Anteriorly the bone mass sometimes extendedpast the mandibular notch to the medial side of the coronoid process. Posteriorly, it extendsup to the tympanic plate; the fusion of bone mass with the latter was observedin 12 specimens (Fig. 4). In the juxta-articular types the condyle was atrophic and was pushed medially, anteromedially, or posteromedially.It retained its attachment to lateral pterygoid muscle despite the altered locations. In at
662
Sarma and Dave
ORAL SURG ORAL M E D ORAL PATHOL
December I99 I
Fig. 4. Massive juxta-articular bone that had fused with tympanic plate.
Fig. 5. Specimenswith varying degreesofjuxta-articular bone. Upper pair shows condyle (arrow) and bone mass separate from each other. Middle pair displays condylar articular surface in the samemassof bone but at lower level. Lowerpair showscompletefusion of condyle with new bone, the former being demarcated by remnants of articular cartilage only.
least 50% of the cases, usually in children, an attenuated disk was present, signifying the intact joint and the juxta-articular ankylosis. The condylar articular surface was always covered by a thin layer of articular cartilage. Its size was variable and seen in an oval, semilunar, or crescent shape. The capsule on the lateral aspect of the affected joint could not be identified even at operation, although a rudimentary synovial joint persisted between the altered condylar articular surface and condylar fossa. In sharp contrast to the findings in the juxta-articular types, in the intra-articular types of ankyloses, the condyle disappeared completely as a result of surgery or disease, no articular surface was identifiable, and the bone mass was often smaller, In fibrous anky-
Fig. 6. Specimen from intra-articular ankylosis, where bone mass is smaller and remnant of condyle is not seen.
loses the condyles remained intact, although they were atrophic and the articular cartilage, as in other joints with fibrous ankylosis, was degenerated and was replaced by fibrous tissue. The coronoid process, although of variable size, was well preserved. This remained separated from the juxta-articular mass of bone. The outer surface of the coronoid process was fused with inner surface of zygomatic arch in two specimens. Although not included in this group of specimens, rarely have we seen bone as a single mass extending from the tympanic plate to the anterior border of the coronoid process, thus converting the tympanic plate, zygomatic arch, condyle, and coronoid process into a single mass of bone. The temporalis muscle, although maintaining its normal attachments both above and below and retaining its normal contractile muscular element, was secondarily contracted as a result of prolonged duration of the ankyloses. The masseter muscle was contracted in an identical way. Overall, the mandibles were smaller and at times grossly retracted. In the unilateral cases the chin was deviated to the affected side. The increased depth of the pregonial notch in the affected side was a diagnostic, radiographic and clinical finding. Dental malocclusion and poor alignment of teeth were invariably found in all cases of TMJ ankylosis. All these changes were secondary and were evidences of the presence of the ankylosis during the period of growth. DISCUSSION
Ankylosis of the TMJ has extensive secondary effects. These secondary changes are cosmetically important, of course, but the overriding surgical significance is the problem of postoperative reankylosis and the preservation of an adequate range of motion in the
Volume 72 Number 6
affected joint. The most important of the secondary effects are the contractures of the temporalis and massetermuscles.Unless these contractures are relieved, arthroplasty will be unsuccessful.The other secondary change of surgical significance is the fibrous ankylosis of the oppositeTMJ. The deviation of the chin, the regressionof the mandible, the facial asymmetry and the dental malocclussiontend to revert to normal as the postoperativenormal excursions of the mandible are reestablished.Hence the earlier the operation, the better the prognosis. It is evident from the pathologic anatomy of the ankylosedjoint that three factors prevent mobility in the joint: the bridging bonemassbetweenthe condyle and condylar fossa, the contracted muscles,and the occasionalfusion of the coronoid processwith zygomatic arch. It is imperative that all three be corrected concurrent with an arthroplasty of the joint. Failure to do so results in reankylosisor in lim ited successof the procedure.The removal of the coronoidprocessin addition to the condylar massof bone servestwo purposes:effectively lengthening the temporalis muscle and removing any bony fusion with the base of the skull. Becausethe muscle does not have a tendon of origin or insertion, it cannot be lengthenedby tenotomy. Although the fusion of the coronoidprocesswith the zygomatic arch is not often seen,the invariable presenceof the contracted temporalis muscle makes removal of the coronoid processmandatory in every caseof TMJ arthroplasty. We also observedthat excision of the coronoid processincreasesthe range of motion of the mandible immediately after surgery. In addition, in the patients with reankylosis after isolated condylectomy,condylectomytogetherwith coronoidectomyhas resulted in excellent range of motion. With one exception, in our caseswhere we routinely combinethe excisionof the condylewith the coronoid, no reankylosis has occurred.’ Hence excision of the coronoid processis mandatory in all T M J arthroplasties. In the casesreported by Row2 coronoidectomy was added in some of the cases,with good results. Even in TMJ replacementarthroplasties, excision of the coronoid has been part of the procedure.3In the surgical procedureswhere simultaneouscorrection of thefacialasymmetryisdonetogetherwithTMJarthroplasty,4the excisedboneincludesthe coronoidprocess as well. The fusion of coronoidwith the zygomatic arch has not posedany problem in the excisionof the coronoid; becausethe massof boneis small, we simply divide the coronoid process at the lower border of zygomatic arch. When the condylar bone mass is fused with the tympanic plate posteriorly, the fusion has to be
TMJ ankylosis
663
divided carefully without damaging the external auditory meatus. Becausethe area of fusion is superficial, the eardrum has never been damaged. The condylar bone mass has always been excised subperiosteally,without a surgical problem, because there was no fusion of the bonemassmedially with the lateral pterygoid plate. The pterygoid venousplexus, if carefully dissected,is not injured. We had only one serioushemorrhagethat required external carotid ligation. If bleedingoccurs before delivering the coronoid process, one may fracture the condylar mass from the coronoid at the mandibular notch with a bone lever and pack the hemorrhagic bed. This has always been adequateto control the extremely rare m inor hemorrhagesin our seriesof cases. The growth of bone between the condyle and condylar fossa in intra-articular bony ankylosis is a phenomenonseen elsewherein the body. However, the juxta-articular mass of bone in the traumatic group is unusual. It is thought to be somewhatsimilar to myositis ossificanstraumatica, which is often seen in the posttraumatic elbows, where there is an osseousbridging without affecting the joint anatomy. The trauma that results in an ankylosis of TMJ usually occurs early in childhood. The TMJ cannot be easily immobilized in children. Thereforethe myositic mass grows in the juxta-articular tissuesand results in variable sizesof the mass of bone. From the published literature it appearsthat India has a high incidenceof juxta-articular ankylosis of TMJ ankylosis. The reason is not clear. The remodelingof the mandible after surgery, especially in patients with unilateral ankylosis,is a phenomenonthat has no parallel elsewherein the body. The remodelingis maximal if the ankylosedTMJs are surgically treated early in childhood. This is contrary to a belief that operation early in childhood is likely to retard growth. The growth of the mandible after condylectomy and coronoidectomy has never decreasedin our cases.Freeduset a1.5reconfirmedthat no epiphysealcenter exists in the condyle of the mandible, therefore excision of the condyle doesnot alter the growth of the mandible. They supportedthe concept of “functional space” put forth by Moss and Salantijn.‘j The restoration of mobility and normal muscle action after TMJ arthroplasty maintains the “functional space”; hence there is the tendency for correction of the facial deformity. As mentionedpreviously, early surgery also prevents severe dental malocclusionsand malalignment.Therefore,however young the patient is, the releaseof all three ankylosing elements,the condyle, coronoid process,and temporalis muscle,providesbetter results in terms of both movementand modeling of the face.
664
Sauna and Dave
0~4~
SL,KG OKAI
MOD ORAL PAI HOI
December I 99 1 REFERENCES 1. Chandra P, Dave PK. Temporomandibular joint ankylosis: progress in clinical and biological research. Vol 187: In: Dixon A, Sarnat BG, ed. Normal and abnormal bone growth: basic and clinical research. New York: Alan R Liss, 1985;449-58. 2. Row NL. Ankylosis of temporomandibular joint. J R Coll Surg Edin 1982;27:67-79, 167-73, 209-18. 3. Kent JN, Block MS, Homsy CA, Prewitt JM III, Reid R. Experience with a polymer glenoid fossa prosthesis for partial and total temporomandibular joint reconstruction. J Oral Maxillofac Surg 1986;44:520-33. 4. Munro IR, Chen YR, Park BY. Simultaneous total correction of temporomandibular ankylosis and facial asymmetry. Plast Reconstr Surg 1986;77:5 17-27.
5. Freedus MS, William DZ, Doyle PK. Principle of treatment of temporomandibular joint ankylosis. J Oral Surg 1975: 33:757-65. 6. Moss ML, Salantijn L. The capsular matrix. Am J Orthod 1969:56:474-90. Reprint requests. U. C. Sarma Department of Orthopaedics All-India Institute of Medical Sciences New Delhi 110029, India
OF ORTHOPAEDICS,
ALL-INDIA
INSTITUTE
OF MEDICAL
SCIENCES
Seventy-five condylectomy and coronoidectomy specimens of temporomandibular joint ankylosis in 61 patients were studied. Fourteen patients had bilateral ankylosis, six of whom had fibrous ankylosis on one side. There were two types of ankyloses: intra-articular and juxta-articular. Intra-articular ankylosis was seen only in reankylosis or in postinfective cases. Sixty-six cases were posttraumatic juxta-articular ankylosis. A rudimentary temporomandibular joint with an atrophic condylar articular surface was found in all juxta-articular ankyloses. The size of new bone in the specimens varied from 0.5 to 3 cm. Fusion of the extra-articular bone mass with tympanic plate was also observed. Contracture of temporalis muscle was noted in all the cases, which made excision of the coronoid processes mandatory in all the arthroplasties. Arthroplasty early in childhood did not hamper growth; instead, facial remodeling was enhanced. (ORAL SURG ORAL MED ORAL PATHOL 1991;72:660-4)
T
emporomandibular joint (TMJ) ankylosis is not uncommon in India. These patients, usually of lower socioeconomicstatus, are seenat varied intervals after the onset of the disease,which is usually early in childhood. Eating is difficult, and patients rely mostly on having the food pushedthrough the vestibule of the mouth and then behind the last molar teeth. Oral hygiene is poor. The treatment of this condition is surgical. The pathologic changes encountered in this ankylosis dependson the cause of the diseaseand in most casesa distinct correlation is possible.A knowledge of the pathologic anatomy of this crippling diseaseis essential to explain the strategy of the treatment and to avoid complication in this relatively difficult but rewarding surgery. The purpose of this article is to highlight the pathologic anatomy of this condition and to correlate it with the etiologic conditions. MATERIAL
AND METHODS
Since the mid- 1960sthe orthopedic surgeonsof the All-India Institute of Medical Sciences have been performing condylectomy and coronoidectomy for TMJ ankylosis with excellent results. The method of treatment and the results of surgery have been published by Chandra and Dave.’The entire bone mass, 7/12/29899
660
Fig. 1. Specimens excisedfrom bilateral TMJ ankyloses. Left, Specimens from patient with bilateral bony ankylos-
es. Right, Fibrous ankylosis in one side (inner specimen).
consisting of the condyle, the coronoid process,and the new bone, was removed in one block subperiosteally and preservedfor postoperative studies. Of 206 cases surgically treated, 75 specimensfrom 61 patients were available for study. This included three casesof interposition arthroplasty that had reankylosed. The gross pathologic findings were noted, the amount of extra bone measuredand the status of the joint surfaces noted. The size and shape of the coro-
Volume 72
Number6
Fig. 2. Computerizedaxial tomographof patient with bilateralTMJ ankylosis.Note sizeof juxta-articularbone. Atrophiccondyle(arrow) is seenseparatefrom newbone. Juxta-articularbonemassshowsevidenceof pseudoarthrosis (broken arrow). However,at surgerywe nevernoticed pseudoarthrosis.
noid processwas examined and observedfor any evidence of new bone formation. These were supplementedwith operativeand clinical observationswherever necessary. OBSERVATION
The ankylosis was bilateral in 14 patients, and the remaining 47 had unilateral ankylosis: 22 on the left side and 25 on the right. There was a total of 69 bony ankylosesand six fibrous ankyloses(Fig. 1). Fibrous ankylosis was found on only one side of some of the bilateral ankylosis patients; that is, 8 of the 14 bilateral ankyloses involved bony ankylosis in both the joints and the other six involved bony ankylosisin one joint whereas the other joint had fibrous ankylosis. Primary fibrous ankylosis was not seenin any of the specimensexamined. The bony ankyloseswere of two types: intra-articular and juxta-articular. In the intra-articular type the bone extendedfrom one articular surface to the other, replacing both of them entirely; in the juxtaarticular type a variable massof bone extendedfrom the ramus of the mandible to the zygomatic arch, pushing the condylar articular surface medially. On computedtomographicscans,the TMJ demonstrated as a low-density line, giving an appearanceof pseudoarthrosis (Fig. 2). Intra-articular ankylosis was seen only in those caseswhich had reankylosed after some attempt at arthroplasty and in postinfectiveankylosis;nine specimens showed intra-articular ankyloses, of which
Fig. 3. Specimensfrom casesof reankylosisafter attemptedarthroplastywith siliconeelastomerballs(lefj and
silicone elastomer pulley (right). Note that one of balls (arrow) is completely incorporated in new bone mass.Silicone elastomer pulley also had same fate.
three followed attempted interposition arthroplasty (i.e., siliconeelastomerpulley, silver foil) (Fig. 3); five showedreankylosis after attempted excision arthroplasty by excisingthe condyleonly; one specimenwas probably causedby ear infection. The remaining 60 specimenswere of the juxtaarticular type. The agedistribution of this variety was uniform. The chin scar in most casesservedas a definite clue suggestingthe etiologic factor to be traumatic in these ankyloses.It is pertinent to mention here that 190 of the 206 surgically treated caseswere posttraumaticjuxta-articular ankylosis.The bridging massof bone betweenthe ramus of the mandible and the zygomatic arch had its maximum thicknessin the region of the condyleand then sharply narroweddown to merge imperceptibly with the ramus of the mandible about 2 cm below the zygomatic arch. The thicknessof this new bone was variable, 0.5 to 3 cm at the site of maximum diameter. The size of the bone mass dependedon the age and size of the mandible. It extended medially under the temporal fossatoward the lateral pterygoid plate but was never fused to the lateral pterygoid plate becauseof the attachmentsof the pterygoid muscles. Anteriorly the bone mass sometimes extendedpast the mandibular notch to the medial side of the coronoid process. Posteriorly, it extendsup to the tympanic plate; the fusion of bone mass with the latter was observedin 12 specimens (Fig. 4). In the juxta-articular types the condyle was atrophic and was pushed medially, anteromedially, or posteromedially.It retained its attachment to lateral pterygoid muscle despite the altered locations. In at
662
Sarma and Dave
ORAL SURG ORAL M E D ORAL PATHOL
December I99 I
Fig. 4. Massive juxta-articular bone that had fused with tympanic plate.
Fig. 5. Specimenswith varying degreesofjuxta-articular bone. Upper pair shows condyle (arrow) and bone mass separate from each other. Middle pair displays condylar articular surface in the samemassof bone but at lower level. Lowerpair showscompletefusion of condyle with new bone, the former being demarcated by remnants of articular cartilage only.
least 50% of the cases, usually in children, an attenuated disk was present, signifying the intact joint and the juxta-articular ankylosis. The condylar articular surface was always covered by a thin layer of articular cartilage. Its size was variable and seen in an oval, semilunar, or crescent shape. The capsule on the lateral aspect of the affected joint could not be identified even at operation, although a rudimentary synovial joint persisted between the altered condylar articular surface and condylar fossa. In sharp contrast to the findings in the juxta-articular types, in the intra-articular types of ankyloses, the condyle disappeared completely as a result of surgery or disease, no articular surface was identifiable, and the bone mass was often smaller, In fibrous anky-
Fig. 6. Specimen from intra-articular ankylosis, where bone mass is smaller and remnant of condyle is not seen.
loses the condyles remained intact, although they were atrophic and the articular cartilage, as in other joints with fibrous ankylosis, was degenerated and was replaced by fibrous tissue. The coronoid process, although of variable size, was well preserved. This remained separated from the juxta-articular mass of bone. The outer surface of the coronoid process was fused with inner surface of zygomatic arch in two specimens. Although not included in this group of specimens, rarely have we seen bone as a single mass extending from the tympanic plate to the anterior border of the coronoid process, thus converting the tympanic plate, zygomatic arch, condyle, and coronoid process into a single mass of bone. The temporalis muscle, although maintaining its normal attachments both above and below and retaining its normal contractile muscular element, was secondarily contracted as a result of prolonged duration of the ankyloses. The masseter muscle was contracted in an identical way. Overall, the mandibles were smaller and at times grossly retracted. In the unilateral cases the chin was deviated to the affected side. The increased depth of the pregonial notch in the affected side was a diagnostic, radiographic and clinical finding. Dental malocclusion and poor alignment of teeth were invariably found in all cases of TMJ ankylosis. All these changes were secondary and were evidences of the presence of the ankylosis during the period of growth. DISCUSSION
Ankylosis of the TMJ has extensive secondary effects. These secondary changes are cosmetically important, of course, but the overriding surgical significance is the problem of postoperative reankylosis and the preservation of an adequate range of motion in the
Volume 72 Number 6
affected joint. The most important of the secondary effects are the contractures of the temporalis and massetermuscles.Unless these contractures are relieved, arthroplasty will be unsuccessful.The other secondary change of surgical significance is the fibrous ankylosis of the oppositeTMJ. The deviation of the chin, the regressionof the mandible, the facial asymmetry and the dental malocclussiontend to revert to normal as the postoperativenormal excursions of the mandible are reestablished.Hence the earlier the operation, the better the prognosis. It is evident from the pathologic anatomy of the ankylosedjoint that three factors prevent mobility in the joint: the bridging bonemassbetweenthe condyle and condylar fossa, the contracted muscles,and the occasionalfusion of the coronoid processwith zygomatic arch. It is imperative that all three be corrected concurrent with an arthroplasty of the joint. Failure to do so results in reankylosisor in lim ited successof the procedure.The removal of the coronoidprocessin addition to the condylar massof bone servestwo purposes:effectively lengthening the temporalis muscle and removing any bony fusion with the base of the skull. Becausethe muscle does not have a tendon of origin or insertion, it cannot be lengthenedby tenotomy. Although the fusion of the coronoidprocesswith the zygomatic arch is not often seen,the invariable presenceof the contracted temporalis muscle makes removal of the coronoid processmandatory in every caseof TMJ arthroplasty. We also observedthat excision of the coronoid processincreasesthe range of motion of the mandible immediately after surgery. In addition, in the patients with reankylosis after isolated condylectomy,condylectomytogetherwith coronoidectomyhas resulted in excellent range of motion. With one exception, in our caseswhere we routinely combinethe excisionof the condylewith the coronoid, no reankylosis has occurred.’ Hence excision of the coronoid processis mandatory in all T M J arthroplasties. In the casesreported by Row2 coronoidectomy was added in some of the cases,with good results. Even in TMJ replacementarthroplasties, excision of the coronoid has been part of the procedure.3In the surgical procedureswhere simultaneouscorrection of thefacialasymmetryisdonetogetherwithTMJarthroplasty,4the excisedboneincludesthe coronoidprocess as well. The fusion of coronoidwith the zygomatic arch has not posedany problem in the excisionof the coronoid; becausethe massof boneis small, we simply divide the coronoid process at the lower border of zygomatic arch. When the condylar bone mass is fused with the tympanic plate posteriorly, the fusion has to be
TMJ ankylosis
663
divided carefully without damaging the external auditory meatus. Becausethe area of fusion is superficial, the eardrum has never been damaged. The condylar bone mass has always been excised subperiosteally,without a surgical problem, because there was no fusion of the bonemassmedially with the lateral pterygoid plate. The pterygoid venousplexus, if carefully dissected,is not injured. We had only one serioushemorrhagethat required external carotid ligation. If bleedingoccurs before delivering the coronoid process, one may fracture the condylar mass from the coronoid at the mandibular notch with a bone lever and pack the hemorrhagic bed. This has always been adequateto control the extremely rare m inor hemorrhagesin our seriesof cases. The growth of bone between the condyle and condylar fossa in intra-articular bony ankylosis is a phenomenonseen elsewherein the body. However, the juxta-articular mass of bone in the traumatic group is unusual. It is thought to be somewhatsimilar to myositis ossificanstraumatica, which is often seen in the posttraumatic elbows, where there is an osseousbridging without affecting the joint anatomy. The trauma that results in an ankylosis of TMJ usually occurs early in childhood. The TMJ cannot be easily immobilized in children. Thereforethe myositic mass grows in the juxta-articular tissuesand results in variable sizesof the mass of bone. From the published literature it appearsthat India has a high incidenceof juxta-articular ankylosis of TMJ ankylosis. The reason is not clear. The remodelingof the mandible after surgery, especially in patients with unilateral ankylosis,is a phenomenonthat has no parallel elsewherein the body. The remodelingis maximal if the ankylosedTMJs are surgically treated early in childhood. This is contrary to a belief that operation early in childhood is likely to retard growth. The growth of the mandible after condylectomy and coronoidectomy has never decreasedin our cases.Freeduset a1.5reconfirmedthat no epiphysealcenter exists in the condyle of the mandible, therefore excision of the condyle doesnot alter the growth of the mandible. They supportedthe concept of “functional space” put forth by Moss and Salantijn.‘j The restoration of mobility and normal muscle action after TMJ arthroplasty maintains the “functional space”; hence there is the tendency for correction of the facial deformity. As mentionedpreviously, early surgery also prevents severe dental malocclusionsand malalignment.Therefore,however young the patient is, the releaseof all three ankylosing elements,the condyle, coronoid process,and temporalis muscle,providesbetter results in terms of both movementand modeling of the face.
664
Sauna and Dave
0~4~
SL,KG OKAI
MOD ORAL PAI HOI
December I 99 1 REFERENCES 1. Chandra P, Dave PK. Temporomandibular joint ankylosis: progress in clinical and biological research. Vol 187: In: Dixon A, Sarnat BG, ed. Normal and abnormal bone growth: basic and clinical research. New York: Alan R Liss, 1985;449-58. 2. Row NL. Ankylosis of temporomandibular joint. J R Coll Surg Edin 1982;27:67-79, 167-73, 209-18. 3. Kent JN, Block MS, Homsy CA, Prewitt JM III, Reid R. Experience with a polymer glenoid fossa prosthesis for partial and total temporomandibular joint reconstruction. J Oral Maxillofac Surg 1986;44:520-33. 4. Munro IR, Chen YR, Park BY. Simultaneous total correction of temporomandibular ankylosis and facial asymmetry. Plast Reconstr Surg 1986;77:5 17-27.
5. Freedus MS, William DZ, Doyle PK. Principle of treatment of temporomandibular joint ankylosis. J Oral Surg 1975: 33:757-65. 6. Moss ML, Salantijn L. The capsular matrix. Am J Orthod 1969:56:474-90. Reprint requests. U. C. Sarma Department of Orthopaedics All-India Institute of Medical Sciences New Delhi 110029, India
