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Arthroscopy of the rabbit temporomandibular joint
lilt. J. Oral Maxillofac. Surg, 1986: 15: 170-175 (Key words: arthroscopy; joint. temporomandibular; surgery, oral and maxillofacial)
Arthroscopy of the rabbit temporomandibular joint ANDERS HOLMLUND, GUSTAF HELLSING AND GISLE BANG Departments of Oral Surgery and Stomathognatic Physiology, Karolinska Institutet, Huddinge, Sweden and Department of Oral Pathology and Forensic Odontology. Faculty of Dentistry. University of Bergen. Haukeland Hospital. Bergen. Norway
ABSTRACT - Arthroscopy of the rabbit temporomandibular joint was evaluated experimentally on 22 rabbits. A small arthroscope with socalled "Selfoc"-system was employed. The reaction to arthroscopy was analyzed clinically. Macroscopic dissection and histology were then employed to detect possible pathological changes in the joints at periodic intervals. The established criteria for evaluation of postoperative reactions were erythema, suppuration, weight changes and chewing capacity. The results of this study indicate that the rabbit temporomandibular joint may be arthroscoped with subsequent minor reversible changes. It also seems feasible to assume that temporomandibular joint arthroscopy in humans runs a low risk for postoperative complications.
(Accepted for publication 1 December 1984)
Arthroscopy has gained general acceptance as an important and non-injurious aid in knee joint diagnostics'-". Small arthroscopes, so-called needle scopes, permitting access to small joints, are now available. The temporomandibular joint (TMJ) is diffieult to examine clinically and radiographically. The advantage of a diagnostic method allowing inspection and biopsy of internal joint 'structures is thus obvious. In an autopsy study, HOLMLUND & HELLSING S demonstrated a high degree of diagnostic accuracy regarding TMJ arthroscopy. OHNISHI 8,9 and HELLSING et al. 3 ,4 have reported the successful performance of
arthroscopy on humans; however, no systematic evaluation of TMJ arthroscopy has been performed as yet. A histological study of the rabbit TMJ6 indicated good restitution 8 weeks after arthroscopy. In the current study involving rabbits, histology and dissection were employed in order to evaluate the probability of arthroscopic postoperative complications.
Material and methods A total of22 "New Zealand white" rabbits (local breeder, Axell, Eked), Sweden) of both sexes and
ARTHROSCOPY OF RABBIT JOINT Table I. Group distribution and observation time Rabbit Observano. tion time 5 days 1,3 group I dissection 2,4 histology 28 days group II dissection 5,7,9 histology 6,8,10 all more than 3 Y, months old were utilized in the study. 10 of these rabbits were used in a pilot study, their joints being dissected and anatomically investigated. 2 other rabbits were used on 4 occasions in order to establish a reliable anaesthetic procedure and arthroscopic technique. The 10 remaining rabbits were employed in the experiments described below. Table I illustrates the group distribution. Arthroscopy was performed on one side, with the contralateral joint as control. After postoperative observation periods of 5 days (group I) and 28 days (group II), the animals were sacrificed. Macroscopic dissection was performed on every second rabbit (Table 1). If changes appeared to be pathological, the specimen underwent histological examination. The joints of rabbits 2, 4, 6, 8 and 10were examined only histologically (Table I). All rabbits were maintained on a standard diet of pellets and water ad libitum. The experimental rabbits were individually housed in a c1imatecontrolled animal facility (50% RH, dark/light schedule 12/12). Arthroscopy A needlescope with the "Selfoc"-system (Olympus Optical Co, Tokyo) was used. It consisted of
Fig. 1. The needlescope used in the present study.
171
2 trocars, a cannula and telescope with connected fibre optic cable (Fig. I). The telescope had a diameter of 1.7 mrn, surrounded by the cannula, diameter 2.0 mm). The viewing lens had an optical inclination of 16°. The arthroscope was connected to a light source with enclosed electronic flash (Karl Storz GmbH Co, D-7200 Tuttlingen). Glutaraldehyde solution (2%) was used for sterilization. The rabbits were anaesthetized by intramuscular injection of a neurolept analgesic combination of fentanyl-fluanizone with diazepam. In all rabbits the lower joint compartment was investigated. The upper compartment of rabbit I was also examined. Hair overlying the TMJ was shaved with an electric razor and the skin scrubbed with antiseptic soap. The TMJ and a suitable puncture point were localized by palpation. A small needle was then inserted and advanced toward the condyle in antero-inferior direction until resistance was detected. The lower joint compartment was distended by
Fig Za. Arthroscopic view of the postero-lateral
portion of the right condyle of rabbit 3; posterior portion of the disk upper most. Arrow indicates a small piece of torn off cartilage.
Fig. lb. The same condyle during dissection with clearly visible scratches.
172
HOLMLUND, HELLSING AND BANG
Fig. 3. The right condyle of rabbit 9 during dissection. A small but distinct furrow is seen on the lateral portion of the condyle (arrow).
injection of an isotonic saline solution. A small incision was made through the skin and the subcutaneous tissue lateral to the joint capsule identified. The capsule of the lower compartment was then punctured by the sharp trocar. The latter was subsequently exchanged for a blunt trocar and the cannula further introduced into the joint cavity. The trocar was finally replaced by the telescope and the joint examined. Consistent distention and a clear view was achieved by irrigation of the joint cavity with an isotonic saline solution. Scratches were deliberately made on the condylar cartilage in rabbit 3, group I, and rabbit 9, group II, using the sharp trocar, Figs. 2a,b and 3. Arthroscopic photographs were obtained using an SLR camera (Nikkon F3 Nippon Koga Ku K.K ., Tokyo Japan) with a special endoscopy lens (Karl Storz GmbH Co) and Ektachrome 400 ASA daylight films. The wound was closed with I or 2 no. 4-0 polyglycolic acid sutures. No antibiotics or other drugs were administered postoperatively. After recovery from anaesthesia the rabbits were immediately returned to their cages. The response to arthroscopy was evaluated according to 4 criteria: erythema, suppuration, weight changes and chewing capacity. Erythema and suppuration were judged to be either present or absent and were evaluated on days 1,2, 5, 7, 14, 21 and 28. Weight was registered preoperatively and after 5 days in group 1. In group II, weight was registered preoperatively and at I, 2, 3 and 4 weeks. A piece of wood was used postoperatively to test chewing capacity. Pellets and water consumption and gnawing behaviour were employed as measures of normal chewing capacity. The animals in groups I and II were
sacrified after 5 and 28 days, respectively, by means of an intravenous overdose of barbiturate. The TMJ's were immediately removed en bloc with preserved joint capsules. Both joints of rabbits I, 3, 5, 7 and 9 were dissected and each pair compared macroscopically. Photographic documentation was obtained with a Nikkon Medicam camera and Ektachrome 64 ASA daylight film. On rabbits 2, 4, 6, 8 and 10, the TMJ preparation was placed in 5% neutral buffered formalin. Approximately 2 mm thick sagittal sections from the midline were cut by means of a rotating sawtoothed disk under water cooling. The specimens were demineralized in 4N formic acid, dehydrated, embedded in paraffin, cut at 3-4 p and stained with hematoxylin, eosin and saffranin. The sections were evaluated blind, i.e., without prior knowledge of the experimental protocol.
Results In the pilot study, joint position was found to be more superficial than in humans. Except for smaller dimension, the gross anatomy and structural appearance were similar to corresponding features of the human TMJ. Left and right joints of each rabbit displayed a symmetric appearance, and there were only small inter-individual variations in the anatomy.
Fig. 4a. Rabbit 2, right joint. Arthroscopic view of the central part ' of the lower compartment. Disk upper most. To the left (arrow) a small tornoff piece of the condylar cartilage.
ARTHROSCOPY OF RABBIT JOINT
Fig. 4b. A more anterior view of the same joint compartment.
Arthroscopic observations
The condylar and inferior disk surfaces and the posterior disk attachment were investigated in all cases. Additionally, in rabbit 1 the upper compartment was also examined. The richly vascularized synovial tissue differed radically from the glistening but pale and avascular surfaces of the condyle, disk and fossa. Figs. 4a, b show typical arthroscopic views.
173
Fig. 5. Rabbit 5, right condyle during dissection. A small furrow in the supero-Iateral portion of the condyle (arrow).
No sign of suppuration was found in any of the cases examined . Table 2 illustrates weight changes. 2 of the animals, sacrificed after 5 days, group I, exhibited slight weight loss. In group II, 2 rabbits experienced a slight weight reduction by day 7. After 2 and 4 weeks, all the rabbits in group II had normal weight, (X = +460 g, range 260-620 g). Daily observations indicated no impairment in the ability to eat pellets or drink water. All gnawed on the pieces of wood offered postoperatively and seemed to maintain good general health.
Clinical observations
Postoperative erythema at the site of incision was observed on rabbit 3 for 2 days.
+110
No pathological changes were observed in the temporal fossa or disk. In rabbit 5 (right joint), a small but distinct furrow with intact cartilage was observed in the supero-lateral part of the condyle (Fig 5). No such change was noticed on the contralateral condyle. A similar furrow was noted in the right joint of rabbit 9 (Fig. 3). Histologic examination showed intact cartilage without signs of inflammatory reaction in both cases. Rabbit 3 (Figs. 2a, b) exhibited clearly visible scratches on the central part of the right condyle.
-70 -70
None of the joint sections examined re-
Table 2. Changes in weight after arthroscopy Animal no . 10 9 8 7 6 5 4 3 2 I
Preoperative weight
4030 3400 3400 3530 3380 3540 3850 3490 3650 4450
Dissection
Postoperative weight 5d
7d -80 +90 -30 +300 +180 +280
14 d
28 d
+20 +230 +230 +360 +230 +350
.+260 +300 +530 +550 +500 +620
+ 180 Histological examination
174
HOLMLUND, HELLSING AND BANG
Fig. 6. Rabbit 8, It,ft temporomandibular joint 4 weeks after arthroscopy. Normal appearance with smooth fibrocartilage covering the condylar surface , underlying hyaline cartilag e and subchondral bone, (A); lower compartment, (B); disk, (C); and upper comp artment, (D). HES x23.
vealed any changes of the condylar surfaces and there was no difference between the experimental and control sides concerning the appearance of the fibrocartilage, hyaline cartilage, connective tissue or bone tissue (Fig. 6). In particular, there were no signs of defective morphology or inflammatory cells. A few extravascular red blood cells were occasionally found in the perisynovial tissues of the experimental side but no associated inflammatory reaction was seen.
Discussion The needlescope used in the present study
is the smallest available on the market. Within the tiny structures of the rabbit TMJ, even this instrument is difficult to manipulate. A clear view depended on irrigation under pressure with isotonic saline solution and a properly adjusted light. To facilitate localization of a suitable puncture point, a slight subcutaneous dissection was made lateral to the joint. The applied anaesthetic procedure gave adequate anaesthesia and jaw muscle relaxation, thus facilitating manipulation. Dissection and histology were both employed to detect pathological reactions in the joint tissues. More reliable results than those achieved by histology alone may therefore have been obtained. The findings indicate that arthroscopy may be performed with practically no risk of postoperative complications. This determination is substantiated by the fact that the animals exhibited only small weight losses which were confined ·to the first week , and chewing habits seemed to be consistently unimpaired. In a study on rabbits examined histologically 8 weeks after arthroscopy, HILSABECK & LASKIN (6) arrived at similar conclusions. Only a small furrow in otherwise normal looking cartilage was observed after 28 days on the deliberately scratched condyle of'rabbit 9. The condyle of rabbit 5 also exhibited a similar furrow. The location of the furrows and absence of such changes on the contralateral condyles indicate iatrogenic lesions. Minor damage made by the arthroscope is thus likely to heal without further complications. One may also assume that in human beings , TMJ arthroscopy involves little risk of postoperative complications. Acknowledgement - This study has been supported by the Swedish Dental Society.
References I.
EIKELAAR,
H. R.: Arthroscopy of the knee.
ARTHROSCOPY OF RABBIT JOINT Dissertation. Rijksuniversiteit Groningen Royal United Printers Hoitserna B.V. 1975. 2. ERIKSSO:-:, E., LINDVALL, N., SEBIK, A. & SILFVERSKIOLD, J.: A comparison between arthroscopy and arthrography of the knee. Acta Orthop , Scand. 1981: 52: 126. 3. HELLSING, G ., HOLMLUND, A., NORDENRAM, A. & WRED~IARK, T.: Arthroscopy of the temporomandibular joint. Examination of 2 patients with suspecteddisk derangement. Int. J. Oral Surg, 1984: 13: 67-74. 4. HELLSING, G., HOLMLUND, A., NORDENRAM, A. & WREDMARK, T.: Klikledsartroskopi, Ett nytt hjiilpmedel till fOrbiittrad diagnostik och terapi. Tandliikartidningen 1984: 76: 441-444. 5. HOLMLUND, A. & HELLSING, G.: Arthroscopy of the temporomandibular joint - an autopsy study. Int. J. Oral Surg, 1985: 14: 169-175. 6. HILSABECK, R. B. & LASKIN, B. M.: Arthroscopy of the temporomandibular joint of the rabbit. J. Oral Surg, 1978: 36: 938-943.
175
7. NORWOOD JR., L. A., SIIIELDS, JR., C. L., Russo, J., KERLAND, J. K., JOBE, F. W., CARTER, V. S., BLAZINA, M . E., LmlBARDO, S. J. & DEL PIZZO, \V.: Arthroscopy of the lateral meniscus in knees with normal arthrograms. Am. J. Sports Med. 1977: 5: 271-274. 8. OIINISIII, M.: Clinical application of arthroscopy in the temporomandibular joint diseases. sen. Tokyo Aled. Dent. um« 1980: 27: 141-150 . 9. OIlNISIII, M .: Arthroscopy of the temporomandibular joint (in Japanese). J. Jap. Stomat. 1975: 42: 207-213. Address: Anders Holmlund Department of Oral Surgery Faculty of Odontology Box 4064 14104 Huddinge Sweden
Arthroscopy of the rabbit temporomandibular joint ANDERS HOLMLUND, GUSTAF HELLSING AND GISLE BANG Departments of Oral Surgery and Stomathognatic Physiology, Karolinska Institutet, Huddinge, Sweden and Department of Oral Pathology and Forensic Odontology. Faculty of Dentistry. University of Bergen. Haukeland Hospital. Bergen. Norway
ABSTRACT - Arthroscopy of the rabbit temporomandibular joint was evaluated experimentally on 22 rabbits. A small arthroscope with socalled "Selfoc"-system was employed. The reaction to arthroscopy was analyzed clinically. Macroscopic dissection and histology were then employed to detect possible pathological changes in the joints at periodic intervals. The established criteria for evaluation of postoperative reactions were erythema, suppuration, weight changes and chewing capacity. The results of this study indicate that the rabbit temporomandibular joint may be arthroscoped with subsequent minor reversible changes. It also seems feasible to assume that temporomandibular joint arthroscopy in humans runs a low risk for postoperative complications.
(Accepted for publication 1 December 1984)
Arthroscopy has gained general acceptance as an important and non-injurious aid in knee joint diagnostics'-". Small arthroscopes, so-called needle scopes, permitting access to small joints, are now available. The temporomandibular joint (TMJ) is diffieult to examine clinically and radiographically. The advantage of a diagnostic method allowing inspection and biopsy of internal joint 'structures is thus obvious. In an autopsy study, HOLMLUND & HELLSING S demonstrated a high degree of diagnostic accuracy regarding TMJ arthroscopy. OHNISHI 8,9 and HELLSING et al. 3 ,4 have reported the successful performance of
arthroscopy on humans; however, no systematic evaluation of TMJ arthroscopy has been performed as yet. A histological study of the rabbit TMJ6 indicated good restitution 8 weeks after arthroscopy. In the current study involving rabbits, histology and dissection were employed in order to evaluate the probability of arthroscopic postoperative complications.
Material and methods A total of22 "New Zealand white" rabbits (local breeder, Axell, Eked), Sweden) of both sexes and
ARTHROSCOPY OF RABBIT JOINT Table I. Group distribution and observation time Rabbit Observano. tion time 5 days 1,3 group I dissection 2,4 histology 28 days group II dissection 5,7,9 histology 6,8,10 all more than 3 Y, months old were utilized in the study. 10 of these rabbits were used in a pilot study, their joints being dissected and anatomically investigated. 2 other rabbits were used on 4 occasions in order to establish a reliable anaesthetic procedure and arthroscopic technique. The 10 remaining rabbits were employed in the experiments described below. Table I illustrates the group distribution. Arthroscopy was performed on one side, with the contralateral joint as control. After postoperative observation periods of 5 days (group I) and 28 days (group II), the animals were sacrificed. Macroscopic dissection was performed on every second rabbit (Table 1). If changes appeared to be pathological, the specimen underwent histological examination. The joints of rabbits 2, 4, 6, 8 and 10were examined only histologically (Table I). All rabbits were maintained on a standard diet of pellets and water ad libitum. The experimental rabbits were individually housed in a c1imatecontrolled animal facility (50% RH, dark/light schedule 12/12). Arthroscopy A needlescope with the "Selfoc"-system (Olympus Optical Co, Tokyo) was used. It consisted of
Fig. 1. The needlescope used in the present study.
171
2 trocars, a cannula and telescope with connected fibre optic cable (Fig. I). The telescope had a diameter of 1.7 mrn, surrounded by the cannula, diameter 2.0 mm). The viewing lens had an optical inclination of 16°. The arthroscope was connected to a light source with enclosed electronic flash (Karl Storz GmbH Co, D-7200 Tuttlingen). Glutaraldehyde solution (2%) was used for sterilization. The rabbits were anaesthetized by intramuscular injection of a neurolept analgesic combination of fentanyl-fluanizone with diazepam. In all rabbits the lower joint compartment was investigated. The upper compartment of rabbit I was also examined. Hair overlying the TMJ was shaved with an electric razor and the skin scrubbed with antiseptic soap. The TMJ and a suitable puncture point were localized by palpation. A small needle was then inserted and advanced toward the condyle in antero-inferior direction until resistance was detected. The lower joint compartment was distended by
Fig Za. Arthroscopic view of the postero-lateral
portion of the right condyle of rabbit 3; posterior portion of the disk upper most. Arrow indicates a small piece of torn off cartilage.
Fig. lb. The same condyle during dissection with clearly visible scratches.
172
HOLMLUND, HELLSING AND BANG
Fig. 3. The right condyle of rabbit 9 during dissection. A small but distinct furrow is seen on the lateral portion of the condyle (arrow).
injection of an isotonic saline solution. A small incision was made through the skin and the subcutaneous tissue lateral to the joint capsule identified. The capsule of the lower compartment was then punctured by the sharp trocar. The latter was subsequently exchanged for a blunt trocar and the cannula further introduced into the joint cavity. The trocar was finally replaced by the telescope and the joint examined. Consistent distention and a clear view was achieved by irrigation of the joint cavity with an isotonic saline solution. Scratches were deliberately made on the condylar cartilage in rabbit 3, group I, and rabbit 9, group II, using the sharp trocar, Figs. 2a,b and 3. Arthroscopic photographs were obtained using an SLR camera (Nikkon F3 Nippon Koga Ku K.K ., Tokyo Japan) with a special endoscopy lens (Karl Storz GmbH Co) and Ektachrome 400 ASA daylight films. The wound was closed with I or 2 no. 4-0 polyglycolic acid sutures. No antibiotics or other drugs were administered postoperatively. After recovery from anaesthesia the rabbits were immediately returned to their cages. The response to arthroscopy was evaluated according to 4 criteria: erythema, suppuration, weight changes and chewing capacity. Erythema and suppuration were judged to be either present or absent and were evaluated on days 1,2, 5, 7, 14, 21 and 28. Weight was registered preoperatively and after 5 days in group 1. In group II, weight was registered preoperatively and at I, 2, 3 and 4 weeks. A piece of wood was used postoperatively to test chewing capacity. Pellets and water consumption and gnawing behaviour were employed as measures of normal chewing capacity. The animals in groups I and II were
sacrified after 5 and 28 days, respectively, by means of an intravenous overdose of barbiturate. The TMJ's were immediately removed en bloc with preserved joint capsules. Both joints of rabbits I, 3, 5, 7 and 9 were dissected and each pair compared macroscopically. Photographic documentation was obtained with a Nikkon Medicam camera and Ektachrome 64 ASA daylight film. On rabbits 2, 4, 6, 8 and 10, the TMJ preparation was placed in 5% neutral buffered formalin. Approximately 2 mm thick sagittal sections from the midline were cut by means of a rotating sawtoothed disk under water cooling. The specimens were demineralized in 4N formic acid, dehydrated, embedded in paraffin, cut at 3-4 p and stained with hematoxylin, eosin and saffranin. The sections were evaluated blind, i.e., without prior knowledge of the experimental protocol.
Results In the pilot study, joint position was found to be more superficial than in humans. Except for smaller dimension, the gross anatomy and structural appearance were similar to corresponding features of the human TMJ. Left and right joints of each rabbit displayed a symmetric appearance, and there were only small inter-individual variations in the anatomy.
Fig. 4a. Rabbit 2, right joint. Arthroscopic view of the central part ' of the lower compartment. Disk upper most. To the left (arrow) a small tornoff piece of the condylar cartilage.
ARTHROSCOPY OF RABBIT JOINT
Fig. 4b. A more anterior view of the same joint compartment.
Arthroscopic observations
The condylar and inferior disk surfaces and the posterior disk attachment were investigated in all cases. Additionally, in rabbit 1 the upper compartment was also examined. The richly vascularized synovial tissue differed radically from the glistening but pale and avascular surfaces of the condyle, disk and fossa. Figs. 4a, b show typical arthroscopic views.
173
Fig. 5. Rabbit 5, right condyle during dissection. A small furrow in the supero-Iateral portion of the condyle (arrow).
No sign of suppuration was found in any of the cases examined . Table 2 illustrates weight changes. 2 of the animals, sacrificed after 5 days, group I, exhibited slight weight loss. In group II, 2 rabbits experienced a slight weight reduction by day 7. After 2 and 4 weeks, all the rabbits in group II had normal weight, (X = +460 g, range 260-620 g). Daily observations indicated no impairment in the ability to eat pellets or drink water. All gnawed on the pieces of wood offered postoperatively and seemed to maintain good general health.
Clinical observations
Postoperative erythema at the site of incision was observed on rabbit 3 for 2 days.
+110
No pathological changes were observed in the temporal fossa or disk. In rabbit 5 (right joint), a small but distinct furrow with intact cartilage was observed in the supero-lateral part of the condyle (Fig 5). No such change was noticed on the contralateral condyle. A similar furrow was noted in the right joint of rabbit 9 (Fig. 3). Histologic examination showed intact cartilage without signs of inflammatory reaction in both cases. Rabbit 3 (Figs. 2a, b) exhibited clearly visible scratches on the central part of the right condyle.
-70 -70
None of the joint sections examined re-
Table 2. Changes in weight after arthroscopy Animal no . 10 9 8 7 6 5 4 3 2 I
Preoperative weight
4030 3400 3400 3530 3380 3540 3850 3490 3650 4450
Dissection
Postoperative weight 5d
7d -80 +90 -30 +300 +180 +280
14 d
28 d
+20 +230 +230 +360 +230 +350
.+260 +300 +530 +550 +500 +620
+ 180 Histological examination
174
HOLMLUND, HELLSING AND BANG
Fig. 6. Rabbit 8, It,ft temporomandibular joint 4 weeks after arthroscopy. Normal appearance with smooth fibrocartilage covering the condylar surface , underlying hyaline cartilag e and subchondral bone, (A); lower compartment, (B); disk, (C); and upper comp artment, (D). HES x23.
vealed any changes of the condylar surfaces and there was no difference between the experimental and control sides concerning the appearance of the fibrocartilage, hyaline cartilage, connective tissue or bone tissue (Fig. 6). In particular, there were no signs of defective morphology or inflammatory cells. A few extravascular red blood cells were occasionally found in the perisynovial tissues of the experimental side but no associated inflammatory reaction was seen.
Discussion The needlescope used in the present study
is the smallest available on the market. Within the tiny structures of the rabbit TMJ, even this instrument is difficult to manipulate. A clear view depended on irrigation under pressure with isotonic saline solution and a properly adjusted light. To facilitate localization of a suitable puncture point, a slight subcutaneous dissection was made lateral to the joint. The applied anaesthetic procedure gave adequate anaesthesia and jaw muscle relaxation, thus facilitating manipulation. Dissection and histology were both employed to detect pathological reactions in the joint tissues. More reliable results than those achieved by histology alone may therefore have been obtained. The findings indicate that arthroscopy may be performed with practically no risk of postoperative complications. This determination is substantiated by the fact that the animals exhibited only small weight losses which were confined ·to the first week , and chewing habits seemed to be consistently unimpaired. In a study on rabbits examined histologically 8 weeks after arthroscopy, HILSABECK & LASKIN (6) arrived at similar conclusions. Only a small furrow in otherwise normal looking cartilage was observed after 28 days on the deliberately scratched condyle of'rabbit 9. The condyle of rabbit 5 also exhibited a similar furrow. The location of the furrows and absence of such changes on the contralateral condyles indicate iatrogenic lesions. Minor damage made by the arthroscope is thus likely to heal without further complications. One may also assume that in human beings , TMJ arthroscopy involves little risk of postoperative complications. Acknowledgement - This study has been supported by the Swedish Dental Society.
References I.
EIKELAAR,
H. R.: Arthroscopy of the knee.
ARTHROSCOPY OF RABBIT JOINT Dissertation. Rijksuniversiteit Groningen Royal United Printers Hoitserna B.V. 1975. 2. ERIKSSO:-:, E., LINDVALL, N., SEBIK, A. & SILFVERSKIOLD, J.: A comparison between arthroscopy and arthrography of the knee. Acta Orthop , Scand. 1981: 52: 126. 3. HELLSING, G ., HOLMLUND, A., NORDENRAM, A. & WRED~IARK, T.: Arthroscopy of the temporomandibular joint. Examination of 2 patients with suspecteddisk derangement. Int. J. Oral Surg, 1984: 13: 67-74. 4. HELLSING, G., HOLMLUND, A., NORDENRAM, A. & WREDMARK, T.: Klikledsartroskopi, Ett nytt hjiilpmedel till fOrbiittrad diagnostik och terapi. Tandliikartidningen 1984: 76: 441-444. 5. HOLMLUND, A. & HELLSING, G.: Arthroscopy of the temporomandibular joint - an autopsy study. Int. J. Oral Surg, 1985: 14: 169-175. 6. HILSABECK, R. B. & LASKIN, B. M.: Arthroscopy of the temporomandibular joint of the rabbit. J. Oral Surg, 1978: 36: 938-943.
175
7. NORWOOD JR., L. A., SIIIELDS, JR., C. L., Russo, J., KERLAND, J. K., JOBE, F. W., CARTER, V. S., BLAZINA, M . E., LmlBARDO, S. J. & DEL PIZZO, \V.: Arthroscopy of the lateral meniscus in knees with normal arthrograms. Am. J. Sports Med. 1977: 5: 271-274. 8. OIINISIII, M.: Clinical application of arthroscopy in the temporomandibular joint diseases. sen. Tokyo Aled. Dent. um« 1980: 27: 141-150 . 9. OIlNISIII, M .: Arthroscopy of the temporomandibular joint (in Japanese). J. Jap. Stomat. 1975: 42: 207-213. Address: Anders Holmlund Department of Oral Surgery Faculty of Odontology Box 4064 14104 Huddinge Sweden