Abstract
Dislocation of the temporomandibular joint occurs when the mandibular condyle is displaced anteriorly beyond the articular eminence and represents 3% of all dislocated joints reported in the body. Superolateral dislocation of the condyle into the temporal fossa is well documented in the literature, but anterosuperior dislocation without an associated fracture is rarely described. This report documents the case of a middle-aged woman with bilateral anterosuperior dislocation of the intact mandibular condyle after a fall on the face. This report reviews the literature on dislocations, suggests a nomenclature, possible causative mechanism and documents the importance of early management.
Dislocation of the temporomandibular joint (TMJ) occurs when the mandibular condyle is displaced anteriorly beyond the articular eminence with complete separation of the articular surfaces and fixation in that point, and represents 3% of all dislocated joints reported in the body . A more apt description, terms it as a clinical condition ‘when the condyle head is displaced out of the glenoid fossa but still remains within the capsule of the joint’ . When the trauma is severe and the displacement correspondingly great, disruption of the capsule may result in the condylar head lying outside the confines of the capsule . In contrast, subluxation is attributed to weakness and laxity of the capsule, it represents a condition in which the condylar head moves anterior to the eminence on wide opening, while the mouth can be closed again easily. Complete dislocation of the mandibular condyle can be anterior, posterior, superior or lateral . Anterosuperior dislocation is rare with only one unilateral case (4%) reported in literature . Superolateral dislocation of the condyle, though uncommon, has been reported in 19 cases. A llen and Y oung , first reported five cases, and divided them into two types: type I (lateral subluxation), in which the condyle is laterally dislocated out of the fossa; and type II (complete dislocation), in which the condyle passes laterally and then superiorly to enter the temporal fossa. S atoh et al. reported 1 case and further classified type II dislocation into type IIA, in which the condyle is not hooked above the zygomatic arch; type IIB, in which the condyle is hooked above the zygomatic arch; and type IIC, in which the condyle is lodged inside the zygomatic arch, which is fractured.
The authors report a case of bilateral anterosuperior dislocation of the intact condyles into the temporal fossa without a concomitant fracture of the mandible. This report reviews the literature on dislocations, suggests a nomenclature and a possible causative mechanism, and documents the importance of early clinical management.
Case report
A 47-year-old woman presented, complaining of an inability to close her mouth, chew food and speak properly. She gave a history of a fall on the chin from a three-wheeler public transport vehicle, 45 days previously, following which she lost consciousness for a few minutes. She was admitted to a rural government hospital where she was kept under observation to rule out a head injury or associated neurological symptoms, and for the management of facial and mandibular injuries. After discharge she was kept on a liquid diet. Her complaints persisted and she was referred to the authors.
Physical examination showed an anterior open bite without deviation of the mandible ( Fig. 1 ), with hollowness in the preauricular regions on both sides. No facial nerve deficit was noted. The maxillary arch was constricted with a high arched palate and the lower incisor teeth were crowded and supra erupted. There was generalized attrition of the dentition. Routine radiological examination (orthopantomography and lateral oblique views) revealed anterosuperior displacement of the intact left and right condyles in the temporal fossa with no fracture of the mandible ( Fig. 2 ).
A provisional diagnosis of bilateral TMJ dislocation was made and manual reduction was planned under general anesthesia. This was unsuccessful. The joints were opened with the standard Al-Kayat and Bramley approach. Both the intact condyles were dislocated out of their respective glenoid fossae and were stuck between the zygomatic arch and the temporal fossa after tearing the capsule and the ligaments ( Fig. 3 ). There was no fracture of the zygomatic arch on either side. The right coronoid process was stuck between the anterolateral wall of the maxilla and the antero-inferior surface of the zygoma. The left and right articular eminences were steep and the glenoid fossae deep. On the left side, eminectomy and high condylar shave was performed and on the right side condylectomy with coronoidectomy was carried out. Following adequate reduction, capsular and soft tissue repair was done to the extent possible. The patient was placed into maxillo-mandibular fixation (MMF) for 3 weeks, to allow adequate healing, followed by active physiotherapy for the next 6 months.
She was followed up for 9 months and at that time could maintain a mouth opening of 33 mm with adequate mandibular function and a satisfactory occlusion ( Fig. 4 ).
Discussion
There is a general consensus that fracture of the relatively slender condylar neck serves as a safety mechanism so that superior and posterior dislocations of the condylar head are often avoided . In the present case, the cause of the dislocation was a high impact injury caused by a fall from a moving vehicle. It is postulated that during this fall, the passenger was frightened and suddenly opened her jaw either to scream or from fright, with the chin hitting the metalled road. The force of the impact displaced the condyles anterior to the articular eminence, rupturing the capsular and ligamentous attachments to the condylar head, and drove the condyles upwards anterior to the eminence, medial to the zygomatic arches and lateral to the temporalis muscle and fascia into the temporal fossa. The magnitude of the impact and displacement could be gauged by the fact that the right coronoid process was stuck between the maxilla and the body of the zygoma.
W orthington suggested a mechanism for such a dislocation, stating that two obstacles need to be overcome to achieve such a condition. First, the necessary rupture of the soft tissue attachments around the condyle. Second, the transverse dimension of the condylar head (from lateral pole to medial pole) exceeds the lateral dimensions of the space between the zygomatic arch and the medial bony well of temporal fossa. In order for the condylar head to pass this obstacle, it is necessary for at least one of following three things to happen: the zygomatic arch may fracture, affording more room for the condyle to pass; the condylar head may fracture, decreasing the bulk; the condyle head may rotate about a vertical axis, which would be likely to occur only in association with a mandibular fracture disposed to facilitate rotation of the ramus.
To overcome the second obstacle, it is mandatory for one of the fractures to occur. A llen and Y oung , S atoh et al. and K apila and L ata , support this and emphasize that a fracture of the symphysis and/or body of the mandible is a prerequisite for the lateral dislocation of the mandibular condyle. B u et al. reported a case of superolateral dislocation of the intact mandibular condyle into the temporal fossa with no associated fractures, thus negating all the previous theories. They assumed it to be due to a round condyle and elastic zygomatic arch in their patient. In the present case, neither the mandible nor the zygomatic arches were fractured.
No previous reports on condyle dislocations have commented on the basic occlusal/skeletal classification of the patient (i.e. Class I, II or III). Studies on the morphology of the condyle suggest that Class II patients with a deep bite, similar to the present patient, tend to have a condyle to fossa relationship in which the condyles are placed more anterior in the fossa that is more beneath the articular eminence. Owing to the loading pattern in such cases, the shape of the condyles tend to be more round than oval. M yrhaug related the bony architecture to dislocation. He observed that a deep overbite was frequently associated with a deep glenoid fossa and a steep articular eminence, which he surmised to be conducive to dislocation. The authors consider that this could be a major predisposing factor of the intact dislocation seen in the present case.
Another factor reviewed was the time between injury and reduction ( Table 1 ). It ranged from 1 to 16 days. In the present case, the patient presented 45 days after injury. After a certain lapse of time, closed reduction methods usually fail due to fibrosis of the soft tissues. This led to an open reduction in the present case, which was difficult to perform.
| Years | Authors | Type | Unilateral or bilateral | Reduction time (days) | Reduction | Outcome |
|---|---|---|---|---|---|---|
| 1969 | A llen and Y oung | I | U | 8 | Partial (C) | Fibro-osseous Ankylosis |
| II | U | 15 | Nil (C) | Gross malocclusion | ||
| I | B | 1 | Complete (C) | 25% reduction | ||
| I | U | 1 | Complete (C) | Full range of jaw movement | ||
| II | U | 1 | Complete (C) | Not Available | ||
| 1978 | B rusati and P aini | II | U | 1 | Complete (C) | With Facial Palsy, not detailed |
| II | U | 12 | Complete (O) | With Facial Palsy and full jaw function | ||
| 1982 | W orthington | Unusual | U | 14 | Partial (O) | Fibro-osseous Ankylosis |
| 1988 | D eVita et al. | II | B | NA | Complete (O) | Not Available |
| 1989 | F erguson et al. | II | U | 1 | Complete (O) | Condylectomy, arthroplasty by costal cartilage, 30 mm mouth opening |
| 1989 | T o | II | U | 14 | Complete (O) | Bifid Condyle, reduced mouth opening |
| 1994 | S atoh et al. | II | B | 13 | Partial (O) | Condylectomy, 30 mm mouth opening |
| 1996 | K apila and L ata | II | U | 7 | Complete (O) | 30 mm mouth opening |
| 1998 | H oard et al. | II | B | NA | Complete (C) | Not Available |
| 2000 | Y oshii et al. | II | B | 16 | Complete (C) | 20 mm mouth opening |
| 2002 | R attan | II | U | 14 | Complete (O) | 30 mm mouth opening |
| II | B | NA | Not Reduced | Interpositional Gap Arthroplasty | ||
| 2007 | H sieh et al. | II | B | 1 | Complete (C) | 41 mm mouth opening |
| 2007 | B u et al. | II | U | 5 | Complete (C) | 37 mm mouth opening |
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