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The diagnosis and treatment of the dislocated mandible
The Diagnosis and Treatment of the Dislocated Mandible NEIL H. LUYK, BDS, MS,*t Dislocation of the mandible occurs commonly. Most patients present to the emergency department for treatment. This article discusses the normal temporomandlbular joint (TMJ) anatomy and the etiology, types, and diagnosis of mandibular dislocation. It also describes the initial management, includingtechniquesfor nduction of the acute anteriorly dislocated mandible. (Am J Emerg Med 1989;7:32g-335. 0 1989 by W.8. Saunders Company.)
Dislocation of the temporomandibular joint (TMJ) is the displacement of the mandibular condylar head completely out of the glenoid fossa which cannot be reduced by the patient. This condition occurs relatively commonly and patients often present initially to the emergency department for treatment. The purpose of this article is to review the normal anatomy and function of the TMJ and to describe the different types of dislocations of the mandible, their clinical and radiograph diagnosis, and the initial management of the condition. The TMJ is a ginglymoarthrodial joint, implying that it combines a hinge and gliding action. It is derived embryologically from two blastomas: the temporal, which forms the glenoid fossa, and the condylar, which forms the condylar head. The articular surface of the temporal bone consists of the mandibular fossa and, anteriorly, the articular tubercle. The condyle of the mandible is rounded in an anteroposterior dimension, but resembles a narrow ellipsoid in its larger
From the “University of Otago, Dunedin, New Zealand; and the tDepartment of Oral and Maxillofacial Surgery, The Ohio State University College of Dentistry. Manuscript 1988.
received April 21, 1988; revision accepted
July 1,
Address reprint requests to Dr Luyk: Department of Oral Medicine and Oral Surgery, School of Dentistry, PO Box 847, Dunedin, New Zealand. Key Words: Mandible, mandibular joint.
jaw, dislocation,
0 1989 by W.B. Saunders Company. 07358757/89/0703-0019$5.00/O
subluxation,
temporo-
PETER E. LARSEN, DDSt
transverse dimension. The articular surfaces are covered by fibrocartilage instead of hyaline cartilage and are separated and made more congruent by an articular disk (or meniscus) composed of dense fibrous connective tissue. A portion of the lateral pterygoid muscle inserts into the anterior portion of the disk. The capsule of the TMJ is thin and loose. It is attached above to the circumference of the mandibular fossa and the articular tubercle and below to the neck of the condyle of the mandible. The capsule contains one strengthening ligament on its lateral surface. The lateral ligament is broad above where it attaches to the lower border of the zygoma and the tubercle. Its fibers are directed downward and backward to the lateral and posterior parts of the neck of the mandible. There are two accessory ligaments medially, the sphenomandibular and stylomandibular ligaments. The sphenomandibular ligament is thin and flat but very strong. It descends from the spine of the sphenoid bone to the lingula on the medial aspect of the mandible. The stylomandibular ligament is a thickening at the deep parotid fascia which extends from near the end of the styloid process to the posterior border of the ramus of the mandible near its angle. The form of the articulating surfaces is such as to facilitate a hinge action between the articular disk and the mandibular condyle in the lower cavity of the joint and a gliding action between the disk and the temporal bone in the upper cavity. The jaws are opened by forward traction on the neck of the mandible by the lower portion of the lateral pterygoid muscles, assisted by the digastric, mylohyoid, and geniohyoid muscles. The combined gliding and hinge action at this joint produces rotation of the mandible around a transverse axis which might be projected between the two lingulae. Closure of the jaws is a very powerful action produced by the combined action of the masseter, the medial pterygoid, and the temporalis muscles. The medial pterygoid muscle assists the lateral pterygoid in protrusion of the mandible. The posterior fibers of the temporalis control retrusion assisted by the suprahyoid group of muscles. Lateral excursion of the mandible is largely by the unopposed action of one of the lateral pterygoid muscles. 329
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MANDIBULAR DISLOCATION The mandibular condylar can be dislocated into a variety of positions’: anterior, posterior, lateral, and superior. Anterior dislocation occurs when the condyle moves anterior to the articular eminence. This is by far the most common situation, representing a pathologic forward extension of the normal translational movement of the condylar head. In posterior dislocation the mandibular condyle is displaced backward. It usually is associated with a coexistent fracture of the base of the skull or the anterior wall of the bony meatus of the ear. Lateral dislocation can be divided into type 1, lateral subluxation and type 2, a complete dislocation in which the condyle is forced laterally and then superiorly to enter the temporal space. Lateral dislocation requires a concomitant fracture of the body of the mandible. Superior dislocation is associated with a fracture of the glenoid fossa, with displacement of the condyle into the middle cranial fossa.
Anterior Dislocation Subluxation implies displacement that can be reduced by the patient. In as many as 70% of normal patients the condylar head routinely translates anterior to the articular eminence of the temporal bone and reduces spontaneously.* Three contributing factors interact to predispose an individual to symptomatic anterior mandibular condylar dislocation: capsular integrity, articular eminence morphology, and muscle tonicity. Capsular integrity is altered by acute or chronic mandibular hyperextension such as occurs with epileptic seizure, oroendotracheal intubation, or prolonged intraoral operative procedures. Repetitive episodes of mandibular hyperextension may induce a gradual loss of TMJ capsular integrity which permits
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condylar subluxation to become progressively worse until dislocation occurs. Morphologic changes which cause a shallow eminence readily permit translation of the mandibular condyle over the articular eminence, but seldom result in traumatic dislocation. Hypertonicity of the masticatory musculature may result from phenomena such as bruxism or other parafunctional masticatory habits that induce muscle fatigue.3 Anterior dislocation of the mandible is relatively common and can be divided into three subgroups depending on how long it has been present and the frequency with which it occurs: acute, chronic recurrent, and chronic prolonged.
Acute Dislocations The majority of patients with dislocations present with an acute dislocation because of the painful nature of the condition. The condition is usually bilateral, but can be unilateral. It occurs secondary to laughing, oral sex, taking a large bite, trauma,4 extraction of teeth,5*6 tonsillectomy,’ convulsions,6 dental treatment,* yawning,’ or vomiting. lo It is sustained by spasm of the muscles of mastication, particularly the lateral pterygoid and temporalis.‘1*‘2 The diagnosis of an anteriorly dislocated mandible is made by the following clinical features (Fig 1A and B): inability to close the mouth; severe pain in the region anterior to the ear; absence of the condyle from the glenoid fossa with a visible and palpable preauricular depression; inability to move the mandible except to open the mouth wider in a purely rotational manner; difficulty in speaking; a prognathic (prominent) appearing lower jaw; and, if a unilateral dislocation is present, deviation of the chin to the opposite side. The differential diagnosis consists of fractures of the mandible including fracture dislocations of the condylar neck, acute traumatic hemarthrosis, acute closed
FIGURE 1. (A) Intraoral photograph showing open bite with occlusion only on most postenor teeth. (B) Lateral facial photograph of a patient with an anteriorly dislocated mandible. Note the preauricular depression. 330
LUYK AND LARSEN W MANDIBULAR DISLOCATION
lock of the TMJ meniscus, and acute myofacial pain and dysfunction. The clinical diagnosis can be confirmed radiologically by panoramic, transcranial, transpharyngeal, or transorbital TMJ views. A panoramic view is probably the best initial screening radiograph if dislocation is suspected. The condylar head is displaced from the glenoid fossa, anterior-superior to the inferior portion of the articular eminence of the temporal bone (Fig 2). Treatment methods are designed to push the mandible inferiorly and posteriorly so as to reposition the condylar head down and around the articular eminence. There are two general methods of reduction. In the most commonly used technique (Fig 3A and B), the patient is seated in a chair with the head firmly against a wall or headrest. The level of the mandible should be at or below the height of the physician’s forearm when the elbow is flexed at 90”. The operator stands in front of the patient and his or her thumbs are placed as far posteriorly as possible on the molar teeth with the fingers curled under the angle and body of the mandible. Protective latex gloves should be worn by the operator and if the thumbs are placed directly over the molars, a towel or gauze should be wrapped around the digits to protect them when the mandible snaps closed due to muscle spasm. Alternatively, the operator’s thumbs can be positioned over the buccal aspect of mandible ridge and not be in contact with the occlusal surface of the teeth. Pressure is applied downward and backward with the thumbs to effect reduction. In the case of bilateral dislocation, it is easier to reduce one side at a time. In the second technique (Fig 4), the physician stands behind the recumbent patient, again placing the thumbs on the patient’s molar teeth and applying pressure downward and backward. Patients presenting to the emergency department
FIGURE 2. Panoramic radiograph of a patient with an anteriorly dislocated mandible. Note that the condylar head is located anterior and superior to the articular eminence (arrow) and the occlusion is only on the most posterior teeth.
with acute dislocation are in pain and often are apprehensive. Although chronic recurrent dislocation may be easy to reduce, if initial reduction is unsuccessful or the patient is overly apprehensive, sedation should be considered strongly. Intravenous diazepam to allay anxiety and reduce muscle spasm may make reduction easier.” Others advocate local anesthesia not only to provide pain relief at the site of injection but also to reduce muscle spasm. Because the lateral pterygoid is the principal muscle involved, therapy should be aimed at reducing spasm there. This objective can be achieved with a local anesthetic solution around the joint to reduce reflex spasm by decreasing pain from the joint,‘2-14 or with an injection directly into the lateral pterygoid muscle. When injection directly into the superior joint space is planned, the skin anterior to the ear is prepared. In an aseptic fashion, a 21-gauge needle is introduced into the palpable depression caused by the anterior position of the condyle (Fig 5). The needle is directed in a superior-anterior direction until contact is made with the inferior surface of the glenoid fossa. Two milliliters of 2% lidocaine is administered. If injection directly into the lateral pterygoid is planned, an intraoral approach is used. Two to 3 mL 2% lidocaine with l:lOO,OOO epinephrine is injected posteriorly to the maxillary tuberosity using a 25 gauge needle. We recommend the following treatment protocol: (1) installation of 2 mL of local anesthetic solution into the joint capsule followed by manual reduction by the anterior approach, (2) if this is unsuccessful, or the patient is overly apprehensive or the operator feels more comfortable with intravenous sedation, the careful titration of up to 20 mg intravenous diazepam followed by manual reduction; and (3) if these measures fail, general anesthesia with muscle relaxation.
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FIGURE 4. Proper positioning for reduction of an anteriorly dislocated mandible in a recumbent patient.
of 3 weeks to allow healing of the structures in and around the joint. Intermaxillary fixation is not necessary for the first-time acute anterior dislocation of the jaw. A soft diet is recommended for several days and a nonsteroidal antiinflammatory analgesic is prescribed. Chronic
Recurrent
Dislocation
Recurrent dislocation can be defined as repeated incidences of dislocation. These patients often present to the emergency department with acute dislocations if they have not been able to reduce the dislocation themselves. A careful search should be made for ini-
FIGURE 3. (A) Proper positioning for reduction of an anteriorly dislocated mandible with the patient seated. (B) Proper operator head positioning and vectors of forces (arrows) for the reduction of an anteriorly dislocated mandible.
Following successful reduction of an acute anteriorly dislocated jaw, the patient is instructed to refrain from opening the mouth widely and to support the jaw with a hand under the chin when yawning for a period 332
FIGURE 5. Lateral facial photograph showing the preauricular depression associated with an anteriorly dislocated mandible and the site of penetration and direction of advancement for the local anesthetic needle.
LUYK AND LARSEN W MANDIBULAR
tiating factors in cases of recurrent dislocation. These factors include the use of drugs which may cause extrapyramidal reactions. Acute dystonic reactions are the most likely to result in dislocation of the mandible. Neuroleptic and antiemetic medications of the phenothiazine, butyrophenone, thioxanthine, metoclopramide, and rarely tricyclic antidepressant groups may give rise to acute dystonic reactions. Management of patients on these medications will require control of the extrapyramidal reactions with diphenhydramine, benzotropine, biperiden, or trihexyphenidyl. It has recently been suggested that therapy be continued on an outpatient basis for 48 to 72 hours to prevent recurrence of the dystonic reaction. I5 Several systemic conditions may predispose a patient to acute or recurrent dislocations of the mandible. These are usually associated with ligament laxity, such as Ehlers-Danlos or Marfans syndrome. Initial management of chronic recurrent dislocations consists of manual reduction of the dislocation as for an acute dislocation. Following this, a variety of treatment alternatives have been used for prevention of recurrent dislocation. Conservative methods of treatment consist of prolonged immobilization, but relapse is frequent following the removal of fixation.’ Injection of sclerosing agents into the capsule has been suggested. 16,17 Surgical methods may be classified as restriction of the capsule and ligament,18V’9 limitation of forward movement by ligation of the condyle,20 limitation of forward movement by augmentation of the eminence,21T22 elimination of the dislocation by removal of the eminence,23-27 and prevention of dislocation by the removal of the activating muscle.28 Chronic (Prolonged) Dislocation The situation has occurred in which the patient has been unable to reach medical assistance immediately for reduction of a dislocated mandible. Hospitalization for a variety of conditions including severe psychosis,29,30 encephalitis,‘j and coma31 may prevent a patient from receiving the necessary treatment. The treating physician may be unaware of the diagnosis or be unable to achieve reduction.10,32 Lewis33 reported that in a rural population with no ready access to medical or dental treatment, dislocation of the mandible may go untreated for days or weeks. Lello34 reported similar distance problems as well as superstition as reasons for not seeking treatment. Gottlieb4 felt that reduction by conservative methods, as previously discussed, was unlikely in cases in which dislocation had been present for two months or greater. However, Hayward35 reported the successful reductions of two cases, 3 and 16 months after the onset of the original condition. Hogan and Na.ll~~~and
DISLOCATION
Fordyce’ were successful after 2.5 and 6 months, respectively. Gottlieb4 extensively reviewed the literature on the treatment for chronic dislocation. In addition to the manual techniques described earlier, he described the following techniques: (1) the wedge method, which consists of placing plugs of wood or cork in the molar region and then elevating the chin; (2) the screw method, which uses a special pair of forceps to apply pressure to separate the jaws posteriorly; and (3) a steel hook technique, in which a steel hook is used to engage the neck of the condyle and reduce the dislocation. Hogan and Nall~~~ described the use of elastic traction via arch bars applied to the maxillary and mandibular teeth. Hayward35 described a technique of wire traction at the angle of the mandible via a small incision made through the tissue below the jaw. Laskin3’ advocated myotomy of the temporalis muscle. Lewis33 described a technique in which reduction is accomplished by placing an instrument beneath the temporalis fascia and applying posterior pressure on the condylar head. Lello34 applied a technique using three bone hooks, one in each sigmoid notch and one beneath the chin. When manual and indirect techniques fail, an open reduction is indicated. Open techniques include direct open manipulation38; subcondylar osteotomies as a blind7s*39 or open procedure17,40; the inverted Lshaped ramus osteotomy”; and condylectomy,32 which is reserved for those cases in which all other methods fail to reduce the displaced condyle. POSTERIOR DISLOCATION When a blow to the mandible is received, which has a posterior vector and in rare instances does not result in fracture of the condylar neck, the condylar head may be forced in a posterior direction. There is pain in the area of the joint, limitation of opening, and laceration of the external auditory canal, often leading to hemorrhage.41,42 Cope and Lawlor42 described a case of posterior displacement with impingement on the mastoid. This patient presented with similar clinical findings to the anteriorly dislocated jaw. Treatment of posterior dislocation is by simple manipulation and management of associated ear problems. LATERAL DISLOCATION Lateral displacement falls into two subgroups43: type 1, which is the lateral subluxation, and type 2, which is complete dislocation in which the condyle is forced laterally and then superiorly into the temporal space. The diagnosis of this condition is straightforward. The condylar head is palpable as a hard mass either in the preauricular region (type 1) or in the lower part of the temporal space (type 2). This is always 333
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associated with a fracture of the mandible, usually in the body region. This condition gives rise to a marked crossbite, not attributable to a second mandibular fracture but instead to the displaced condyle. Treatment requires reduction of both the dislocation and the mandibular fracture. SUPERIOR DISLOCATION Superior dislocation into the middle cranial fossa must be associated with a fractured glenoid fossa. The medial and lateral elevated margins of the fossa normally meet the articulating surface of the condylar head on impact and protect the central weak area of the fossa. Therefore, this injury may be predisposed to when the condylar head is sma11.44Thirteen of 22 reported cases have been in females, and 11 in patients were under the age of 20 years.444 It appears that this injury is also more common when the mouth is open at the moment of impact.45 In addition, most patients suffer cerebral contusion, often facial nerve paralysis, and deafness.45 Patients with this type of injury exhibit severe restriction of oral opening, pain in the area of the TMJ, bleeding from the external auditory canal, or hemotympanum and deviation of the jaw to the affected side. A fractured mandible is not always present.4448 A variety of treatment modalities have been used, including conservative management, condylotomy, elastic traction, condylectomy, and manual reduction.44 SUMMARY Acute mandibular dislocations are a distressing condition for which patients normally seek immediate care. In most instances, a simple anterior dislocation is present. These usually can be treated adequately in the emergency department by manual reduction, local anesthesia, and possibly supplemental intravenous sedation. Other forms of dislocation are less common and require more complicated modes of therapy. REFERENCES and coronoid process. In Injuries. Edinburgh, Churchhill-Livingston, 1985, pp 337-362 Rickets RM: Variations of the TMJ as revealed by cephalometric laminography. Am J Orthod 1950;36:377-398 Wessberg GA: Mandibular condylar dislocation. Hawaii Dent J 1987;18:9-12 Gottlieb 0: Long-standing dislocation of the jaw. J Oral Surg 1952;10:25-32 Fordyce DL: Long-standing bilateral dislocation of the jaws. Br J Oral Surg 1965;2:222-225 Jones JC: On the treatment of unreduced bilateral forward dislocation of the TMJ. Br Dent J 1949;86:275-278
1. Bradley
P: Injuries
of the condylar
Rowe NL, Williams J (ads): Maxillofacial
2. 3. 4. 5. 6.
7. Wijmenga JP, Boering G, Blankestijn J: Protracted dislocation of the temporomandibular joint. Int J Oral Maxillofac Surg 1986;15:38Cf-388 334
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8. Hueston JT: The surgical exposure of the dislocated dibular condyle. Br J Plast Surg 1980;12:275-276
man-
9. Harpman JA: Treatment of old unreduced forward dislocation of the temporomandibular joints. J Oral Surg 1952;10:205-210 10. Adekeye EO, Shania RI, Cove P: Inverted L-shaped ramus osteotomy for prolonged bilateral dislocation of the temporomandibular joint. Oral Surg 1976;41:568-577 11. Watanabe Y, Otake M: Unreduced dislocation of the mandibular joint following eclampsia. Report of a surgically treated case. Oral Surg 1950;3:1010-1017 12. Poswillo D: Surgery of the temporomandibular Sci Rev 1976;6:87-118
joint.
Oral
13. Johnson WB: New method for reduction of acute dislocation of the temporomandibular joint articulations. J Oral Surg 1958;16:501-504 14. Littler BO: The role of local anesthesia in the reduction of long-standing dislocation of the temporomandibular joint. Br J Oral Surg 1980;18:81-85 15. Corre KA, Niemann JT, Bessen HA: Extended therapy for acute dystomic reactions. Ann Emerg Med 13:194-197 16. McKelvey LV: Sclerosing solution of the treatment of chronic subluxation of the temporomandibular joint. J Oral Surg 1950;8:225-228 17. Schultz LW: Report of ten years experience of treatment hypo-immobility of the TMJ. J Oral Surg 1947;5:2002-2005 18. MacFarlane WI: Recurrent dislocation of the mandible. Treatment of seven cases by a simple surgical method. Br J Oral Surg 1979;14:227-229 19. Gould JC: Shortening of the temporalis bility of the temporomandibular 1978;36:781-783
tendon for hypomojoint. J Oral Surg
20. Georgiade N: Ligation of the condyle to the zygomatic arch. Surgical correction of chronic luxation of the mandibular condyle. Plast Reconst Surg 1965;36:339-341 21. Howe AG, Kent JN, Farrell CD: Implant to the articular eminence for recurrent dislocation of the temporomandibular joint. J Oral Surg 1978;36:523-526 22. Dautrey J: Reflections poro-mandibulaire. 580
sur la chirurgie de I’articulation temActa Stomomatol Belg 1975;72:577-
23. Myrhaug H: New method of treatment for habitual dislocation of the mandible. Acta Odont Stand 1951;9:247-250 B, Frey N, McReynold 24. Saunders graphic, and clinical evaluation lar articular eminence reduction rent dislocation and chronic 1978 ;37 :34-44
J: Anatomical, radioof the temporomandibuas a treatment for recursubluxation. Ann Dent
for chronic 25. Lovely F, Copeland RA: Reduction eminoplasty recurrent luxation of the temporomandibular joint. J Can Dent Assoc 1981;47:179-184 26. Price RB: Surgical correction of recurrent dislocation of the mandibular condyle in the patient with Huntington’s chorea: The case report. Br J Oral Maxillofac Surg 1985; 23:118-122 for recurrent dislocation. 27. Progel MA: Articular eminectomy Br J Oral Maxillofac Surg 1987;25:237-243 for luxation in TMJ. Acta Chir 26. Bowman K: New operation Stand 1949;99:96-102 29. Lewis JE: Reduction of dislocation of the mandible. NY State Dent J 1961;27:29-30 joint 30. Roe PF: Correction of permanent temporomandibular dislocation. J Oral Surg 1970;28:222-228 condylar neck bisection for long31. Whiner JG: Bilateral standing dislocation of the mandibule: Report of case. J Oral Surg 1961;19:432-435
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32. Benny RA: Prolonged unilateral dislocation of the mandible. J Oral Surg 1978;38:823-624 33. Lewis JE: A simple technique for reduction of long-standing dislocation of the mandible. Br J Oral Surg 1981;18:52-56 34. Lello JE: Treatment of long standing mandibular dislocation. J Oral Maxillofac Surg 1987;45:893-896 35. Hayward JR: Prolonged dislocation of the mandible. J Oral Surg 1985;23:585-594 36. Hogan N, Nally F: Prolonged bilateral temporomandibular joint dislocation. Irish Dent Rev 1964;10:40-42 37. Laskin DM: Myotomy for the management of recurrent and protracted mandibular dislocation. Fourth International Conference on Oral Surgery, Amsterdam, 1973, pp 264268 38. Tropazian RG, Crostich ER: Management of protracted dislocation of the mandible. J Trauma 1967;7:257-264 39. Gorman JM: Condylotomy for bilateral dislocations. Br J Oral Surg 1974;12:96-98 40. Rawls HC, Bruni A, Hamilton MK: Surgical correction of the permanently dislocated jaw. Oral Surg 1973;31:385-388 41. Akers JO, Narang R, Pechamplain RW: Posterior dislocation of the mandibular condyle into the external ear canal. J Oral Maxillofac Surg 1982;40:369-370 41. Helmy M: Rare type of dislocation of the temporomandibular joint. Egypt Dent J 1977;3:27-29
42. Cope MR. Lawlor MG: An unusual mandibular dislocation. Br J Oral Maxillofac Surg 1985;23:112-117 43. lhalainen U, Tasanen A: Central dislocation or dislocation of the mandibular condyle in the middle cranial fossa: A case report and review of the literature. Int J Oral Surg 1983;12:39-45 44. Allen FJ, Young AH: Lateral displacement of the intact mandibular condyle: A report of five cases. Br J Oral Surg 1969;7:24-30 45. Musgrove BT: Dislocation of the mandibular condyle into the middle cranial fossa. Br J Oral Maxillofac Surg 1986;24:25-27 46. Pieritz U, Schnidseder R: Central dislocation of the jaw joint into the middle cranial fossa. A case report. J Maxillofac Surg 1981;9:61-63 47. Worthington P: Dislocation of the mandibular condyle into the temporal fossa. J Maxillofac Surg 1982;10:24-27 48. Copenhaver RH, Dennis MJ, Kloppedal E, et al: Fracture of the glenoid fossa and dislocation of the mandibular condyle into the middle cranidal fossa. J Oral Maxillofac Surg 1985;43:974-977 49. Awang MN: A new approach to the reduction of acute dislocation of the temporomandibular joint: A report of three cases. Br J Oral Maxillofac Surg 1987;25:244-249
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Dislocation of the temporomandibular joint (TMJ) is the displacement of the mandibular condylar head completely out of the glenoid fossa which cannot be reduced by the patient. This condition occurs relatively commonly and patients often present initially to the emergency department for treatment. The purpose of this article is to review the normal anatomy and function of the TMJ and to describe the different types of dislocations of the mandible, their clinical and radiograph diagnosis, and the initial management of the condition. The TMJ is a ginglymoarthrodial joint, implying that it combines a hinge and gliding action. It is derived embryologically from two blastomas: the temporal, which forms the glenoid fossa, and the condylar, which forms the condylar head. The articular surface of the temporal bone consists of the mandibular fossa and, anteriorly, the articular tubercle. The condyle of the mandible is rounded in an anteroposterior dimension, but resembles a narrow ellipsoid in its larger
From the “University of Otago, Dunedin, New Zealand; and the tDepartment of Oral and Maxillofacial Surgery, The Ohio State University College of Dentistry. Manuscript 1988.
received April 21, 1988; revision accepted
July 1,
Address reprint requests to Dr Luyk: Department of Oral Medicine and Oral Surgery, School of Dentistry, PO Box 847, Dunedin, New Zealand. Key Words: Mandible, mandibular joint.
jaw, dislocation,
0 1989 by W.B. Saunders Company. 07358757/89/0703-0019$5.00/O
subluxation,
temporo-
PETER E. LARSEN, DDSt
transverse dimension. The articular surfaces are covered by fibrocartilage instead of hyaline cartilage and are separated and made more congruent by an articular disk (or meniscus) composed of dense fibrous connective tissue. A portion of the lateral pterygoid muscle inserts into the anterior portion of the disk. The capsule of the TMJ is thin and loose. It is attached above to the circumference of the mandibular fossa and the articular tubercle and below to the neck of the condyle of the mandible. The capsule contains one strengthening ligament on its lateral surface. The lateral ligament is broad above where it attaches to the lower border of the zygoma and the tubercle. Its fibers are directed downward and backward to the lateral and posterior parts of the neck of the mandible. There are two accessory ligaments medially, the sphenomandibular and stylomandibular ligaments. The sphenomandibular ligament is thin and flat but very strong. It descends from the spine of the sphenoid bone to the lingula on the medial aspect of the mandible. The stylomandibular ligament is a thickening at the deep parotid fascia which extends from near the end of the styloid process to the posterior border of the ramus of the mandible near its angle. The form of the articulating surfaces is such as to facilitate a hinge action between the articular disk and the mandibular condyle in the lower cavity of the joint and a gliding action between the disk and the temporal bone in the upper cavity. The jaws are opened by forward traction on the neck of the mandible by the lower portion of the lateral pterygoid muscles, assisted by the digastric, mylohyoid, and geniohyoid muscles. The combined gliding and hinge action at this joint produces rotation of the mandible around a transverse axis which might be projected between the two lingulae. Closure of the jaws is a very powerful action produced by the combined action of the masseter, the medial pterygoid, and the temporalis muscles. The medial pterygoid muscle assists the lateral pterygoid in protrusion of the mandible. The posterior fibers of the temporalis control retrusion assisted by the suprahyoid group of muscles. Lateral excursion of the mandible is largely by the unopposed action of one of the lateral pterygoid muscles. 329
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MANDIBULAR DISLOCATION The mandibular condylar can be dislocated into a variety of positions’: anterior, posterior, lateral, and superior. Anterior dislocation occurs when the condyle moves anterior to the articular eminence. This is by far the most common situation, representing a pathologic forward extension of the normal translational movement of the condylar head. In posterior dislocation the mandibular condyle is displaced backward. It usually is associated with a coexistent fracture of the base of the skull or the anterior wall of the bony meatus of the ear. Lateral dislocation can be divided into type 1, lateral subluxation and type 2, a complete dislocation in which the condyle is forced laterally and then superiorly to enter the temporal space. Lateral dislocation requires a concomitant fracture of the body of the mandible. Superior dislocation is associated with a fracture of the glenoid fossa, with displacement of the condyle into the middle cranial fossa.
Anterior Dislocation Subluxation implies displacement that can be reduced by the patient. In as many as 70% of normal patients the condylar head routinely translates anterior to the articular eminence of the temporal bone and reduces spontaneously.* Three contributing factors interact to predispose an individual to symptomatic anterior mandibular condylar dislocation: capsular integrity, articular eminence morphology, and muscle tonicity. Capsular integrity is altered by acute or chronic mandibular hyperextension such as occurs with epileptic seizure, oroendotracheal intubation, or prolonged intraoral operative procedures. Repetitive episodes of mandibular hyperextension may induce a gradual loss of TMJ capsular integrity which permits
3 W May 1989
condylar subluxation to become progressively worse until dislocation occurs. Morphologic changes which cause a shallow eminence readily permit translation of the mandibular condyle over the articular eminence, but seldom result in traumatic dislocation. Hypertonicity of the masticatory musculature may result from phenomena such as bruxism or other parafunctional masticatory habits that induce muscle fatigue.3 Anterior dislocation of the mandible is relatively common and can be divided into three subgroups depending on how long it has been present and the frequency with which it occurs: acute, chronic recurrent, and chronic prolonged.
Acute Dislocations The majority of patients with dislocations present with an acute dislocation because of the painful nature of the condition. The condition is usually bilateral, but can be unilateral. It occurs secondary to laughing, oral sex, taking a large bite, trauma,4 extraction of teeth,5*6 tonsillectomy,’ convulsions,6 dental treatment,* yawning,’ or vomiting. lo It is sustained by spasm of the muscles of mastication, particularly the lateral pterygoid and temporalis.‘1*‘2 The diagnosis of an anteriorly dislocated mandible is made by the following clinical features (Fig 1A and B): inability to close the mouth; severe pain in the region anterior to the ear; absence of the condyle from the glenoid fossa with a visible and palpable preauricular depression; inability to move the mandible except to open the mouth wider in a purely rotational manner; difficulty in speaking; a prognathic (prominent) appearing lower jaw; and, if a unilateral dislocation is present, deviation of the chin to the opposite side. The differential diagnosis consists of fractures of the mandible including fracture dislocations of the condylar neck, acute traumatic hemarthrosis, acute closed
FIGURE 1. (A) Intraoral photograph showing open bite with occlusion only on most postenor teeth. (B) Lateral facial photograph of a patient with an anteriorly dislocated mandible. Note the preauricular depression. 330
LUYK AND LARSEN W MANDIBULAR DISLOCATION
lock of the TMJ meniscus, and acute myofacial pain and dysfunction. The clinical diagnosis can be confirmed radiologically by panoramic, transcranial, transpharyngeal, or transorbital TMJ views. A panoramic view is probably the best initial screening radiograph if dislocation is suspected. The condylar head is displaced from the glenoid fossa, anterior-superior to the inferior portion of the articular eminence of the temporal bone (Fig 2). Treatment methods are designed to push the mandible inferiorly and posteriorly so as to reposition the condylar head down and around the articular eminence. There are two general methods of reduction. In the most commonly used technique (Fig 3A and B), the patient is seated in a chair with the head firmly against a wall or headrest. The level of the mandible should be at or below the height of the physician’s forearm when the elbow is flexed at 90”. The operator stands in front of the patient and his or her thumbs are placed as far posteriorly as possible on the molar teeth with the fingers curled under the angle and body of the mandible. Protective latex gloves should be worn by the operator and if the thumbs are placed directly over the molars, a towel or gauze should be wrapped around the digits to protect them when the mandible snaps closed due to muscle spasm. Alternatively, the operator’s thumbs can be positioned over the buccal aspect of mandible ridge and not be in contact with the occlusal surface of the teeth. Pressure is applied downward and backward with the thumbs to effect reduction. In the case of bilateral dislocation, it is easier to reduce one side at a time. In the second technique (Fig 4), the physician stands behind the recumbent patient, again placing the thumbs on the patient’s molar teeth and applying pressure downward and backward. Patients presenting to the emergency department
FIGURE 2. Panoramic radiograph of a patient with an anteriorly dislocated mandible. Note that the condylar head is located anterior and superior to the articular eminence (arrow) and the occlusion is only on the most posterior teeth.
with acute dislocation are in pain and often are apprehensive. Although chronic recurrent dislocation may be easy to reduce, if initial reduction is unsuccessful or the patient is overly apprehensive, sedation should be considered strongly. Intravenous diazepam to allay anxiety and reduce muscle spasm may make reduction easier.” Others advocate local anesthesia not only to provide pain relief at the site of injection but also to reduce muscle spasm. Because the lateral pterygoid is the principal muscle involved, therapy should be aimed at reducing spasm there. This objective can be achieved with a local anesthetic solution around the joint to reduce reflex spasm by decreasing pain from the joint,‘2-14 or with an injection directly into the lateral pterygoid muscle. When injection directly into the superior joint space is planned, the skin anterior to the ear is prepared. In an aseptic fashion, a 21-gauge needle is introduced into the palpable depression caused by the anterior position of the condyle (Fig 5). The needle is directed in a superior-anterior direction until contact is made with the inferior surface of the glenoid fossa. Two milliliters of 2% lidocaine is administered. If injection directly into the lateral pterygoid is planned, an intraoral approach is used. Two to 3 mL 2% lidocaine with l:lOO,OOO epinephrine is injected posteriorly to the maxillary tuberosity using a 25 gauge needle. We recommend the following treatment protocol: (1) installation of 2 mL of local anesthetic solution into the joint capsule followed by manual reduction by the anterior approach, (2) if this is unsuccessful, or the patient is overly apprehensive or the operator feels more comfortable with intravenous sedation, the careful titration of up to 20 mg intravenous diazepam followed by manual reduction; and (3) if these measures fail, general anesthesia with muscle relaxation.
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FIGURE 4. Proper positioning for reduction of an anteriorly dislocated mandible in a recumbent patient.
of 3 weeks to allow healing of the structures in and around the joint. Intermaxillary fixation is not necessary for the first-time acute anterior dislocation of the jaw. A soft diet is recommended for several days and a nonsteroidal antiinflammatory analgesic is prescribed. Chronic
Recurrent
Dislocation
Recurrent dislocation can be defined as repeated incidences of dislocation. These patients often present to the emergency department with acute dislocations if they have not been able to reduce the dislocation themselves. A careful search should be made for ini-
FIGURE 3. (A) Proper positioning for reduction of an anteriorly dislocated mandible with the patient seated. (B) Proper operator head positioning and vectors of forces (arrows) for the reduction of an anteriorly dislocated mandible.
Following successful reduction of an acute anteriorly dislocated jaw, the patient is instructed to refrain from opening the mouth widely and to support the jaw with a hand under the chin when yawning for a period 332
FIGURE 5. Lateral facial photograph showing the preauricular depression associated with an anteriorly dislocated mandible and the site of penetration and direction of advancement for the local anesthetic needle.
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tiating factors in cases of recurrent dislocation. These factors include the use of drugs which may cause extrapyramidal reactions. Acute dystonic reactions are the most likely to result in dislocation of the mandible. Neuroleptic and antiemetic medications of the phenothiazine, butyrophenone, thioxanthine, metoclopramide, and rarely tricyclic antidepressant groups may give rise to acute dystonic reactions. Management of patients on these medications will require control of the extrapyramidal reactions with diphenhydramine, benzotropine, biperiden, or trihexyphenidyl. It has recently been suggested that therapy be continued on an outpatient basis for 48 to 72 hours to prevent recurrence of the dystonic reaction. I5 Several systemic conditions may predispose a patient to acute or recurrent dislocations of the mandible. These are usually associated with ligament laxity, such as Ehlers-Danlos or Marfans syndrome. Initial management of chronic recurrent dislocations consists of manual reduction of the dislocation as for an acute dislocation. Following this, a variety of treatment alternatives have been used for prevention of recurrent dislocation. Conservative methods of treatment consist of prolonged immobilization, but relapse is frequent following the removal of fixation.’ Injection of sclerosing agents into the capsule has been suggested. 16,17 Surgical methods may be classified as restriction of the capsule and ligament,18V’9 limitation of forward movement by ligation of the condyle,20 limitation of forward movement by augmentation of the eminence,21T22 elimination of the dislocation by removal of the eminence,23-27 and prevention of dislocation by the removal of the activating muscle.28 Chronic (Prolonged) Dislocation The situation has occurred in which the patient has been unable to reach medical assistance immediately for reduction of a dislocated mandible. Hospitalization for a variety of conditions including severe psychosis,29,30 encephalitis,‘j and coma31 may prevent a patient from receiving the necessary treatment. The treating physician may be unaware of the diagnosis or be unable to achieve reduction.10,32 Lewis33 reported that in a rural population with no ready access to medical or dental treatment, dislocation of the mandible may go untreated for days or weeks. Lello34 reported similar distance problems as well as superstition as reasons for not seeking treatment. Gottlieb4 felt that reduction by conservative methods, as previously discussed, was unlikely in cases in which dislocation had been present for two months or greater. However, Hayward35 reported the successful reductions of two cases, 3 and 16 months after the onset of the original condition. Hogan and Na.ll~~~and
DISLOCATION
Fordyce’ were successful after 2.5 and 6 months, respectively. Gottlieb4 extensively reviewed the literature on the treatment for chronic dislocation. In addition to the manual techniques described earlier, he described the following techniques: (1) the wedge method, which consists of placing plugs of wood or cork in the molar region and then elevating the chin; (2) the screw method, which uses a special pair of forceps to apply pressure to separate the jaws posteriorly; and (3) a steel hook technique, in which a steel hook is used to engage the neck of the condyle and reduce the dislocation. Hogan and Nall~~~ described the use of elastic traction via arch bars applied to the maxillary and mandibular teeth. Hayward35 described a technique of wire traction at the angle of the mandible via a small incision made through the tissue below the jaw. Laskin3’ advocated myotomy of the temporalis muscle. Lewis33 described a technique in which reduction is accomplished by placing an instrument beneath the temporalis fascia and applying posterior pressure on the condylar head. Lello34 applied a technique using three bone hooks, one in each sigmoid notch and one beneath the chin. When manual and indirect techniques fail, an open reduction is indicated. Open techniques include direct open manipulation38; subcondylar osteotomies as a blind7s*39 or open procedure17,40; the inverted Lshaped ramus osteotomy”; and condylectomy,32 which is reserved for those cases in which all other methods fail to reduce the displaced condyle. POSTERIOR DISLOCATION When a blow to the mandible is received, which has a posterior vector and in rare instances does not result in fracture of the condylar neck, the condylar head may be forced in a posterior direction. There is pain in the area of the joint, limitation of opening, and laceration of the external auditory canal, often leading to hemorrhage.41,42 Cope and Lawlor42 described a case of posterior displacement with impingement on the mastoid. This patient presented with similar clinical findings to the anteriorly dislocated jaw. Treatment of posterior dislocation is by simple manipulation and management of associated ear problems. LATERAL DISLOCATION Lateral displacement falls into two subgroups43: type 1, which is the lateral subluxation, and type 2, which is complete dislocation in which the condyle is forced laterally and then superiorly into the temporal space. The diagnosis of this condition is straightforward. The condylar head is palpable as a hard mass either in the preauricular region (type 1) or in the lower part of the temporal space (type 2). This is always 333
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associated with a fracture of the mandible, usually in the body region. This condition gives rise to a marked crossbite, not attributable to a second mandibular fracture but instead to the displaced condyle. Treatment requires reduction of both the dislocation and the mandibular fracture. SUPERIOR DISLOCATION Superior dislocation into the middle cranial fossa must be associated with a fractured glenoid fossa. The medial and lateral elevated margins of the fossa normally meet the articulating surface of the condylar head on impact and protect the central weak area of the fossa. Therefore, this injury may be predisposed to when the condylar head is sma11.44Thirteen of 22 reported cases have been in females, and 11 in patients were under the age of 20 years.444 It appears that this injury is also more common when the mouth is open at the moment of impact.45 In addition, most patients suffer cerebral contusion, often facial nerve paralysis, and deafness.45 Patients with this type of injury exhibit severe restriction of oral opening, pain in the area of the TMJ, bleeding from the external auditory canal, or hemotympanum and deviation of the jaw to the affected side. A fractured mandible is not always present.4448 A variety of treatment modalities have been used, including conservative management, condylotomy, elastic traction, condylectomy, and manual reduction.44 SUMMARY Acute mandibular dislocations are a distressing condition for which patients normally seek immediate care. In most instances, a simple anterior dislocation is present. These usually can be treated adequately in the emergency department by manual reduction, local anesthesia, and possibly supplemental intravenous sedation. Other forms of dislocation are less common and require more complicated modes of therapy. REFERENCES and coronoid process. In Injuries. Edinburgh, Churchhill-Livingston, 1985, pp 337-362 Rickets RM: Variations of the TMJ as revealed by cephalometric laminography. Am J Orthod 1950;36:377-398 Wessberg GA: Mandibular condylar dislocation. Hawaii Dent J 1987;18:9-12 Gottlieb 0: Long-standing dislocation of the jaw. J Oral Surg 1952;10:25-32 Fordyce DL: Long-standing bilateral dislocation of the jaws. Br J Oral Surg 1965;2:222-225 Jones JC: On the treatment of unreduced bilateral forward dislocation of the TMJ. Br Dent J 1949;86:275-278
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9. Harpman JA: Treatment of old unreduced forward dislocation of the temporomandibular joints. J Oral Surg 1952;10:205-210 10. Adekeye EO, Shania RI, Cove P: Inverted L-shaped ramus osteotomy for prolonged bilateral dislocation of the temporomandibular joint. Oral Surg 1976;41:568-577 11. Watanabe Y, Otake M: Unreduced dislocation of the mandibular joint following eclampsia. Report of a surgically treated case. Oral Surg 1950;3:1010-1017 12. Poswillo D: Surgery of the temporomandibular Sci Rev 1976;6:87-118
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13. Johnson WB: New method for reduction of acute dislocation of the temporomandibular joint articulations. J Oral Surg 1958;16:501-504 14. Littler BO: The role of local anesthesia in the reduction of long-standing dislocation of the temporomandibular joint. Br J Oral Surg 1980;18:81-85 15. Corre KA, Niemann JT, Bessen HA: Extended therapy for acute dystomic reactions. Ann Emerg Med 13:194-197 16. McKelvey LV: Sclerosing solution of the treatment of chronic subluxation of the temporomandibular joint. J Oral Surg 1950;8:225-228 17. Schultz LW: Report of ten years experience of treatment hypo-immobility of the TMJ. J Oral Surg 1947;5:2002-2005 18. MacFarlane WI: Recurrent dislocation of the mandible. Treatment of seven cases by a simple surgical method. Br J Oral Surg 1979;14:227-229 19. Gould JC: Shortening of the temporalis bility of the temporomandibular 1978;36:781-783
tendon for hypomojoint. J Oral Surg
20. Georgiade N: Ligation of the condyle to the zygomatic arch. Surgical correction of chronic luxation of the mandibular condyle. Plast Reconst Surg 1965;36:339-341 21. Howe AG, Kent JN, Farrell CD: Implant to the articular eminence for recurrent dislocation of the temporomandibular joint. J Oral Surg 1978;36:523-526 22. Dautrey J: Reflections poro-mandibulaire. 580
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23. Myrhaug H: New method of treatment for habitual dislocation of the mandible. Acta Odont Stand 1951;9:247-250 B, Frey N, McReynold 24. Saunders graphic, and clinical evaluation lar articular eminence reduction rent dislocation and chronic 1978 ;37 :34-44
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for chronic 25. Lovely F, Copeland RA: Reduction eminoplasty recurrent luxation of the temporomandibular joint. J Can Dent Assoc 1981;47:179-184 26. Price RB: Surgical correction of recurrent dislocation of the mandibular condyle in the patient with Huntington’s chorea: The case report. Br J Oral Maxillofac Surg 1985; 23:118-122 for recurrent dislocation. 27. Progel MA: Articular eminectomy Br J Oral Maxillofac Surg 1987;25:237-243 for luxation in TMJ. Acta Chir 26. Bowman K: New operation Stand 1949;99:96-102 29. Lewis JE: Reduction of dislocation of the mandible. NY State Dent J 1961;27:29-30 joint 30. Roe PF: Correction of permanent temporomandibular dislocation. J Oral Surg 1970;28:222-228 condylar neck bisection for long31. Whiner JG: Bilateral standing dislocation of the mandibule: Report of case. J Oral Surg 1961;19:432-435
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32. Benny RA: Prolonged unilateral dislocation of the mandible. J Oral Surg 1978;38:823-624 33. Lewis JE: A simple technique for reduction of long-standing dislocation of the mandible. Br J Oral Surg 1981;18:52-56 34. Lello JE: Treatment of long standing mandibular dislocation. J Oral Maxillofac Surg 1987;45:893-896 35. Hayward JR: Prolonged dislocation of the mandible. J Oral Surg 1985;23:585-594 36. Hogan N, Nally F: Prolonged bilateral temporomandibular joint dislocation. Irish Dent Rev 1964;10:40-42 37. Laskin DM: Myotomy for the management of recurrent and protracted mandibular dislocation. Fourth International Conference on Oral Surgery, Amsterdam, 1973, pp 264268 38. Tropazian RG, Crostich ER: Management of protracted dislocation of the mandible. J Trauma 1967;7:257-264 39. Gorman JM: Condylotomy for bilateral dislocations. Br J Oral Surg 1974;12:96-98 40. Rawls HC, Bruni A, Hamilton MK: Surgical correction of the permanently dislocated jaw. Oral Surg 1973;31:385-388 41. Akers JO, Narang R, Pechamplain RW: Posterior dislocation of the mandibular condyle into the external ear canal. J Oral Maxillofac Surg 1982;40:369-370 41. Helmy M: Rare type of dislocation of the temporomandibular joint. Egypt Dent J 1977;3:27-29
42. Cope MR. Lawlor MG: An unusual mandibular dislocation. Br J Oral Maxillofac Surg 1985;23:112-117 43. lhalainen U, Tasanen A: Central dislocation or dislocation of the mandibular condyle in the middle cranial fossa: A case report and review of the literature. Int J Oral Surg 1983;12:39-45 44. Allen FJ, Young AH: Lateral displacement of the intact mandibular condyle: A report of five cases. Br J Oral Surg 1969;7:24-30 45. Musgrove BT: Dislocation of the mandibular condyle into the middle cranial fossa. Br J Oral Maxillofac Surg 1986;24:25-27 46. Pieritz U, Schnidseder R: Central dislocation of the jaw joint into the middle cranial fossa. A case report. J Maxillofac Surg 1981;9:61-63 47. Worthington P: Dislocation of the mandibular condyle into the temporal fossa. J Maxillofac Surg 1982;10:24-27 48. Copenhaver RH, Dennis MJ, Kloppedal E, et al: Fracture of the glenoid fossa and dislocation of the mandibular condyle into the middle cranidal fossa. J Oral Maxillofac Surg 1985;43:974-977 49. Awang MN: A new approach to the reduction of acute dislocation of the temporomandibular joint: A report of three cases. Br J Oral Maxillofac Surg 1987;25:244-249
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