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Diagnostic accuracy of the ultrathin arthroscope for temporomandibular joint osteoarthrosis: Comparison of arthroscopic and histologic findings in a sheep model
J Oral MaxillofacSurg 52:278-281,1994
Diagnostic Accuracy of the Ultrathin Arthroscope for Temporomandibular Joint Osteoarthrosis: Comparison of Arthroscopic and Histologic Findings in a Sheep Model KENICHI KURITA, JUN-ICHI ISHIMARU,
DDS, PHD,* NOBUMI OGI, DDS, PtiD,t DDS,t AND YUJIRO HANDA, DDS, PHD$
The diagnostic accuracy of the ultrathin arthroscope was evaluated by examination of the superior joint space of the left temporomandibular joint in 20 sheep. At the time of induction of osteoarthrosis all joints were found to be normal. Six months later the arthroscopic examination was repeated and the results compared with the histologic examination. Similar findings were seen in 11 joints (55O), with arthroscopic overdiagnosis in two (10%) and underdiagnosis in seven (35%). Eight of 16 (50%) disc perforations were found. It was concluded that underdiagnosis occurred because the whole joint space cannot be examined atthroscopically and fibrillated tissue masks bone exposure.
systematically compared with the histologic changes. Bosanquet and Goss’ and Goss and Bosanquet” reported that sheep are a useful model for temporomandibular joint research. Ishimaru and Goss” succeeded in inducing osteoarthrosis in the sheep temporomandibular joint. In this study the superior compartment of the sheep temporomandibular joint with induced osteoarthrosis was viewed with an ultrathin arthroscope (diameter, 1.1 mm) to compare the arthroscopic and histologic findings.
Since its introduction,’ arthroscopy of the temporomandibular joint has been found useful in the diagnosis and treatment of temporomandibular joint disorders.2-6 An advantage of arthroscopy is the ability to detect early superficial changes in the osseous components that are not shown by magnetic resonance imaging or radiography.’ Quinn’ described chondromalacia, or softening of articular cartilage, using arthroscopy. However, the diagnostic accuracy of the arthroscopic findings for osteoarthrosis has not been
* Associate Professor, The Second Department of Oral and Maxillofacial Surgery, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan. f Visiting Researcher, Oral and Maxillofacial Surgery Unit, The University of Adelaide, Adelaide, Australia. $ Senior Lecturer, Department of Oral and Maxillofacial Surgery, Gifu University, Gifu, Japan. Supported by Grant-in-Aid for Scientific Research (C) from the Ministrv of Education. Science and Culture, Japan (project no. 0567 1665). Address correspondence and reprint requests to Dr Kurita: The Second Denartment of Oral and Maxillofacial Surgery, Schooi of Dentistry, Aichi-Gakuin University, 2-11 Suemori, Chikusaku, Nagoya, 464 Japan.
0 1994 American Association of Oral and Maxillofacial Surgeons FIGURE 1. Shiko MS-6 1IS arthroscope.
02792391/94/5203-0011$3.00/0
278
279
KURITA ET AL
Table 1. Arthroscopic and Histologic Stages of Osteoarthrosis Stage
‘*able 3. Sensitivity, Specificity, and Redicthfe Vah4esof Arthroscopic Magnoeis of Perforation (%)
Description
Arthroscopic Stage
1
Fibrous surface without fibrillation Fibrillation of the surface layer Bone exposure Smooth surface and even thickness of fibrous layer Uneven thickness of the surface layer Bone exposure
2 3 Histologic Stage I II III
Materials and Methods
The instruments used in this study were a Shinko FV-3000 arthroscopic system and a Shinko MS-6 11S arthroscope (Shinko Optical Co, Ltd, Tokyo, Japan; Fig 1). The irrigation cannula and the outer sheath for the optical fibers of the arthroscope were 1.1 mm and .8 mm in diameter, respectively. The arthroscope had a 70” field of view in air. A IO-mL syringe containing normal saline solution was attached to the irrigation cannula. The image of the joint space was observed during the procedure using a color TV camera and monitor. Arthroscopic photographs were taken with a 35 mm SLR camera (Nikon F2 [Nikon Co, Tokyo, Japan]), using Kodak SOOf1600 ASA films (Eastman Kodak Co, Rochester, NY). The animals were adult Merino sheep, weighting about 60 kg. The left temporomandibular joint of 20 sheep was examined at the commencement and termination of a series of experiments creating intraarticular osteoarthrosis.’ ’ General anesthesia was induced with an injection of thiopentone sodium into the external jugular vein and maintained with isoflurane/ N20/02 through an orotracheal tube. The preauricular region was shaved and surgically draped. A preauricular skin incision was made to expose the lateral capsule of the temporomandibular joint. The arthroscope was introduced into the joint space through a small stab incision made with a no. 11 scalpel in the central part of the capsule. Constant irrigation with normal saline was maintained through a cannula of the arthroscope to remove air bubbles and blood and to distend the superior joint space. Under this pressure, the capsule Table 2. Accuracy of Arthroscopic Diagnosis of Perforation (n = 20) True negative False negative True positive False positive
50 100 100 33
Sensitivity Specificity Positive predictive value Negative predictive value
was sufficiently distended to allow the arthroscope to freely move in the joint space. The arthroscopic findings were recorded, following which the inferior joint space was opened and the fibrocartilage gently removed from the condyle to create osteoarthrosis.” The wound was closed in layers and antibiotics were administrated intramuscularly. At 6 months afier the initial operation, the sheep were reanethetized and the joint spaces were arthroscopically observed for the presence of perforation of the disc and osteoarthrotic changes on the artitular eminence and fossa. The arthroscopic findings on the bone were classified into three stages (Table 1) by one of authors (K.K). The sheep were killed by an anesthetic overdose after arthroscopic observation. The temporomandibular joints were then removed en bloc and fixed with formalin. The specimens were decalcified and sagittally sectioned from lateral to medial for histologic study. The histologic lindings were classified into three stages (Table 1) by one of authors (N.O.). The most advanced arthroscopic and histologic stages in each joint were compared. Results
Disc perforation was observed arthroscopically in eight joints. Histologic examination confirmed disc perforation in these eight joints, and in the lateral one third of eight additional joints. Thus, eight of 16 perforations were diagnosed arthroscopically, with a 50% sensitivity and 100% positive predictive value (Tables 2, 3). The correlation between the arthroscopic and histologic diagnosis with respect to osteoarthrotic changes on the temporal bone is presented in Table 4. Of the Table 4. Correlation Between ArthroscOpic and Histologic Diagnosis Histologic Diagnosis (Stage)
Arthroscopic Diagnosis
(Stage) 1 2 3 Total
I
II
III
Tot.4
1 1 1 3
2 I 0 9
0 5 3 8
3 13 4 20
280
FIGURE 2.
ULTRA ARTHROSCOPY
FOR OSTEOARTHROSIS
Arthroscopic stage 2 and histologic stage II joint. A, Fibrillation seen arthroscopically on the posterior slope of the eminence E, eminence; D, disc.
(whife arrow heads). B, The fibrous layer on the posterior slope of the eminence is uneven (bkzck arrows). c, condyle;
20 joints, 11 (55%) were diagnosed correctly on arthroscopic examination. Seven joints (35%) were arthroscopically underdiagnosed, and two joints ( 10%) were overdiagnosed. In the histologic stage I joint, one of three joints was accurately diagnosed with the arthroscope, whereas the other two joints were overdiagnosed. In the histologic stage II joints, seven of nine joints (78%) were diagnosed accurately, with underdiagnosis of two joints (22%); there was no overdiagnosis (Fig 2). In histologic stage III joints, only three of the eight joints (38%) were correctly diagnosed arthroscopically (Fig 3). The remaining five joints were all diagnosed as an arthroscopic stage 2 in which the bone exposure was obscured by the covering fibrillation. Discussion Recently Quinn’ reported arthroscopic and histologic evidence of chondromalacia in the temporomandibular joint. However, correlation between the arthroscopic and histologic findings was not made. This
FIGURE 3. (large arrows).
is because of the technical difficulties in removing osseous tissue as a block by arthroscopy and in identifying an arthroscopically viewed site with the histologic site, as well as important ethical issues in clinical research. Thus, in this study the arthroscopic and histopathologic findings were compared using experimentally induced osteoarthrosis in a sheep joint. Osteoarthrosis was commonly underdiagnosed arthroscopically in this study; only three of eight histologic stage III joints were correctly diagnosed. The remaining five joints were underdiagnosed as arthroscopic stage 2 because of massive fibrillation covering the bone exposure (Fig 4). In this experiment a probe was not used to avoid making scratch marks on the bony surface that would be difficult to distinguish from ostoarthrosis on histologic examination. If a probe had been used for palpation of the bony surfaces, the diagnostic accuracy in histologic stage III joints might have been higher. Therefore, when much fibrillation is seen arthroscopically in clinical cases, palpation of the bony surface under the fibrillation is recommended. Eight of 16 perforations diagnosed arthroscopically
Arthroscopic stage 3 and histologic stage III joint. A, Bone exposure seen arthroscopically on the posterior slope of the eminence B, Bone exposure on the posterior slope (smaN arrows). c, condyle; E, eminence; D, disc.
KURITA ET AL
FIGURE 4. Disagreement between arthroscopic and histologic diagnosis. A, Arthroscopicaily this joint was diagnosed stage 2 because of massive fibrillation (white arrow@, whereas in B, histologically, it was diagnosed as stage Ill because of bone exposure (hluck arron:v).
were all confirmed histologically. The eight perforations that were not seen arthroscopically were all located in the lateral one third of the joint space. This result, which supports previous reports,‘2*‘3 indicates that the whole joint space cannot be observed by a single arthroscopic approach. Therefore, an additional puncture from a different direction, such as an endaural approach, or an arthroscope with a different angle of view, is necessary to inspect the entire joint space. Compared with the previous reports using human cadavers,12.13 the sensitivity for recognition of temporomandibular joint disc perforation is high. This is partly because the upper space could be seen from anterior to posterior in all joints after the capsule was exposed because the joint space is flatter in sheep than in the human. The other reason was that arthroscopic examination was performed under general anesthesia on a live animal rather than on a cadaver, which is unyielding. It was possible in this experiment to insert the ultrathin 1.1-mm diameter arthroscope and examine the joint space in all cases. Because the size of the sheep temporomandibular joint is similar to that in humans, this scope also can be used for examination of human joint. The instrument has been used recently for arthroscopy of the lower compartment of human temporomandibular joints. I4515 Arthroscopic examination with the ultrathin scope is possible under local anethesia because of the minimal surgical intervention needed. It was concluded that the diagnostic accuracy for osteoarthrosis (55%) with an ultrathin arthroscope is clinically acceptable. Acknowledgment The authors thanks Professor Aiastair N. Goss, Oral and Maxillofacial Surgery Unit. the University of Adelaide, Australia. for research support.
References I. Ohnishi M: Arthroscopy of the temporomandibular joint. J Stomatol Sot Jpn 42:207, 1975 2. Murakami K, lto K: Arthroscopy of the temporomandibuiar joint. Arthroscopic anatomy and arthroscopic approaches in the human cadaver (in Japanese). Arthroscopy 6:1, 1981 3. Goss AN, Bosanquet AG: Temporomandibular joint arthroscopy. J Oral Maxiiiofac Surg 44:6 14, 1986 4. Sanders B: Arthroscopic surgery of the temporomandibuiar joint: Treatment of internal derangement with persistent closed lock. Oral Surg Oral Med Oral Pathol 62:361, 1986 5. Moses JJ, Sartoris D, Glass R, et al: The effect of arthroscopic surgical lysis and iavage of the superior joint space on TMJ disc position and mobility. J Oral Maxillofac Surg 47:674, 1989 6. Mongomery M, Sickels JEV, Harms S. et al: Arthroscopic TMJ surgery: Etfects on signs, symptoms, and disk position. J Oral Maxiliofac Surg 47: 1263, 1989 7. Israel HA, Ratciiffe A: Early diagnosis of osteoarthrosis of temporomandibuiar joint: Correlation between arthroscopic diagnosis and keratan sulfate levels in the synoviai fluid. J Oral Maxiliofac Surg 49:708. 1991 8. Quinn JH: Arthroscopic and histologic evidence of chondromalacia in the temporomandibuiar joint. Oral Surg Oral Med Oral Path01 70:387, 1990 9. Bosanquet A, Goss AN: The sheep as a model for temporomandibular joint surgery. lnt J Oral Maxiiiofac Surg 16:600, 1987 10. Goss AN. Bosanquet A: An animal model for temporomandibular arthrosconv. J Oral Maxiilofac Sure. 47% 1989 Il. lshimaru J-l, Gois AN: A model for osteo&throsls of the temnoromandibular ioint. J Oral Maxillofac Surg 50: I 19 I, 1992 12. K&ita K, Bronstein SL, Westesson P-L: Arthroscopic diagnosis of perforation and adhesion of the temporomandibular joint: Correlation with postmortem morphology. Oral Surg Oral Med Oral Path01 68: 130, 1989 13. Liedberg I, Westesson P-L: Diagnostic accuracy of upper compartment arthroscopy of the temporomandibuiar joint: Correlation with postmortem morphology. Oral Surg Oral Med Oral Pathol 62:618, 1986 14. Kondoh T. Westesson P-L: Ultrathin arthroscope for use in the lower compartment ofthe temporomandibuiarjoim. Oral Surg Oral Med Oral Path01 72: 146, 199 1 15. Kondoh T, Westesson P-L: Diagnostic accuracy of the temporomandibular joint lower compartment arthroscopy using ultrathin an arthroscope: A postmortem study. J Oral Maxillofac Surg 49~619, 1991
Diagnostic Accuracy of the Ultrathin Arthroscope for Temporomandibular Joint Osteoarthrosis: Comparison of Arthroscopic and Histologic Findings in a Sheep Model KENICHI KURITA, JUN-ICHI ISHIMARU,
DDS, PHD,* NOBUMI OGI, DDS, PtiD,t DDS,t AND YUJIRO HANDA, DDS, PHD$
The diagnostic accuracy of the ultrathin arthroscope was evaluated by examination of the superior joint space of the left temporomandibular joint in 20 sheep. At the time of induction of osteoarthrosis all joints were found to be normal. Six months later the arthroscopic examination was repeated and the results compared with the histologic examination. Similar findings were seen in 11 joints (55O), with arthroscopic overdiagnosis in two (10%) and underdiagnosis in seven (35%). Eight of 16 (50%) disc perforations were found. It was concluded that underdiagnosis occurred because the whole joint space cannot be examined atthroscopically and fibrillated tissue masks bone exposure.
systematically compared with the histologic changes. Bosanquet and Goss’ and Goss and Bosanquet” reported that sheep are a useful model for temporomandibular joint research. Ishimaru and Goss” succeeded in inducing osteoarthrosis in the sheep temporomandibular joint. In this study the superior compartment of the sheep temporomandibular joint with induced osteoarthrosis was viewed with an ultrathin arthroscope (diameter, 1.1 mm) to compare the arthroscopic and histologic findings.
Since its introduction,’ arthroscopy of the temporomandibular joint has been found useful in the diagnosis and treatment of temporomandibular joint disorders.2-6 An advantage of arthroscopy is the ability to detect early superficial changes in the osseous components that are not shown by magnetic resonance imaging or radiography.’ Quinn’ described chondromalacia, or softening of articular cartilage, using arthroscopy. However, the diagnostic accuracy of the arthroscopic findings for osteoarthrosis has not been
* Associate Professor, The Second Department of Oral and Maxillofacial Surgery, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan. f Visiting Researcher, Oral and Maxillofacial Surgery Unit, The University of Adelaide, Adelaide, Australia. $ Senior Lecturer, Department of Oral and Maxillofacial Surgery, Gifu University, Gifu, Japan. Supported by Grant-in-Aid for Scientific Research (C) from the Ministrv of Education. Science and Culture, Japan (project no. 0567 1665). Address correspondence and reprint requests to Dr Kurita: The Second Denartment of Oral and Maxillofacial Surgery, Schooi of Dentistry, Aichi-Gakuin University, 2-11 Suemori, Chikusaku, Nagoya, 464 Japan.
0 1994 American Association of Oral and Maxillofacial Surgeons FIGURE 1. Shiko MS-6 1IS arthroscope.
02792391/94/5203-0011$3.00/0
278
279
KURITA ET AL
Table 1. Arthroscopic and Histologic Stages of Osteoarthrosis Stage
‘*able 3. Sensitivity, Specificity, and Redicthfe Vah4esof Arthroscopic Magnoeis of Perforation (%)
Description
Arthroscopic Stage
1
Fibrous surface without fibrillation Fibrillation of the surface layer Bone exposure Smooth surface and even thickness of fibrous layer Uneven thickness of the surface layer Bone exposure
2 3 Histologic Stage I II III
Materials and Methods
The instruments used in this study were a Shinko FV-3000 arthroscopic system and a Shinko MS-6 11S arthroscope (Shinko Optical Co, Ltd, Tokyo, Japan; Fig 1). The irrigation cannula and the outer sheath for the optical fibers of the arthroscope were 1.1 mm and .8 mm in diameter, respectively. The arthroscope had a 70” field of view in air. A IO-mL syringe containing normal saline solution was attached to the irrigation cannula. The image of the joint space was observed during the procedure using a color TV camera and monitor. Arthroscopic photographs were taken with a 35 mm SLR camera (Nikon F2 [Nikon Co, Tokyo, Japan]), using Kodak SOOf1600 ASA films (Eastman Kodak Co, Rochester, NY). The animals were adult Merino sheep, weighting about 60 kg. The left temporomandibular joint of 20 sheep was examined at the commencement and termination of a series of experiments creating intraarticular osteoarthrosis.’ ’ General anesthesia was induced with an injection of thiopentone sodium into the external jugular vein and maintained with isoflurane/ N20/02 through an orotracheal tube. The preauricular region was shaved and surgically draped. A preauricular skin incision was made to expose the lateral capsule of the temporomandibular joint. The arthroscope was introduced into the joint space through a small stab incision made with a no. 11 scalpel in the central part of the capsule. Constant irrigation with normal saline was maintained through a cannula of the arthroscope to remove air bubbles and blood and to distend the superior joint space. Under this pressure, the capsule Table 2. Accuracy of Arthroscopic Diagnosis of Perforation (n = 20) True negative False negative True positive False positive
50 100 100 33
Sensitivity Specificity Positive predictive value Negative predictive value
was sufficiently distended to allow the arthroscope to freely move in the joint space. The arthroscopic findings were recorded, following which the inferior joint space was opened and the fibrocartilage gently removed from the condyle to create osteoarthrosis.” The wound was closed in layers and antibiotics were administrated intramuscularly. At 6 months afier the initial operation, the sheep were reanethetized and the joint spaces were arthroscopically observed for the presence of perforation of the disc and osteoarthrotic changes on the artitular eminence and fossa. The arthroscopic findings on the bone were classified into three stages (Table 1) by one of authors (K.K). The sheep were killed by an anesthetic overdose after arthroscopic observation. The temporomandibular joints were then removed en bloc and fixed with formalin. The specimens were decalcified and sagittally sectioned from lateral to medial for histologic study. The histologic lindings were classified into three stages (Table 1) by one of authors (N.O.). The most advanced arthroscopic and histologic stages in each joint were compared. Results
Disc perforation was observed arthroscopically in eight joints. Histologic examination confirmed disc perforation in these eight joints, and in the lateral one third of eight additional joints. Thus, eight of 16 perforations were diagnosed arthroscopically, with a 50% sensitivity and 100% positive predictive value (Tables 2, 3). The correlation between the arthroscopic and histologic diagnosis with respect to osteoarthrotic changes on the temporal bone is presented in Table 4. Of the Table 4. Correlation Between ArthroscOpic and Histologic Diagnosis Histologic Diagnosis (Stage)
Arthroscopic Diagnosis
(Stage) 1 2 3 Total
I
II
III
Tot.4
1 1 1 3
2 I 0 9
0 5 3 8
3 13 4 20
280
FIGURE 2.
ULTRA ARTHROSCOPY
FOR OSTEOARTHROSIS
Arthroscopic stage 2 and histologic stage II joint. A, Fibrillation seen arthroscopically on the posterior slope of the eminence E, eminence; D, disc.
(whife arrow heads). B, The fibrous layer on the posterior slope of the eminence is uneven (bkzck arrows). c, condyle;
20 joints, 11 (55%) were diagnosed correctly on arthroscopic examination. Seven joints (35%) were arthroscopically underdiagnosed, and two joints ( 10%) were overdiagnosed. In the histologic stage I joint, one of three joints was accurately diagnosed with the arthroscope, whereas the other two joints were overdiagnosed. In the histologic stage II joints, seven of nine joints (78%) were diagnosed accurately, with underdiagnosis of two joints (22%); there was no overdiagnosis (Fig 2). In histologic stage III joints, only three of the eight joints (38%) were correctly diagnosed arthroscopically (Fig 3). The remaining five joints were all diagnosed as an arthroscopic stage 2 in which the bone exposure was obscured by the covering fibrillation. Discussion Recently Quinn’ reported arthroscopic and histologic evidence of chondromalacia in the temporomandibular joint. However, correlation between the arthroscopic and histologic findings was not made. This
FIGURE 3. (large arrows).
is because of the technical difficulties in removing osseous tissue as a block by arthroscopy and in identifying an arthroscopically viewed site with the histologic site, as well as important ethical issues in clinical research. Thus, in this study the arthroscopic and histopathologic findings were compared using experimentally induced osteoarthrosis in a sheep joint. Osteoarthrosis was commonly underdiagnosed arthroscopically in this study; only three of eight histologic stage III joints were correctly diagnosed. The remaining five joints were underdiagnosed as arthroscopic stage 2 because of massive fibrillation covering the bone exposure (Fig 4). In this experiment a probe was not used to avoid making scratch marks on the bony surface that would be difficult to distinguish from ostoarthrosis on histologic examination. If a probe had been used for palpation of the bony surfaces, the diagnostic accuracy in histologic stage III joints might have been higher. Therefore, when much fibrillation is seen arthroscopically in clinical cases, palpation of the bony surface under the fibrillation is recommended. Eight of 16 perforations diagnosed arthroscopically
Arthroscopic stage 3 and histologic stage III joint. A, Bone exposure seen arthroscopically on the posterior slope of the eminence B, Bone exposure on the posterior slope (smaN arrows). c, condyle; E, eminence; D, disc.
KURITA ET AL
FIGURE 4. Disagreement between arthroscopic and histologic diagnosis. A, Arthroscopicaily this joint was diagnosed stage 2 because of massive fibrillation (white arrow@, whereas in B, histologically, it was diagnosed as stage Ill because of bone exposure (hluck arron:v).
were all confirmed histologically. The eight perforations that were not seen arthroscopically were all located in the lateral one third of the joint space. This result, which supports previous reports,‘2*‘3 indicates that the whole joint space cannot be observed by a single arthroscopic approach. Therefore, an additional puncture from a different direction, such as an endaural approach, or an arthroscope with a different angle of view, is necessary to inspect the entire joint space. Compared with the previous reports using human cadavers,12.13 the sensitivity for recognition of temporomandibular joint disc perforation is high. This is partly because the upper space could be seen from anterior to posterior in all joints after the capsule was exposed because the joint space is flatter in sheep than in the human. The other reason was that arthroscopic examination was performed under general anesthesia on a live animal rather than on a cadaver, which is unyielding. It was possible in this experiment to insert the ultrathin 1.1-mm diameter arthroscope and examine the joint space in all cases. Because the size of the sheep temporomandibular joint is similar to that in humans, this scope also can be used for examination of human joint. The instrument has been used recently for arthroscopy of the lower compartment of human temporomandibular joints. I4515 Arthroscopic examination with the ultrathin scope is possible under local anethesia because of the minimal surgical intervention needed. It was concluded that the diagnostic accuracy for osteoarthrosis (55%) with an ultrathin arthroscope is clinically acceptable. Acknowledgment The authors thanks Professor Aiastair N. Goss, Oral and Maxillofacial Surgery Unit. the University of Adelaide, Australia. for research support.
References I. Ohnishi M: Arthroscopy of the temporomandibular joint. J Stomatol Sot Jpn 42:207, 1975 2. Murakami K, lto K: Arthroscopy of the temporomandibuiar joint. Arthroscopic anatomy and arthroscopic approaches in the human cadaver (in Japanese). Arthroscopy 6:1, 1981 3. Goss AN, Bosanquet AG: Temporomandibular joint arthroscopy. J Oral Maxiiiofac Surg 44:6 14, 1986 4. Sanders B: Arthroscopic surgery of the temporomandibuiar joint: Treatment of internal derangement with persistent closed lock. Oral Surg Oral Med Oral Pathol 62:361, 1986 5. Moses JJ, Sartoris D, Glass R, et al: The effect of arthroscopic surgical lysis and iavage of the superior joint space on TMJ disc position and mobility. J Oral Maxillofac Surg 47:674, 1989 6. Mongomery M, Sickels JEV, Harms S. et al: Arthroscopic TMJ surgery: Etfects on signs, symptoms, and disk position. J Oral Maxiliofac Surg 47: 1263, 1989 7. Israel HA, Ratciiffe A: Early diagnosis of osteoarthrosis of temporomandibuiar joint: Correlation between arthroscopic diagnosis and keratan sulfate levels in the synoviai fluid. J Oral Maxiliofac Surg 49:708. 1991 8. Quinn JH: Arthroscopic and histologic evidence of chondromalacia in the temporomandibuiar joint. Oral Surg Oral Med Oral Path01 70:387, 1990 9. Bosanquet A, Goss AN: The sheep as a model for temporomandibular joint surgery. lnt J Oral Maxiiiofac Surg 16:600, 1987 10. Goss AN. Bosanquet A: An animal model for temporomandibular arthrosconv. J Oral Maxiilofac Sure. 47% 1989 Il. lshimaru J-l, Gois AN: A model for osteo&throsls of the temnoromandibular ioint. J Oral Maxillofac Surg 50: I 19 I, 1992 12. K&ita K, Bronstein SL, Westesson P-L: Arthroscopic diagnosis of perforation and adhesion of the temporomandibular joint: Correlation with postmortem morphology. Oral Surg Oral Med Oral Path01 68: 130, 1989 13. Liedberg I, Westesson P-L: Diagnostic accuracy of upper compartment arthroscopy of the temporomandibuiar joint: Correlation with postmortem morphology. Oral Surg Oral Med Oral Pathol 62:618, 1986 14. Kondoh T. Westesson P-L: Ultrathin arthroscope for use in the lower compartment ofthe temporomandibuiarjoim. Oral Surg Oral Med Oral Path01 72: 146, 199 1 15. Kondoh T, Westesson P-L: Diagnostic accuracy of the temporomandibular joint lower compartment arthroscopy using ultrathin an arthroscope: A postmortem study. J Oral Maxillofac Surg 49~619, 1991