Case report

A 16-year-old male was involved in a motor vehicle accident and reported that he hit his chin against the steering wheel. He was brought to hospital by ambulance complaining that he was unable to close his mouth. The patient was fully awake and clinically presented with fullness over the right preauricular area, a contusion on his chin and an open bite with deviation to the right ( Fig. 1 ). Computed tomography (CT) revealed a non-displaced right zygomatic arch fracture, dislocation of the right condyle displaced outside the glenoid fossa, superiorly and laterally into the temporal fossa ( Fig. 2 ). The left condyle was displaced anterior to the articular eminence. Neither condyle was fractured. Attempts to reduce the dislocation under local anaesthesia and parenteral sedation were unsuccessful. The Oral and Maxillofacial Surgery Service at Indiana University was consulted. The patient was taken to the operating room on the day of admission for reduction of the bilateral condylar dislocation. Under general anaesthesia via nasotracheal intubation, with the patient completely paralyzed, multiple attempts to bimanually reduce the dislocation by applying downward pressure were unsuccessful. An incision was then made in the posterior right buccal vestibule of the mandible to gain access to the right ramus and coronoid process. A right coronoidectomy was performed to free some of the tendinous attachments of the temporalis muscle. A Seldin elevator was placed lateral to the right ramus where downward and medial pressure was applied to reduce the dislocation. This was confirmed by the occlusion and postoperative CT ( Fig. 3 ). The patient was placed in intermaxillary fixation (IMF) utilizing Erich arch bars and a combination of 24 and 26 gauge wires, for 2 weeks. After 2 weeks the IMF was removed and the occlusion was intact and reproducible; however, mouth opening (<5 mm) and range of motion were very restricted. The patient began mouth-opening exercises utilizing tongue blades. He was instructed to fit as many tongue blades as possible between his maxillary and mandibular posterior teeth and to crank his mouth open firmly several times daily. Each day he was asked to try to add an additional tongue blade to the existing stack of blades to increase his mouth opening. Six weeks after the traumatic injury his maximum incisal opening was approximately 32 mm, with lateral excursions approximately 5 mm bilaterally ( Fig. 4 ).

Patient presentation on admission. Note open mouth due to dislocation.

CT showing superolateral dislocation of right condyle.

Post-reduction CT showing condyles within fossa.

Patient 6 weeks after reduction with gradually improving mouth opening.

Discussion

Superolateral dislocation of the condyle occurs very infrequently. Allen & Young first reported lateral displacement of the condyle and classified the dislocation into type I (lateral subluxation), where the condyle is laterally displaced out of the glenoid fossa, and type II (complete dislocation) where the condyle is displaced laterally as well as superiorly entering the temporal fossa. Satoh et al. further subdivided 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 present case would be considered a type IIC fracture. In some literature, it has been suggested that for a type II dislocation to occur, a mandible fracture in the area of the symphysis or body is a requirement . Recently, this has been shown not to be true , as in the present case. For bilateral superolateral dislocation of intact condyles to occur, a fracture of the mandible must occur to allow for the increase in gonial width.

Management of these dislocations depends on the presence of fractures, in particular those of the mandible. If fractures are present in addition to the dislocation they have to be addressed via closed or open techniques, with or without rigid fixation. The first choice for management of a dislocation should be a manual or closed reduction because it is safe, simple and the least traumatic , even if a few days old . Owing to the difficulty of the procedure and patient comfort, this is best done under general anaesthesia. Attempts to reduce manually by grasping each side of the mandible by placing one’s thumbs over the posterior teeth and remaining fingers on the inferior border of the mandible may be tried first. Failure to reduce the dislocation means alternatives have to be considered. Some have suggested using strong traction via a wire through the mandibular angle placed extraorally . Others have used a forceps mouth gag successfully , which may have been an option in the present case, but was not considered. All these techniques may work for type I, IIA and possibly IIC dislocations, however type IIB may require an open reduction to ‘unhook’ the condyle from the zygomatic arch . Dislocations that have been delayed may require an open reduction because of the development of scarring and fibrosis. Immediate or early reduction is advised when feasible. In the present case, the idea of placing a wire through the mandibular angle was considered, however the authors think that their method is preferable because an extraoral scar is avoided as is possible injury to the marginal mandibular branch of the facial nerve. A postoperative course of intermaxillary fixation was applied to stabilize the reduction. This was followed by aggressive physiotherapy to increase the mandibular range of motion gradually.

In summary, superolateral dislocation of the mandibular condyle is rare and can be overlooked by the inexperienced clinician. It can be diagnosed with a thorough clinical and radiographic examination. Based on the literature, reduction should be attempted as soon as the diagnosis is made. This should be followed by a short period of intermaxillary fixation (about 2 weeks) and physiotherapy to improve mandibular range of motion.