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Ultrathin arthroscope for use in the lower compartment of the temporomandibular joint
Ultrathin arthroscope for use in the lower compartment of the temporomandibular joint Toshirou Kondoh, DDS, PhD,a and Per-Lennart Yokohama, Japan, and Rochester, N.Y. TSURUMI UNIVERSITY
AND UNIVERSITY
Westesson, DDS, PhD,b
OF ROCHESTER
Arthroscopy of the temporomandibular joint has been performed mainly in the upper joint space because the instruments available have been too thick to be safely inserted into the lower joint space. This article describes a newly developed ultrathin arthroscope with an outer diameter of 0.69 mm that has been specifically developed to be used in the lower space of the temporomandibular joint. This arthroscope can be inserted into the lower joint space with a standard 18-gauge needle. The article describes the arthroscope in its initial application to patient and cadaver material. (ORAL SURG ORAL MED ORAL PATHOL 1991;72:146-9)
T
he first report on arthroscopy of the temporomandibular joint (TMJ) appeared in the Japanese literature in 1975.‘~ 2 A 1.7 mm arthroscope inserted into a 2.0 mm arthroscopic cannula was used to visualize the intra-articular anatomy of the upper joint space. It took about 6 to 8 years before arthroscopy of the TMJ gained wider clinical acceptance.3-‘0 The main reason for the changed attitude toward TMJ arthroscopy and the more extensive clinical use of the technique was the identification of intra-articular fibrous adhesive bands, which were thought to be associated with the patient’s symptoms of pain and limitation of opening. 1’ Arthroscopy has been performed mainly in the upper joint space because the thickness of the instruments (22 mm) has prevented the safe introduction into the lower joint spaces3 This has been a significant drawback of arthroscopy, because pathologic changes in the lower joint space would not have been identified.
Supported by the Torsten and Ragnar Siiderberg Foundations, Stockholm, Sweden. BFirst Department of Oral and Maxillofacial Surgery, School of Dentistry, Tsurumi University, Yokohama. bDepartments of Radiology and Clinical Dentistry, University of Rochester School of Medicine and Dentistry, and Department of Orthodontics, Eastman Dental Center, Rochester. 7/12/28235 146
To overcome this limitation, an ultrathin arthroscope was developed in collaboration with the J. Morita Co., Kyoto, Japan, and Sumitomo Electric Industries, Yokohama, Japan. This ultrathin arthroscope can be inserted into the lower space of the TMJ with a standard 18-gauge needle. This article describes the new arthroscope and its initial application to patient and cadaver joints. MATERIAL AND METHODS
The arthroscope (Figs. 1 to 4) was made of optic fibers built into a stainless steel cannula with an outer diameter of 0.69 mm. In the tube were 3000 optic fibers, resulting in 3000 picture elements (pixels). At the tip of the arthroscope was an optic lens with a focus of 2.4 mm. This lens was used to increase the field of view to 70 degrees in air. The focusing point of the arthroscope was 2 mm. Irrigation of the joint space was done with an irrigation port applied between the 18-gauge arthroscopic cannula and the arthroscope (Figs. 1 and 2). The irrigation fluid was injected into the joint through the space between the inner surface of the 18-gauge needle and the outer surface of the arthroscope. The length of the probe of the arthroscope was 70 mm. The total length of the arthroscope was 155 mm, including the attachment to the video camera. The maximal thickness of the arthroscope was 25 mm.
Ultrathin
Volume 72 Number 2 Irrigation Port ,
Conn’ecting Ring
Adjustable Ring
Fig.
arthroscope for lower TMJ space 147
Arthroscopic Neede Canula
Fibro-optic Needle Scope
1. Technical drawing of arthroscope.
3. Control box, CCD video camera, arthroscope, arthroscopic needle, cannula, and guiding pin.
Fig.
FibrA-optic Needle Scope
Fig.
Arthrdscopic Needle Canula
2. Cross section of arthroscope.
A specific charge-coupled
device (CCD) video camera (Fig. 3) was constructed to be attached directly to the arthroscope. The dimension of the camera was 98.5 X 24.5 mm. The camera was connected to a control and light box with a 9.5 X 2000 mm fiber-optic light cable. The total weight of the camera and cable was 260 gm. A 12.5 mm CCD image sensor was built into the camera. The resolution of the sensor was 360 TV X 350 TV with National Television Standard Commission standards. A focusing ring was on the camera. The camera was attached to the arthroscope by a one-touch locking mechanism. The light source for this arthroscope used a 50 W halogen lamp (Fig. 4). In the prototype described in this study the light control was manual, but it is the intention to make the light control automatic. The arthroscope was gas sterilized. The CCD video camera was not sterilized but was instead covered with tube drapes. In this study the arthroscope was used in the examination of three cadaver joints and three patients who subsequently underwent open joint
surgery. RESULTS
The arthroscope was inserted into the posterior re-
cess of the lower joint space with an 18-gauge needle.
4. Arthroscope and CCD video camera separated from arthroscope, arthroscopic needle, cannula, and guiding pin.
Fig.
The anterior recess of the lower joint space was also punctured with another 18-gauge needle. By moving the arthroscope to this anterior needle it was also possible to inspect the anterior recess of the lower joint space. The intra-articular anatomy of the posterior, superior, and the anterior parts of the lower joint space in a cadaver TMJ were well visualized (Fig. 5). Examples of arthroscopic diagnosis of a perforation are seen in Fig. 6. In this small sample of three patients and three cadaver joints, agreement was generally good between what was seen arthroscopically and during the following open joint surgery. No complications arose from the arthroscopic examinations. DISCUSSION
The results of this study suggest that it is possible to examine the intra-articular anatomy of the lower space of the TMJ with this newly developed ultrathin arthroscope. This is a major step forward in the area of TMJ arthroscopy; it had not been possible in earlier studies to routinely examine the lower joint space,
148
Kondoh and Westesson
ORAL
SURG
ORAL
MED
ORAL PATHOL. August 199 I
Fig. 5. Arthroscopic views of anterior (A), central (B), and posterior(C) parts of lower joint space of normal cadaver. Lower surface of disk (D), joint space (J), and condyle (C) are indicated. PA, Posterior attachment.
Fig. 6. Arthroscopic image of lower joint space showing perforation. Condyle (C), lower joint space (U), disk (D), upper joint space (UJ), and tubercle (T) are indicated. Margin of perforation is indicated by arrows.
because the existing instruments were too thick to be safely inserted into the lower joint space. In the past, thin arthroscopic instruments have been extremely fragile. This has been overcome to some degree with the use of fiber optics instead of rod lenses. An instrument based on fiber optics allows for some bending of the arthroscopic probe without damage. The optical quality of a fiber-optic system has not been as good as that of a rod lens system,3 but we have been impressed by the image quality obtained with this instrument, especially in view of its diameter of
only 0.69 mm. The relatively high quality of the arthroscopic images was the result of having 3000 thin optic fibers instead of fewer but thicker optic fibers. A limitation of this arthroscope is obviously the narrow field of vision (70 degrees). To some extent this could be compensated for by elaborate movements of the arthroscope and the use of two different entrances. Our initial experience with this arthroscope is encouraging, but before this arthroscope is introduced into clinical work, it should be examined for its accuracy, sensitivity, and safety. Thus diagnostic accuracy, sensitivity, and specificity should be established under experimental conditions and the risk for iatrogenie damage to the articular surfaces and to the disk should be investigated. In conclusion, an ultrathin arthroscope with an outer diameter of 0.69 mm has been developed to be used in the lower space of the TMJ. The initial results from application on a few patients and a few cadaver joints have been encouraging, with surprisingly good image quality and good ability to visualize the different areas of the intra-articular anatomy. Further systematic evaluation of diagnostic accuracy and risk of iatrogenic damage is warranted before this instrument is applied clinically. We acknowledge Nils-Herman Sternby, MD, PhD, Department of Pathology, MalmG General Hospital, Malmii, Sweden, for assistance in obtaining cadaver material for this study. REFERENCES 1. Onishi M. Arthroscopy of the temporomandibular joint. J Jpn Stomatol Assoc 1975;42:207-I 3. 2. Onishi M. Clinical application of arthroscopy in the temporomandibular joint diseases. Bull Tokyo Med Dent Univ 1980; 27:141-50.
Ultrathin
Volume 72 Number 2 3. Holmlund A, Hellsing G. Arthroscopy of the temporomandibular joint: an autopsy study. Int J Oral Surg 1985;14:169-75. 4. Eriksson L, Westesson P-L. Deterioration of temporary silicone implant in the temporomandibular joint: a clinical and arthroscopic follow-up study. ORAL SURG ORAL MED ORAL PATHOL 1986;62:2-6. 5. Goss AN, Bosanquet AG. Temporomandibular joint arthroscopy. J Oral Maxillofac Surg 1986;44:614-7. 6. Murakami K, Ono T. Temporomandibular joint arthroscopy by inferolateral approach. Int J Oral Maxillofac Surg 1986; 15:410-7. 7. McCain JP. Arthroscopy of the human temporomandibular joint. J Oral Maxillofac Surg 1988;46:648-55. 8. lndresano AT. Arthroscopic surgery of the temporomandibular joint: report of 64 patients with long-term follow-up. J Oral Maxillofac Surg 1989;47:439-41.
BOUND VOLUMES
AVAILABLE
arthroscope for lower TMJ space 149
9. Moses JJ, Poker ID. Temporomandibular joint arthroscopy: the endaural approach. Int J Oral Maxillofac Surg 1989; 18:347-51. 10. Montgomery MT, Van Sickels JE, Harms SE, Thrash WJ. Arthroscopic TMJ surgery: effects of signs, symptoms, and disc position. J Oral Maxillofac Surg 1989;47: 1263-71. I 1. Sanders B. Artbroscopic surgery of the temporomandibular joint: treatment of internal derangement with persistent closed lock. ORAL SURC ORAL MED ORAL PATHOL 1986;62:361-72. Reprint
requests:
Toshirou Kondoh, DDS, PhD Division of Oral and Maxillofacial Yokohema Rosai Hospital 3211 Kozukue-cho, Kouhoku-ku Yokohama, Japan
Surgery
TO SUBSCRIBERS
Bound volumes of ORAL SURGERY,ORAL MEDICINE, AND ORAL PATHOLOGYare available to subscribers (only) for the 1991 issues from the Publisher, at a cost of $45.00 for domestic, $60.15 for Canadian, and $57.00 for international, for Vol. 71 (January-June) and Vol. 72 (July-December). Shipping charges are included. Each bound volume contains a subject and author index and all advertising is removed. Copies are shipped within 60 days after publication of the last issue in the volume. The binding is durable buckram with the journal name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact Mosby-Year Book, Inc., Subscription Services, 11830 Westline Industrial Drive, St. Louis, MO 63146-3318, USA, phone (800)325-4177, ext. 4351. Subscriptions must be in force to qualify.
Bound
volumes
are not available
in place of a regular
journal
subscription.
AND UNIVERSITY
Westesson, DDS, PhD,b
OF ROCHESTER
Arthroscopy of the temporomandibular joint has been performed mainly in the upper joint space because the instruments available have been too thick to be safely inserted into the lower joint space. This article describes a newly developed ultrathin arthroscope with an outer diameter of 0.69 mm that has been specifically developed to be used in the lower space of the temporomandibular joint. This arthroscope can be inserted into the lower joint space with a standard 18-gauge needle. The article describes the arthroscope in its initial application to patient and cadaver material. (ORAL SURG ORAL MED ORAL PATHOL 1991;72:146-9)
T
he first report on arthroscopy of the temporomandibular joint (TMJ) appeared in the Japanese literature in 1975.‘~ 2 A 1.7 mm arthroscope inserted into a 2.0 mm arthroscopic cannula was used to visualize the intra-articular anatomy of the upper joint space. It took about 6 to 8 years before arthroscopy of the TMJ gained wider clinical acceptance.3-‘0 The main reason for the changed attitude toward TMJ arthroscopy and the more extensive clinical use of the technique was the identification of intra-articular fibrous adhesive bands, which were thought to be associated with the patient’s symptoms of pain and limitation of opening. 1’ Arthroscopy has been performed mainly in the upper joint space because the thickness of the instruments (22 mm) has prevented the safe introduction into the lower joint spaces3 This has been a significant drawback of arthroscopy, because pathologic changes in the lower joint space would not have been identified.
Supported by the Torsten and Ragnar Siiderberg Foundations, Stockholm, Sweden. BFirst Department of Oral and Maxillofacial Surgery, School of Dentistry, Tsurumi University, Yokohama. bDepartments of Radiology and Clinical Dentistry, University of Rochester School of Medicine and Dentistry, and Department of Orthodontics, Eastman Dental Center, Rochester. 7/12/28235 146
To overcome this limitation, an ultrathin arthroscope was developed in collaboration with the J. Morita Co., Kyoto, Japan, and Sumitomo Electric Industries, Yokohama, Japan. This ultrathin arthroscope can be inserted into the lower space of the TMJ with a standard 18-gauge needle. This article describes the new arthroscope and its initial application to patient and cadaver joints. MATERIAL AND METHODS
The arthroscope (Figs. 1 to 4) was made of optic fibers built into a stainless steel cannula with an outer diameter of 0.69 mm. In the tube were 3000 optic fibers, resulting in 3000 picture elements (pixels). At the tip of the arthroscope was an optic lens with a focus of 2.4 mm. This lens was used to increase the field of view to 70 degrees in air. The focusing point of the arthroscope was 2 mm. Irrigation of the joint space was done with an irrigation port applied between the 18-gauge arthroscopic cannula and the arthroscope (Figs. 1 and 2). The irrigation fluid was injected into the joint through the space between the inner surface of the 18-gauge needle and the outer surface of the arthroscope. The length of the probe of the arthroscope was 70 mm. The total length of the arthroscope was 155 mm, including the attachment to the video camera. The maximal thickness of the arthroscope was 25 mm.
Ultrathin
Volume 72 Number 2 Irrigation Port ,
Conn’ecting Ring
Adjustable Ring
Fig.
arthroscope for lower TMJ space 147
Arthroscopic Neede Canula
Fibro-optic Needle Scope
1. Technical drawing of arthroscope.
3. Control box, CCD video camera, arthroscope, arthroscopic needle, cannula, and guiding pin.
Fig.
FibrA-optic Needle Scope
Fig.
Arthrdscopic Needle Canula
2. Cross section of arthroscope.
A specific charge-coupled
device (CCD) video camera (Fig. 3) was constructed to be attached directly to the arthroscope. The dimension of the camera was 98.5 X 24.5 mm. The camera was connected to a control and light box with a 9.5 X 2000 mm fiber-optic light cable. The total weight of the camera and cable was 260 gm. A 12.5 mm CCD image sensor was built into the camera. The resolution of the sensor was 360 TV X 350 TV with National Television Standard Commission standards. A focusing ring was on the camera. The camera was attached to the arthroscope by a one-touch locking mechanism. The light source for this arthroscope used a 50 W halogen lamp (Fig. 4). In the prototype described in this study the light control was manual, but it is the intention to make the light control automatic. The arthroscope was gas sterilized. The CCD video camera was not sterilized but was instead covered with tube drapes. In this study the arthroscope was used in the examination of three cadaver joints and three patients who subsequently underwent open joint
surgery. RESULTS
The arthroscope was inserted into the posterior re-
cess of the lower joint space with an 18-gauge needle.
4. Arthroscope and CCD video camera separated from arthroscope, arthroscopic needle, cannula, and guiding pin.
Fig.
The anterior recess of the lower joint space was also punctured with another 18-gauge needle. By moving the arthroscope to this anterior needle it was also possible to inspect the anterior recess of the lower joint space. The intra-articular anatomy of the posterior, superior, and the anterior parts of the lower joint space in a cadaver TMJ were well visualized (Fig. 5). Examples of arthroscopic diagnosis of a perforation are seen in Fig. 6. In this small sample of three patients and three cadaver joints, agreement was generally good between what was seen arthroscopically and during the following open joint surgery. No complications arose from the arthroscopic examinations. DISCUSSION
The results of this study suggest that it is possible to examine the intra-articular anatomy of the lower space of the TMJ with this newly developed ultrathin arthroscope. This is a major step forward in the area of TMJ arthroscopy; it had not been possible in earlier studies to routinely examine the lower joint space,
148
Kondoh and Westesson
ORAL
SURG
ORAL
MED
ORAL PATHOL. August 199 I
Fig. 5. Arthroscopic views of anterior (A), central (B), and posterior(C) parts of lower joint space of normal cadaver. Lower surface of disk (D), joint space (J), and condyle (C) are indicated. PA, Posterior attachment.
Fig. 6. Arthroscopic image of lower joint space showing perforation. Condyle (C), lower joint space (U), disk (D), upper joint space (UJ), and tubercle (T) are indicated. Margin of perforation is indicated by arrows.
because the existing instruments were too thick to be safely inserted into the lower joint space. In the past, thin arthroscopic instruments have been extremely fragile. This has been overcome to some degree with the use of fiber optics instead of rod lenses. An instrument based on fiber optics allows for some bending of the arthroscopic probe without damage. The optical quality of a fiber-optic system has not been as good as that of a rod lens system,3 but we have been impressed by the image quality obtained with this instrument, especially in view of its diameter of
only 0.69 mm. The relatively high quality of the arthroscopic images was the result of having 3000 thin optic fibers instead of fewer but thicker optic fibers. A limitation of this arthroscope is obviously the narrow field of vision (70 degrees). To some extent this could be compensated for by elaborate movements of the arthroscope and the use of two different entrances. Our initial experience with this arthroscope is encouraging, but before this arthroscope is introduced into clinical work, it should be examined for its accuracy, sensitivity, and safety. Thus diagnostic accuracy, sensitivity, and specificity should be established under experimental conditions and the risk for iatrogenie damage to the articular surfaces and to the disk should be investigated. In conclusion, an ultrathin arthroscope with an outer diameter of 0.69 mm has been developed to be used in the lower space of the TMJ. The initial results from application on a few patients and a few cadaver joints have been encouraging, with surprisingly good image quality and good ability to visualize the different areas of the intra-articular anatomy. Further systematic evaluation of diagnostic accuracy and risk of iatrogenic damage is warranted before this instrument is applied clinically. We acknowledge Nils-Herman Sternby, MD, PhD, Department of Pathology, MalmG General Hospital, Malmii, Sweden, for assistance in obtaining cadaver material for this study. REFERENCES 1. Onishi M. Arthroscopy of the temporomandibular joint. J Jpn Stomatol Assoc 1975;42:207-I 3. 2. Onishi M. Clinical application of arthroscopy in the temporomandibular joint diseases. Bull Tokyo Med Dent Univ 1980; 27:141-50.
Ultrathin
Volume 72 Number 2 3. Holmlund A, Hellsing G. Arthroscopy of the temporomandibular joint: an autopsy study. Int J Oral Surg 1985;14:169-75. 4. Eriksson L, Westesson P-L. Deterioration of temporary silicone implant in the temporomandibular joint: a clinical and arthroscopic follow-up study. ORAL SURG ORAL MED ORAL PATHOL 1986;62:2-6. 5. Goss AN, Bosanquet AG. Temporomandibular joint arthroscopy. J Oral Maxillofac Surg 1986;44:614-7. 6. Murakami K, Ono T. Temporomandibular joint arthroscopy by inferolateral approach. Int J Oral Maxillofac Surg 1986; 15:410-7. 7. McCain JP. Arthroscopy of the human temporomandibular joint. J Oral Maxillofac Surg 1988;46:648-55. 8. lndresano AT. Arthroscopic surgery of the temporomandibular joint: report of 64 patients with long-term follow-up. J Oral Maxillofac Surg 1989;47:439-41.
BOUND VOLUMES
AVAILABLE
arthroscope for lower TMJ space 149
9. Moses JJ, Poker ID. Temporomandibular joint arthroscopy: the endaural approach. Int J Oral Maxillofac Surg 1989; 18:347-51. 10. Montgomery MT, Van Sickels JE, Harms SE, Thrash WJ. Arthroscopic TMJ surgery: effects of signs, symptoms, and disc position. J Oral Maxillofac Surg 1989;47: 1263-71. I 1. Sanders B. Artbroscopic surgery of the temporomandibular joint: treatment of internal derangement with persistent closed lock. ORAL SURC ORAL MED ORAL PATHOL 1986;62:361-72. Reprint
requests:
Toshirou Kondoh, DDS, PhD Division of Oral and Maxillofacial Yokohema Rosai Hospital 3211 Kozukue-cho, Kouhoku-ku Yokohama, Japan
Surgery
TO SUBSCRIBERS
Bound volumes of ORAL SURGERY,ORAL MEDICINE, AND ORAL PATHOLOGYare available to subscribers (only) for the 1991 issues from the Publisher, at a cost of $45.00 for domestic, $60.15 for Canadian, and $57.00 for international, for Vol. 71 (January-June) and Vol. 72 (July-December). Shipping charges are included. Each bound volume contains a subject and author index and all advertising is removed. Copies are shipped within 60 days after publication of the last issue in the volume. The binding is durable buckram with the journal name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact Mosby-Year Book, Inc., Subscription Services, 11830 Westline Industrial Drive, St. Louis, MO 63146-3318, USA, phone (800)325-4177, ext. 4351. Subscriptions must be in force to qualify.
Bound
volumes
are not available
in place of a regular
journal
subscription.