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Single-channel thin-fiber and Nd: YAG laser temporomandibular joint arthroscope: development and preliminary clinical findings
Copyright 9 Munksgaard 1997
Int. Z Oral Maxillofac. Surg. 1997; 26:414 418 Printed in Denmark. All rights reserved
lntemationa]Journalof
Oral& MaxillofaciaISurgery ISSN 0901-5027
Kenichi Kurita ~, Nobumi OgP, Masahiko Toyama 2, Izumi MakP, Masao Ike ~
Single-channel thin-fiber and Nd:YAG lasertemporomandibular joint arthroscope: development and preliminary clinical findings
1Second Department of Oral and Maxillofacial Surgery, 2Department of Oral and Maxillofacial Radiology, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan
K. Kurita, N. OgL M. Toyama, L MakL M. Ike: Single-channel thin-fiber and Nd." YA G laser temporomandibular joint arthroscope: development and preliminary clinical findings. Int. J. Oral Maxillofac. Surg. 1997; 26:414 418. 9 Munksgaard, 1997 Abstract. This study evaluated the development and preliminary results of a single-channel thin-fiber and Nd:YAG laser temporomandibular joint arthroscope. No articular damage from the arthroscopic procedure and laser lysis was observed in any of the joints when the arthrotomy was performed. All three disk perforat!ons found by the arthroscope were confirmed at the time of the arthrotomy, and in these joints the tip of the arthroscope could be advanced into the inferior joint. The nine joints, where only arthroscopic laser lysis was performed, were followed up and the results were satisfactory.
Arthroscopy of the temporomandibular joint (TMJ), since it was first described in 197516, has been found to be useful in both diagnosis and treatment of TMJ disorders 4,9,11,13-15. BJORNLAND et al. 2, in an animal study using goats, reported degenerative changes within the TMJ after diagnostic arthroscopy. Although goats are used extensively in orthopedic research because of their tendency toward spontaneous osteoarthrosis, BJORNLAND'Sstudy does indicate the need to minimize iatrogenic articular damage. Thus, both the number and size of punctures need to be limited. Lens-type arthroscopes are fragile and this limits the minimum diameter to 2.3 mm. Compared with conventional lens-type arthroscopes, fiber optic arthroscopes can be made much thinner, however, the quality of the image is less satisfactory. Commercially
available thin-fiber arthroscopes have 4200 fibers2~ We have investigated the diagnostic accuracy of such a scope using an osteoarthrotic sheep model 7 and found a diagnostic accuracy of 500/01~. It was also found that the dark circles around the optic fibers interfered
Key words: temporomandibular joint; arthroscopy; laser. Accepted for publication 3 April 1997
with the image, and the view was, therefore, dark with a lack of depth. Multiple puncture sites are required to introduce surgical instruments for therapeutic activity under direct arthroscopic vision. OHNISHI ls developed an arthroscope with two channels, thus
Table 1. Classification of TMJ dysfunction and results of laser lysis on nine joints (degree of disturbance is based on worst degree of max. mouth opening or max. value of visual analog scales) Max. value of visual analog Degree of TMJ Max. mouth scalesa (No. of joints n=9) disorders opening (ram) (0-100) Preoperation Postoperation nil slight moderate severe
40+ 35-39 30-34 0-29
0 1-33 34-66 67-100
0 0 2 7
7 2 0 0
a Visual analog scales consist of pain at rest, pain with mandibular motion, pain on chewing, and interference with daily life.
T M J arthroscope Inner C h a n n e l for Treatment( r 0.4 m m ) Light G u i d e Fibers Lens and I m a g e Fibers
I
~/ k . l d l l l l l l
Fig. 1. Cross section of thin-solid-fiber arthroscope showing internal arrangement.
allowing t r e a t m e n t u n d e r direct vision. T h e external diameter o f this instrum e n t was 3.8 m m which, a l t h o u g h small, is large in c o m p a r i s o n to the size o f the T M J . M o r e recently, lasers have been developed for i n t r a - a r t i c u l a r surgery, a n d these are m u c h t h i n n e r t h a n conventional surgical instruments. I n this study, the d e v e l o p m e n t a n d p r e l i m i n a r y clinical findings of a singlec h a n n e l thin-fiber a n d N d : Y A G laser T M J a r t h r o s c o p e are reported.
Material and methods A prototype thin-fiber arthroscope with a central channel for a laser was developed in collaboration with a Japanese company (M& M Co., Tokyo, Japan). It has the following specifications: an external stainless steel endoscopic cannula, 2 mm in external dianaeter; an arthroscope with an external diameter of 1.5 mm containing 15 000 optic fibers and with a 70~ field of view; an inner channel 0.40 mm in diameter within the arthroscope
to carry a 0.25 mm Nd:YAG laser with a power of 5 watts (Fig. 1). The length of the probe was 50 mm with a total weight of 95 g including the fiber optic and light cables (Fig. 2a, b). The light source was a 300 W halogen lamp. Irrigation during arthroscopy was maintained by fluid passing between the cannula and scope. The image of the joint space was observed through a color TV camera (FVS-3000, M& M Co., Tokyo, Japan) and monitor (PVM2044Q, Sony Co., Tokyo, Japan). Arthroscopic photographs were taken with a 35 mm SLR camera (Nikon F2, Nikon Co., Tokyo, Japan) using a 1600 ASA film (Fujichrome, Fuji Film Co., Tokyo, Japan). The arthroscopic technique is similar to conventional diagnostic arthroscopy ~2,19,25. The patient's TMJ was prepared and draped under general anesthesia. The joint space was inflated by injection of 2 ml of sterile saline into the superior joint space. A sharp trochar placed within the endoscopic cannula was used to penetrate the capsule into the posterior recess of the superior joint space. Appropriate placement was confirmed by the outflow of sterile saline on removal of the
415
sharp trochar. The scope was then inserted and irrigation maintained by inflow via the cannula and outflow via the 18-gauge needle used to inflate the joint initially. The scope was then inserted into the cannula and a full examination performed. The results were recorded on video and selected features photographed. The Nd:YAG laser was then inserted into the inner channel and the tip placed directly against the fibrous adhesions under direct vision. The laser beam was then activated until lysis was observed. It was then repositioned against the next fibrous adhesion under direct vision, reactivated, and this sequence repeated until all adhesions had been treated. This instrumentation was used on 16 TMJs in 12 patients. Of these, seven joints in five patients needed arthrotomy because laser arthroscopic treatment had not given rise to interincisal mouth opening of more than 40 ram. In these cases the results of the examination and treatment were compared with the surgical findings. The remaining nine joints in nine patients had only arthroscopic treatment. In two patients arthroscopic lysis was performed on one side of the TMJs while an arthrotomy was carried out on the other side. Follow-up examination was performed in these cases, and the results were assessed using a modification of the TMJ criteria of the American Association (AAOMS) and of the International Association of Oral and Maxillofacial Surgeons (IAOMS) 1,5.
Results In all 16 joints, the a r t h r o s c o p e was easily passed into the posterior recess of the u p p e r j o i n t space (Fig. 3), a n d the tip o f the scope was easily a d v a n c e d into the a n t e r i o r recess o f all j o i n t s (Fig. 4). I n three joints, disk p e r f o r a t i o n was o b s e r v e d a n d the tip o f the a r t h r o s c o p e could be a d v a n c e d into the inferior j o i n t space o f the three joints. T h e
Fig. 2. a) Thin-solid-fiber arthroscope showing port of inner channel (P), endoscope cannula (E), fiber optic and light cable (C), and quartz laser fiber (L). b) Magnification of tip of scope showing quartz laser fiber (L) protruding from inner channel of scope (arrow).
416
K u r i t a et aL
Fig. 3. Arthroscopic view of posterior recess of upper joint space of left joint with condyle translated forward showing synovial hypertrophy (S), eminence (E), fossa (F) and posterior attachment (PA).
arthroscopic findings correlated with the preoperative M R image (Fig. 5a, b). Laser lysis was performed in all joints, but in seven joints arthrotomy was necessary because the maximal mouth opening did not reach 40 mm by laser lysis only. When the arthrotomy was performed, no articular damage from the arthroscopic procedure was observed. There was a close correlation between the arthroscopic and arthrotomy findings regarding number of disk perforations. All three disk perforations found by the arthroscope were confirmed at the time of arthrotomy. The diameters of the disk perforations were 3, 3 and 5 mm respectively. In nine joints, arthroscopic laser lysis was performed (Fig. 6). The patients were followed up from 160 to 556 days and the results are presented in Table 1. Discussion
Fig. 4. Arthroscopic view of anterior recess of upper joint space of left joint showing anterior
recess of upper joint space (AUS), fibrous adhesion (F), and eminence (E).
This study shows that a single 2 mmdiameter channel arthroscopy can provide excellent intra-articular vision both for examination and laser lysis of fibrous adhesions. The tip of the scope is fine enough to be advanced into the anterior recess, which is the usual site of fibrous adhesions. It can also be passed through small disk perforations so that the inferior joint space can be examined. No evidence of damage by the arthroscopic procedure was observed in any of the seven joints where arthroscopy was followed by arthrotomy. The external diameter of the cannula is a key issue in TMJ arthroscopy. Lenstype arthroscopes provide an excellent view but the thinner they become the greater the risk of breakage 24. The op-
Fig. 5. a) Arthroscopic view of condyle after scope has passed through perforation. Osteophyte (O), condyle (C), disk (D), disk perforation
(arrow heads), and lower joint space (LS). b) Preoperative MRI, parasagittal plane. Osteophyte on condyle (arrows).
T M J arthroscope
Fig. 6. Arthroscopic view showing fibrous adhesion (F), quartz laser fiber (L), vaporized fibrous adhesion (arrows). The broadly based adhesion is not fully released at this stage.
tical fiber-type arthroscope can be both thin and strong. Fiber arthroscopes 2~ currently available commercially contain 4200 optic fibers. However, they lack depth of field, the demarcation between fibers can be seen, and the diagnostic accuracy in animal studies is low 1~ The first two objections have been overcome by increasing the number of fibers to 15 000. Studies comparing diagnostic accuracy to histologic staging of osteoarthrosis in sheep are currently in progress. A n o t h e r key issue is the number of entry points into the joints and the type of intra-articular surgery. Shavers and electrocoagulation have been widely used in orthopedics and have been used for T M J s 12,23,~s. These usually require additional entry points into the joints and increase the amount of potential damage. BJORNLAND et al. 2 reported degenerative changes in goats following arthroscopy, although goats do have a tendency towards spontaneous osteoarthrosis. ISmMARU & GOSS7 showed that minor intentional damage to the condylar structures results in reproducible osteoarthrotic changes in sheep, an animal with no tendency towards spontaneous osteoarthrosis. Vigorous use of arthroscopic shavers in the articular eminence of normal sheep resulted in considerable intra-articular pathology 22. Therefore, multiple entry into the joint should be avoided so as not to damage the articular surface. In this respect, the scope used in the present study has the advantage that, by reducing additional entry points, the N d : Y -
A G laser can be inserted through the inner channel of the scope. Lasers have been used to vaporize soft tissue without bleeding both generally 2t and in intra-articular T M J surgery 17. The N d : Y A G laser can be used to release fibrous adhesion across the joint space and also to smooth surface fibrillation. It is essential, however, that the laser tip is placed directly against the fibrous adhesion under direct vision, as blind vaporization may cause unwanted change 3. In this regard the H o l m i u m laser causes less deep damage 6,s, but current H o l m i u m lasers are too large to pass through the fine channel of the scope. In conclusion, this study demonstrates the potential of a single-channel fine-fiber arthroscope with an inner channel for an N d : Y A G laser in the management of intra-articular adhesions.
Acknowledgment. This study was supported by a grant from the Japanese Private University Foundation. We are extremely grateful to Professor Alastair N. Goss, Oral and Maxillofacial Surgery Unit, the University of Adelaide, Australia, for his support. References 1. AMERICAN ASSOCIATIONOF ORAL AND MAXILLOFACIALSURGEONS.Ad hoc Study Group on TMJ Meniscus Study: 1984 Criteria for TMJ meniscus surgery. 1528 November 1984. 2. BJORNLANDT, RORVIKM, HAANAESHR, et al. Degenerative changes in the temporomandibular joint after diagnostic arthroscopy. An experimental study in goats. Int J Oral Maxillofac Surg 1994: 23: 41-5. 3. BRADRICK JP, ECKI-IAUSERML, INDRESANO AT. Early response of canine temporomandibular joint tissues to arthroscopically guided neodymium: YAG laser wounds. J Oral Maxillofac Surg 1992: 50: 835-42. 4. Goss AN, BOSANQUETAG. Temporomandibular joint arthroscopy. J Oral Maxillofac Surg 1986: 44: 614-7. 5. Goss AN. Toward an international consensus on temporomandibular joint surgery. Int J Oral Maxillofac Surg 1993: 22: 78-81. 6. HENDLERBH, GATENOJ, MOOARP, et al. Holmium: YAG laser arthroscopy of the temporomandibular joint. J Oral Maxillofac Surg 1992: 50: 931-4. 7. ISHIMARUJ-I, Goss AN. A model for osteoarthritis of the temporomandibular joint. J Oral Maxillofac Surg 1992: 50: 1191-5. 8. KOSLINMG, MARTINJC. The use of the
417
holmium laser for temporomandibular joint arthroscopic surgery. J Oral Maxillofac Surg 1993: 51: 122-3. 9. KURITAK, BRONSTEIN SL, WESTESSONPL. Arthroscopic diagnosis of perforation and adhesion of the temporomandibular joint: correlation with postmortem morphology. Oral Surg 1989: 68: 130-4. 10. KURITAK, OGI N, ISHIMARUJ, et al. Diagnostic accuracy of the ultrathin arthro-
scope for temporomandibular joint osteoarthrosis: comparison of arthroscopic and histologic findings in a sheep model. J Oral Maxillofac Surg 1994: 52: 278-81. 11. LIEDBERGJ, WESTESSONP-L. Diagnostic accuracy of upper compartment arthroscopy of the temporomandibular joint: correlation with postmortem morphology. Oral Surg 1986: 62: 618-24. 12. MCCAIN JP. Arthroscopy of the hmnan temporomandibular joint. J Oral Maxillofac Surg 1988: 46: 648-55. 13. MONTGOMERY M, VAN SICKELS JE, HARMS SE, et al. Arthroscopic TMJ surgery: effects on signs, symptoms, and disc position. J Oral Maxillofac Surg 1989: 47: 1263-71. 14. MosEs JJ, SARTORISD, GLASS R, et al. The effect of arthroscopic surgical Iysis and lavage of the superior joint space on TMJ disc position and mobility. J Oral Maxillofac Surg 1989: 47: 674-8. 15. MURAKAMIK. Arthroscopic anatomy of the temporomandibular joint. Oral and Maxillofacial Surgery Clinics of North America 1889: 1:55 63. 16. OrI~sni M. Arthroscopy of the temporomandibular joint. J Stomatol Soc Jpn 1975: 42:207-13 [in Japanese]. 17. OHNISHI M. Arthroscopic laser surgery and suturing for temporomandibular joint disorders: technique and clinical results. Arthroscopy 1991: 7: 212-20. 18. OHNISHIM. Newly designed needle scope system for the arthroscopic surgery by double-channel sheath method. J Jpn Soc TMJ 1989: 1:209-16 [in Japanese]. 19. SANDERSB. Arthroscopic surgery of the temporomandibular joint: treatment of internal derangement with persistent closed lock. Oral Surg 1986: 62:361 72. 20. SAWAI K, ISHIBASHIK, ASADA K, et al.
Development and application of fine needle fiber-arthroscope to the TMJ. Diagnostic use of the system. Jpn J Oral Maxillofac Surg t990: 36:423-33 [in Japanese]. 21. SCHURRMO, V~EI-IRMANNM, KUNERTW, et al. Histologic effects of different technologies for dissection in endoscopic surgery: Nd:YAG laser, high frequency and water-jet. Endosc-Surg-Allied-Technol 1994: 2: 195-201. 22. SEGAMIN. Arthroscopic abrasion arthroscopy in sheep TMJ. AAOMS (oral abstract session 14), 1993: 159-60. 23. SEGAMIN, MURAKAMIK, MIYAKI K, et al. Operative arthroscopy using electric
418
Kurita et al.
cautery, LASER, and shaver for patients with internal derangement of the temporomandibular joint. Jpn J Oral Maxillofac Surg 1990: 36:2094-102 [in Japanese]. 24. SmAMI N, N~smMuga T, CI~N W-H, et al. The development and clinical appli-
cation of simple diagnostic arthroscopy of the temporomandibular joint. Jpn J Oral Maxillofac Surg 1992: 38:93640 [in Japanese]. 25. TARRO AW. Arthroscopic diagnosis and surgery of the temporomandibular joint. J Oral Maxillofac Surg 1988: 46: 282-9.
Address: Associate Professor Keniehi Kurita The Second Department of Oral and Maxillofacial Surgery School of Dentistry, Aichi-Gakuin University Suemori, Chikusaku Nagoya 464, Japan
Int. Z Oral Maxillofac. Surg. 1997; 26:414 418 Printed in Denmark. All rights reserved
lntemationa]Journalof
Oral& MaxillofaciaISurgery ISSN 0901-5027
Kenichi Kurita ~, Nobumi OgP, Masahiko Toyama 2, Izumi MakP, Masao Ike ~
Single-channel thin-fiber and Nd:YAG lasertemporomandibular joint arthroscope: development and preliminary clinical findings
1Second Department of Oral and Maxillofacial Surgery, 2Department of Oral and Maxillofacial Radiology, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan
K. Kurita, N. OgL M. Toyama, L MakL M. Ike: Single-channel thin-fiber and Nd." YA G laser temporomandibular joint arthroscope: development and preliminary clinical findings. Int. J. Oral Maxillofac. Surg. 1997; 26:414 418. 9 Munksgaard, 1997 Abstract. This study evaluated the development and preliminary results of a single-channel thin-fiber and Nd:YAG laser temporomandibular joint arthroscope. No articular damage from the arthroscopic procedure and laser lysis was observed in any of the joints when the arthrotomy was performed. All three disk perforat!ons found by the arthroscope were confirmed at the time of the arthrotomy, and in these joints the tip of the arthroscope could be advanced into the inferior joint. The nine joints, where only arthroscopic laser lysis was performed, were followed up and the results were satisfactory.
Arthroscopy of the temporomandibular joint (TMJ), since it was first described in 197516, has been found to be useful in both diagnosis and treatment of TMJ disorders 4,9,11,13-15. BJORNLAND et al. 2, in an animal study using goats, reported degenerative changes within the TMJ after diagnostic arthroscopy. Although goats are used extensively in orthopedic research because of their tendency toward spontaneous osteoarthrosis, BJORNLAND'Sstudy does indicate the need to minimize iatrogenic articular damage. Thus, both the number and size of punctures need to be limited. Lens-type arthroscopes are fragile and this limits the minimum diameter to 2.3 mm. Compared with conventional lens-type arthroscopes, fiber optic arthroscopes can be made much thinner, however, the quality of the image is less satisfactory. Commercially
available thin-fiber arthroscopes have 4200 fibers2~ We have investigated the diagnostic accuracy of such a scope using an osteoarthrotic sheep model 7 and found a diagnostic accuracy of 500/01~. It was also found that the dark circles around the optic fibers interfered
Key words: temporomandibular joint; arthroscopy; laser. Accepted for publication 3 April 1997
with the image, and the view was, therefore, dark with a lack of depth. Multiple puncture sites are required to introduce surgical instruments for therapeutic activity under direct arthroscopic vision. OHNISHI ls developed an arthroscope with two channels, thus
Table 1. Classification of TMJ dysfunction and results of laser lysis on nine joints (degree of disturbance is based on worst degree of max. mouth opening or max. value of visual analog scales) Max. value of visual analog Degree of TMJ Max. mouth scalesa (No. of joints n=9) disorders opening (ram) (0-100) Preoperation Postoperation nil slight moderate severe
40+ 35-39 30-34 0-29
0 1-33 34-66 67-100
0 0 2 7
7 2 0 0
a Visual analog scales consist of pain at rest, pain with mandibular motion, pain on chewing, and interference with daily life.
T M J arthroscope Inner C h a n n e l for Treatment( r 0.4 m m ) Light G u i d e Fibers Lens and I m a g e Fibers
I
~/ k . l d l l l l l l
Fig. 1. Cross section of thin-solid-fiber arthroscope showing internal arrangement.
allowing t r e a t m e n t u n d e r direct vision. T h e external diameter o f this instrum e n t was 3.8 m m which, a l t h o u g h small, is large in c o m p a r i s o n to the size o f the T M J . M o r e recently, lasers have been developed for i n t r a - a r t i c u l a r surgery, a n d these are m u c h t h i n n e r t h a n conventional surgical instruments. I n this study, the d e v e l o p m e n t a n d p r e l i m i n a r y clinical findings of a singlec h a n n e l thin-fiber a n d N d : Y A G laser T M J a r t h r o s c o p e are reported.
Material and methods A prototype thin-fiber arthroscope with a central channel for a laser was developed in collaboration with a Japanese company (M& M Co., Tokyo, Japan). It has the following specifications: an external stainless steel endoscopic cannula, 2 mm in external dianaeter; an arthroscope with an external diameter of 1.5 mm containing 15 000 optic fibers and with a 70~ field of view; an inner channel 0.40 mm in diameter within the arthroscope
to carry a 0.25 mm Nd:YAG laser with a power of 5 watts (Fig. 1). The length of the probe was 50 mm with a total weight of 95 g including the fiber optic and light cables (Fig. 2a, b). The light source was a 300 W halogen lamp. Irrigation during arthroscopy was maintained by fluid passing between the cannula and scope. The image of the joint space was observed through a color TV camera (FVS-3000, M& M Co., Tokyo, Japan) and monitor (PVM2044Q, Sony Co., Tokyo, Japan). Arthroscopic photographs were taken with a 35 mm SLR camera (Nikon F2, Nikon Co., Tokyo, Japan) using a 1600 ASA film (Fujichrome, Fuji Film Co., Tokyo, Japan). The arthroscopic technique is similar to conventional diagnostic arthroscopy ~2,19,25. The patient's TMJ was prepared and draped under general anesthesia. The joint space was inflated by injection of 2 ml of sterile saline into the superior joint space. A sharp trochar placed within the endoscopic cannula was used to penetrate the capsule into the posterior recess of the superior joint space. Appropriate placement was confirmed by the outflow of sterile saline on removal of the
415
sharp trochar. The scope was then inserted and irrigation maintained by inflow via the cannula and outflow via the 18-gauge needle used to inflate the joint initially. The scope was then inserted into the cannula and a full examination performed. The results were recorded on video and selected features photographed. The Nd:YAG laser was then inserted into the inner channel and the tip placed directly against the fibrous adhesions under direct vision. The laser beam was then activated until lysis was observed. It was then repositioned against the next fibrous adhesion under direct vision, reactivated, and this sequence repeated until all adhesions had been treated. This instrumentation was used on 16 TMJs in 12 patients. Of these, seven joints in five patients needed arthrotomy because laser arthroscopic treatment had not given rise to interincisal mouth opening of more than 40 ram. In these cases the results of the examination and treatment were compared with the surgical findings. The remaining nine joints in nine patients had only arthroscopic treatment. In two patients arthroscopic lysis was performed on one side of the TMJs while an arthrotomy was carried out on the other side. Follow-up examination was performed in these cases, and the results were assessed using a modification of the TMJ criteria of the American Association (AAOMS) and of the International Association of Oral and Maxillofacial Surgeons (IAOMS) 1,5.
Results In all 16 joints, the a r t h r o s c o p e was easily passed into the posterior recess of the u p p e r j o i n t space (Fig. 3), a n d the tip o f the scope was easily a d v a n c e d into the a n t e r i o r recess o f all j o i n t s (Fig. 4). I n three joints, disk p e r f o r a t i o n was o b s e r v e d a n d the tip o f the a r t h r o s c o p e could be a d v a n c e d into the inferior j o i n t space o f the three joints. T h e
Fig. 2. a) Thin-solid-fiber arthroscope showing port of inner channel (P), endoscope cannula (E), fiber optic and light cable (C), and quartz laser fiber (L). b) Magnification of tip of scope showing quartz laser fiber (L) protruding from inner channel of scope (arrow).
416
K u r i t a et aL
Fig. 3. Arthroscopic view of posterior recess of upper joint space of left joint with condyle translated forward showing synovial hypertrophy (S), eminence (E), fossa (F) and posterior attachment (PA).
arthroscopic findings correlated with the preoperative M R image (Fig. 5a, b). Laser lysis was performed in all joints, but in seven joints arthrotomy was necessary because the maximal mouth opening did not reach 40 mm by laser lysis only. When the arthrotomy was performed, no articular damage from the arthroscopic procedure was observed. There was a close correlation between the arthroscopic and arthrotomy findings regarding number of disk perforations. All three disk perforations found by the arthroscope were confirmed at the time of arthrotomy. The diameters of the disk perforations were 3, 3 and 5 mm respectively. In nine joints, arthroscopic laser lysis was performed (Fig. 6). The patients were followed up from 160 to 556 days and the results are presented in Table 1. Discussion
Fig. 4. Arthroscopic view of anterior recess of upper joint space of left joint showing anterior
recess of upper joint space (AUS), fibrous adhesion (F), and eminence (E).
This study shows that a single 2 mmdiameter channel arthroscopy can provide excellent intra-articular vision both for examination and laser lysis of fibrous adhesions. The tip of the scope is fine enough to be advanced into the anterior recess, which is the usual site of fibrous adhesions. It can also be passed through small disk perforations so that the inferior joint space can be examined. No evidence of damage by the arthroscopic procedure was observed in any of the seven joints where arthroscopy was followed by arthrotomy. The external diameter of the cannula is a key issue in TMJ arthroscopy. Lenstype arthroscopes provide an excellent view but the thinner they become the greater the risk of breakage 24. The op-
Fig. 5. a) Arthroscopic view of condyle after scope has passed through perforation. Osteophyte (O), condyle (C), disk (D), disk perforation
(arrow heads), and lower joint space (LS). b) Preoperative MRI, parasagittal plane. Osteophyte on condyle (arrows).
T M J arthroscope
Fig. 6. Arthroscopic view showing fibrous adhesion (F), quartz laser fiber (L), vaporized fibrous adhesion (arrows). The broadly based adhesion is not fully released at this stage.
tical fiber-type arthroscope can be both thin and strong. Fiber arthroscopes 2~ currently available commercially contain 4200 optic fibers. However, they lack depth of field, the demarcation between fibers can be seen, and the diagnostic accuracy in animal studies is low 1~ The first two objections have been overcome by increasing the number of fibers to 15 000. Studies comparing diagnostic accuracy to histologic staging of osteoarthrosis in sheep are currently in progress. A n o t h e r key issue is the number of entry points into the joints and the type of intra-articular surgery. Shavers and electrocoagulation have been widely used in orthopedics and have been used for T M J s 12,23,~s. These usually require additional entry points into the joints and increase the amount of potential damage. BJORNLAND et al. 2 reported degenerative changes in goats following arthroscopy, although goats do have a tendency towards spontaneous osteoarthrosis. ISmMARU & GOSS7 showed that minor intentional damage to the condylar structures results in reproducible osteoarthrotic changes in sheep, an animal with no tendency towards spontaneous osteoarthrosis. Vigorous use of arthroscopic shavers in the articular eminence of normal sheep resulted in considerable intra-articular pathology 22. Therefore, multiple entry into the joint should be avoided so as not to damage the articular surface. In this respect, the scope used in the present study has the advantage that, by reducing additional entry points, the N d : Y -
A G laser can be inserted through the inner channel of the scope. Lasers have been used to vaporize soft tissue without bleeding both generally 2t and in intra-articular T M J surgery 17. The N d : Y A G laser can be used to release fibrous adhesion across the joint space and also to smooth surface fibrillation. It is essential, however, that the laser tip is placed directly against the fibrous adhesion under direct vision, as blind vaporization may cause unwanted change 3. In this regard the H o l m i u m laser causes less deep damage 6,s, but current H o l m i u m lasers are too large to pass through the fine channel of the scope. In conclusion, this study demonstrates the potential of a single-channel fine-fiber arthroscope with an inner channel for an N d : Y A G laser in the management of intra-articular adhesions.
Acknowledgment. This study was supported by a grant from the Japanese Private University Foundation. We are extremely grateful to Professor Alastair N. Goss, Oral and Maxillofacial Surgery Unit, the University of Adelaide, Australia, for his support. References 1. AMERICAN ASSOCIATIONOF ORAL AND MAXILLOFACIALSURGEONS.Ad hoc Study Group on TMJ Meniscus Study: 1984 Criteria for TMJ meniscus surgery. 1528 November 1984. 2. BJORNLANDT, RORVIKM, HAANAESHR, et al. Degenerative changes in the temporomandibular joint after diagnostic arthroscopy. An experimental study in goats. Int J Oral Maxillofac Surg 1994: 23: 41-5. 3. BRADRICK JP, ECKI-IAUSERML, INDRESANO AT. Early response of canine temporomandibular joint tissues to arthroscopically guided neodymium: YAG laser wounds. J Oral Maxillofac Surg 1992: 50: 835-42. 4. Goss AN, BOSANQUETAG. Temporomandibular joint arthroscopy. J Oral Maxillofac Surg 1986: 44: 614-7. 5. Goss AN. Toward an international consensus on temporomandibular joint surgery. Int J Oral Maxillofac Surg 1993: 22: 78-81. 6. HENDLERBH, GATENOJ, MOOARP, et al. Holmium: YAG laser arthroscopy of the temporomandibular joint. J Oral Maxillofac Surg 1992: 50: 931-4. 7. ISHIMARUJ-I, Goss AN. A model for osteoarthritis of the temporomandibular joint. J Oral Maxillofac Surg 1992: 50: 1191-5. 8. KOSLINMG, MARTINJC. The use of the
417
holmium laser for temporomandibular joint arthroscopic surgery. J Oral Maxillofac Surg 1993: 51: 122-3. 9. KURITAK, BRONSTEIN SL, WESTESSONPL. Arthroscopic diagnosis of perforation and adhesion of the temporomandibular joint: correlation with postmortem morphology. Oral Surg 1989: 68: 130-4. 10. KURITAK, OGI N, ISHIMARUJ, et al. Diagnostic accuracy of the ultrathin arthro-
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Address: Associate Professor Keniehi Kurita The Second Department of Oral and Maxillofacial Surgery School of Dentistry, Aichi-Gakuin University Suemori, Chikusaku Nagoya 464, Japan