prevalence of morphological changes in the surfaces of the

J Oral Maxillofac Surg

56339-343, 1998

Prevalence of Morphological Changes in the Surfaces of the Temporomandibular

Joint Disc Associated With Internal Derangement

Toshirou Kondoh, DMD, PbD, * Per-Lennart Westesson, MD, DDS, PbD, f

Tetsu Takahashi, DDS, PhD,f and Kan-i&i Seto, DDS, PbDJ

Purpose: The purpose of this study was to determine the prevalence of morphological changes in the superior and inferior surfaces in the temporomandibular joint (TMJ) disc and relate them to disc displacement.

Materials and Methods: Thirty TMJs obtained from fresh cadavers were studied. The TMJs were dissected, and the superior and inferior surfaces of the disc were inspected and classified as intact, irregular, or perforated. These findings were correlated to the position of the disc.

Results: There was a greater prevalence of morphologic changes in the inferior (57%) than in the superior surface (17%) of the disc (P < .OOl). This was found for joints both with normal disc position and those with disc displacement. There was no relationship between surface irregularities of the inferior surface and the position of the disc. Perforation was seen more frequently in joints with disc displacement than in those with normal disc position.

Conclusion: Morphologic changes in the inferior surface of the TMJ disc are more prevalent than those in the superior surface, but this is not related to disc position. However, this needs to be considered when doing arthroscopy of only the superior joint compartment.

Disc displacement is the morphologic alteration of the temporomandibular joint (TMJ) most commonly en- countered when patients with signs and symptoms of temporomandibular disorders are examined.’ Most frequently the disc is displaced anteriorly, but there is also high incidence of medial or lateral displacement, as well as a combination of displacement.2,s

Gross comparison of the morphologic appearance of normal joints with that of joints with disc displacement has also suggested that disc displacement is the predisposing factor that leads to degenerative changes

*First Department of Oral and Maxillofacial Surgery, School of

Dentistry, Tsurumi University, Tsurumi-ku, Yokohama, Japan.

tDepartment of Radiology, School of Medicine, Iiniversity of

Rochester, Rochester NY.

*Department of Oral and Maxillofacial Surgery, School of Medi-

cine, Akita University, Hondo Akita, Japan.

SFirst Department of Oral and Maxillofacial Surgery, School of

Dentistry, Tsurumi University, Tsurum-ku, Yokohama, Japan.

Address correspondence and reprint requests to Dr Kondoh: First

Department of Oral and Maxillofacial Surgery, School of Dentistry,

Tsurumi University, 2-l-3 Tsurumi Tsurumi-ku, Yokohama, Japan,

0 1998 American Association of Oral and Ma&facial Surgeons

0278.2391/98/56030010$3.00/0

of the articular surfaces and perforation of the disc or posterior attachment.* However, another study suggested the opposite causative relation.5

In our examination of the TMJ with a thin-needle arthroscope, we have observed that morphologic changes are more common in the inferior than in the superior joint compartment.6,7 The clinical impression of more irregularities of the inferior than of the superior surface of the disc has been supported by a study by Kirk.* If there is a greater incidence of morphologic alteration in the inferior compartment, there is a risk of underestimating the degree of abnormality when arthroscopic instruments are in- serted only into the superior joint compartment. The purposes of this study were to systematically compare the morphologic appearance of the superior and inferior surfaces of the disc and to examine the correlation of these findings to disc position.

Materials and Methods

Thirty randomly selected left TMJs were removed as blocks from fresh cadavers during autopsy. The mean age at the time of death was 75 years, with a range of 45 to 95 years. There was no information available on possible TMJ symptoms before death.

The TMJs were dissected as previously described.6

339

340 PREVALENCE OF CHANGES IN THE SURFACES OF THE DISC

The superior and inferior joint compartments were opened in the medial, anterior, and lateral aspects. The superior and inferior surfaces of the disc could then be inspected without disturbing the posterior disc attachment. In this way, the position of the disc could be evaluated in relation to the mandibular condyle and glenoid fossa without separation of the two joint compartments. The articular surfaces of the condyle and temporal joint components were also inspected macroscopically.

The morphologic appearance of the disc surfaces was classified as normal with intact, smooth surface (Fig l), irregular (Fig 2) or perforated (Fig 3, Table 1). The category of perforated disc in this study consisted of perforation at the disc proper or the posterior disc attachment. The appearance of the articular surfaces of the temporal joint component and condyle was also classified as normal (intact and smooth), remodeling, or degenerative changes. When different morphologic changes were found in dilfer- ent parts of the joint, the most abnormal of the findings was recorded. The presence of disc displacement was determined according to previously described criteria.9 The type of disc displacement, such

FIGURE 2. A, Anterior view of the superior surface of a disc showing irregularities (arrows]. 5, Inferior surface of a disc showing irregular

surface with fissures, pits [arrow], and small elevations (arrowheads).

as anterior, medial, lateral, or combination, was recorded.

FIGURE 1. A, Anterior view of the superior surface of the disc showing a normal surface. 6, Inferior surface of the same disc showing a normal surface.

Results

Morphologic alterations were seen in the superior surface of the disc in 14 joints (nine perforations and five surface irregularities). The inferior surface showed morphologic alterations in 26 joints (nine perforations and 17 surface irregularities). The prevalence of morphologic changes was significantly higher in the inferior than in the superior surface of the disc (x2 = 32.2, P < .OOl). The morphologic changes of the disc surfaces were commonly located in the lateral third of the joint (Fig 4). Disc perforation, seen in nine joints, was more frequently present when there was disc displacement than when there was normal disc position (x2 = 16, P < .OOl, Table 2). The disc was located normally in 16 joints (53%) and displaced in the remaining 14 joints (47%).

The condition of the articular surfaces of the temporal compartment and condyle relative to disc position is shown in Table 3. Remodeling was equally distributed in the two groups of joints, but degenerative changes were seen only in the joints with disc displacement. The morphologic changes were most commonly located in the lateral third of the joint (Fig 4).

KONDOH ET AI

FIGURE 3. A, Anterior view of the superior surface of a disc showing perforation [arrows) at its lateral portion. 5, Inferior surface of the same disc showing the perforation (arrows) in the lateral part.

Discussion

This study showed a significantly higher incidence of morphologic changes of the inferior than of the superior surface of the TMJ disc. This is in accordance with an investigation by Kirk,8 who studied the TMJ disc in patients with chronic internal derangement. In addition, he studied joints with normal disc position

Superior and inferior surfaces of disc Normal: Smooth, intact surface without

irregularities Irregular surface: Uneven, irregular surface with

fissures or elevations Perforation: Communication between inferior

and superior joint spaces through disc or retrodiscal tissue

Articular surface of condyle and temporal component Normal: Smooth intact surface without

irregularities Remodeling: Deviation in form with an intact

articular soft tissue cover Degenerative changes: Breakage of soft tissue covering

with exposure of bone with or without deviation in form

FIGURE 4. Distribution of findings for the articular surfaces [A, anterior; P, posterior; L, lateral; M, medial; NL, normal smooth intact surface; IRS, irregular surface; PF, perforation; RMD, remodeling; DGR, degenerative change).

and found the same pattern of morphologic alterations. It was interesting to note that the prevalence of abnormalities of the inferior surface of the disc was higher than that of the superior surface both in joints with normal disc position and in those with disc displacement.

In earlier work,* we attributed the surface irregularities to disc displacement and, in accordance with previous studies, the finding of perforation and degenerative changes were predominantly in joints with disc displacement. lo-l4 This indicates that perforation and degenerative joint disease are, in most cases, secondary to disc displacement.15

Other studies have shown degenerative changes tiecting the articular surfaces in 50% of TMJs with normal disc position.5 Our observations also indicate that surface irregularities do not always lead to disc displacement. The findings of a high prevalence of irregularities of the inferior surface of the disc in normal joints indicates that this may occur without disc displacement. In this study, three cases of perforation were observed in the group with normal disc position (Table 2). These perforations were located in the disc proper, which is different from perforations in the posterior disc attachment associated with disc displacement.16~17

The relationship between disc surface irregularities and disc displacement may not be as simple as previously thought, and further studies are needed to fully understand the relationship between remodeling, disc displacement, and degenerative changes.

Previous macroscopic studies of the TMJ have categorized the findings into normal, remodeling, or degenerative changes. l* Remodeling has also been termed deviation in form. Deviation in form is defined as remodeling that does not reach the stage of degenerative change (osteoarthritic changes), and it

342 PREVALENCE OF CHANGES IN THE SURFACES OF THE DISC

Normal Superior Disc Position (16 joints) Disc displacement (14 joints) Intact Smooth Irregular Intact Smooth IlXglllar

Surface Surface Perforation Surface SUrfaCe Perforation

Superior disc surface Inferior disc surface

NOTE. N = 30 joints.

12(75%) 4(25%)

1(6%) 3(19%) 9(56%) 3(19%)

(x2 = 16.6; P < .005)

4(29%) 0

4(29%) 6(43%) 8(57%) 6(439/o)

(x2 = 14.0; P < .Ol>

Temporal articular surface Condylar articular surface

Normal Superior Disc Position (16 Joints) Disc Displacement (14 joints) Intact Smooth Irregular Intact Smooth Irregular

Surface Surface Degeneration SmCe Surface Degeneration

10(63%) 6(37%) 0 7(50%) 4(29%) 3(21%) 7(44%) 9(56%) 0 2(14%) 8(57%) 4(29%)

NOTE. N = 30 joints.

has been considered as a physiologic adaptation to changes in stress and function of the joint.ls,19 An- other light microscopic study5 has included remodeling in the classification of degenerative changes. It is obvious that remodeling will be present in many joints with degenerative changes, but as long as the articular surface is intact. We regard macroscopic remodeling as a physiologic adaptation to alteration in function and reserve the term degenerative change for those instances in which the articular surface had been disrupted and there is exposure of bone.

Remodeling of the disc has usually been associated with thinning, whereas perforation has been considered a sign of degenerative change.1*,20 These distinc- tions are obviously arbitrary, but were based on earlier work on morphologic changes of the TMJ.zl In addition to deviation in form or thinning, we used surface irregularity in the classification of disc alterations in this study. This probably corresponds to grade I (unevenness) that was used by Oberg in his classic study.21

The subjects investigated in this study were rela- tively old (mean age, 75 years). The appearance of irregularities of the disc surface may therefore reflect the effect of aging rather than disease. Several investi- gators have reported age-related increases in remodeling and degenerative changes in the various components of the TMJ. 4,5,22,23 However, remodeling is also present in younger individuals, and the relationship to age is not fully understood.20

We found a 47% incidence of disc displacement in the 30 joints studied. This is consistent with earlier studies* and with the increase in age.21 It was initially anticipated that the incidence of morphologic change of the inferior surface of the disc would be associated with disc displacement. However, this was not the

case, because surface irregularities also were seen in those joints with normal disc position. The splitting or fissuring on the inferior surface of the disc may be an early stage of perforation.24

References

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Paesani D, Westesson PL, Hatala M, et al: Prevalence of temporomandibular joint internal derangement in patients with craniomandibular disorders. Am J Orthod Dentofacial Orthop 101:41, 1992 Tasaki MM, Westesson PL: Temporomandibular joint: Diagnos- tic accuracy with sagittal and coronal MR imaging. Radiology 186:723, 1993 Brooks SL, Westesson PL: Temporomandibular joint: Value of coronal MR images. Radiology 188:317, 1993 Westesson PL, Rohlin M: Internal derangement related to osteoarthrosis in temporomandibular joint autopsy specimens. Oral Surg Oral Med Oral Path01 57:17, 1984 de Bont LG, Boering G, Liem RS, et al: Osteoarthritis and internal derangement of the temporomandibular joint: A light microscopic study. J Oral Maxillofac Surg 44:634, 1986 Kondoh T, Westesson PL: Diagnostic accuracy of temporomandibular joint lower-compartment arthroscopy using an ultrathin arthroscope: A postmortem study. J Oral Maxillofac Surg 49:619, 1991 Kondoh T, Westesson PL: Ultrathin arthroscope for use in the lower compartment of the temporomandibular joint. Oral Surg Oral Med Oral Path01 72: 146,199l Kirk WS Jr: Morphologic differences between superior and inferior disc surfaces in chronic internal derangement of the temporomandibular joint. J Oral Maxillofac Surg 48:455, 1990 Westesson PL, Rohlin M: Diagnostic accuracy of double- contrast arthrotomography of the temporomandibular joint: Correlation with postmortem morphology. AJR 143:655, 1984 Wilkes CH: Structural and functional alterations of the temporomandibular joint. Northwest Dent 57:287, 1978 Wilkes CH: Arthrography of the temporomandibular joint in patients with the TMJ pain-dysfunction syndrome. Minn Med 61:645, 1978 Farrar WB, McCarty WL Jr: Inferior joint space arthrography and characteristics of condylar paths in internal derangements of the TMJ. J Prosthet Dent 41:548, 1979 Katzberg RW, Dolwick MF, Helms CA, et al: Arthrotomography of the temporomandibular joint. AJR 134:995, 1980

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14. Eriksson L, Westesson PL: Clinical and radiological study of patients with anterior disc displacement of the temporomandibular joint. Swed Dent J 7:55, 1983

15. Wilkes CH: Internal derangements of the temporomandibular joint: Pathological variations. Arch Otolaqngol Head Neck Surg 115:469, 1989

16. Scapino RP: Hlstopathology associated with malposition of the human temporomandibular joint disc. Oral Surg Oral Med Oral Path01 55:382, 1983

17. Stegenga B, de Bont LG, Boering G, et al: Tissue responses to degenerative changes in the temporomandibular joint: A re- view. J Oral Maxillofac Surg 49:1079, 1991

18. Hansson T, Oberg T: Arthrosis and deviation in form ln the temporomandlbular joint: A macroscopic study on a human autopsy material. Acta Odontol Stand 35:167, 1977

19. Axelsson S, Fitins D, Hellsing G, et al: Arthrotic changes and deviation in form of the temporomandibular joint: An autopsy study. Swed Dent J 11:195, 1987

20. Solberg WK, Hansson TL, Nordstrom B: The temporomandibular joint in young adults at autopsy: A morphologic classilica- tion and evaluation. J Oral Rehabil 12:303, 1985

21. Oberg T, Carlsson GE, Fajers CM: The temporomandibular joint: A morphologic study on a human autopsy material. Acta Odontol Stand 29:349, 1971

22. Pereira FJ Jr, Lundh H, Westesson PL: Morphologic changes in the temporomandibular joint in different age groups: An autopsy investigation. Oral Surg Oral Med Oral Path01 78:279, 1994

23. Widmalm SE, Westesson PL, Kim IK, et al: Temporomandibular joint pathosis related to sex, age, and dentition in autopsy material. Oral Surg Oral Med Oral Path01 78:416, 1994

24. Kurita K, Westesson PL, Sternby NH, et al: Histologic features of the temporomandibular joint disk and posterior disk attachment: Comparison of symptom-free persons with normally positioned disks and patients with internal derangement. Oral Surg Oral Med Oral Path01 67:635,1989

J Oral Maxillofac Surg 56:343-344, 1998

Discussion

Prevalence of Morphological Changes in the Surfaces of the Temporomandibular Joint Disc Associated With Internal Derangement

William S. Kirk, Jr, DDS Private Practice, Charlotte, North Carolina

It is gratifying to see independent laboratory studies

confirm surgical observations to a degree of statistical

significance. With this article, I believe the authors have raised significant questions about diagnosis, clinical applica- tion, and surgical management.

At times, it appears as though the current understanding of painful temporomandibular joint (TMI) derangement is that it involves only a linear, forward, and medial displacement of an independently functioning disc. This article reminds us that there are 4 three-dimensional articular surfaces within every TMJ where pathology capable of creating pain and dysfunction may be found.

As suggested in this article and others investigating imaging characteristics of asymptomatic joints, it is evident that disc displacement is not necessarily associated with pain or dysfunction. It has been shown that there can be significant differences between adaptive remodeling and degenerative arthrosis in the superior or inferior compartments of the joint. It is my personal experience that operated joints almost always exhibit inflammatory disease or other pathology in the inferior compartment that is more advanced than that seen in the superior compartment, and these findings cannot be explained by the concept of disc displacement or destabilizing superior compartment adhe- sions.1,2 The authors also stress that these changes in the inferior compartment are seen with nondisplaced discs. I believe this to be an important point, because it expands the

concept of a potentially significant degenerative disease process beyond that caused by simple disc displacement.

This article raises several important questions that must be considered:

1. Are advancing stages of inferior compartment pathology capable of creating significant orthopedic dysfunction?

2. Is the type of tissue destruction reported in this article and others capable of creating acute and chronic synovitis, capsulitis, joint edema, and other painful destructive intlamma- tory conditions similar to those seen in other synovial joints of the body?

3. Are these conditions and associated inflammatory components a more biologically sound explanation for the pain and dysfunction than the psychosomatic models suggested by the National Institute of Health reports and insurance compa- nies,* or the “occlusionist” models used in the past to describe what has been assumed to be a heterogenous group of disorders?

I f the answers to these questions are simply “probably” or “possibly,” then any nonsurgical or surgical therapy must in some way acknowledge and address these conditions, which are irrefutable by their demonstrated presence.

This article also addresses the location of inferior compart-

ment disease. As noted in Figure 4, there was a predomi- nence of remodeling and pathology found in the lateral aspect of the joint involving the condylar surface, the disc/capsule surfaces, and the glenoid fossa. These phenom- ena have also been reported by Pipers and Moses.6 I believe that the TMJ mirrors other synovial joints, with the potential for development of a significant lateral compartment entrap- ment phenomenon. One must consider the possibility of significant encroachment on the lateral joint space by osteophytic disease along the lateral rim of the glenoid fossa, the lateral slope of the articular eminence, the lateral condylar surface, or the lateral disc/capsule surfaces. It is quite likely that once these processes begin, they are

prevalence of morphological changes in the surfaces of the

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