Traumatic Posterior Dislocation of Bilateral Mandible Condyles into External Auditory Canal Treated with Midline Mandibulotomy: A Rare Case Report and Review of Literature

Abstract

Background

Posterior dislocation of the condyle from the glenoid fossa fracturing the anterior wall of the canal and ultimately restricting lower jaw movements is a rare condition. It may occur due to lax intra-articular ligaments or periarticular tissue or as a result of injury to the chin region. Very few cases of this condition are reported in the literature.

Purpose

The purpose of this article is to present a rare case report and review of literature related to posterior dislocation of bilateral mandible condyles to the external auditory canal, its diagnosis, and treatment with midline mandibulotomy.

Method

We used conservation methods to reduce it initially but not succeeded. Then we used midline mandibulectomy to reduce the individual condyle to its original position without opening the condyle region.

Results

We achieved a successful reduction of the dislocation and achieved with good occlusion and postoperative mouth opening. No complications like recurrence and TMJ ankylosis occurred.

Conclusion

Bilateral posterior dislocation is a rare condition; proper clinical, radiographic diagnosis, and early treatment with manual or surgical intervention are required to avoid complications.

Introduction

A common site for mandibular condyle dislocation is anterior, medial, and lateral, but the posterior dislocation is extremely rare [1–3]. Trauma to the chin generally causes direct or indirect injuries to various parts of the mandible [4]. Most of the indirect injury impact causes condylar neck and subcondylar fractures. If the condyle does not fracture or not laterally dislocated, the posterior force vector causes dislocation of the condyle in the backward direction led to the fracture of the external auditory canal (EAC) [5]. A very few cases have been reported in the English literature related to posterior dislocation of mandibular condyles till date. So the treatment of posterior dislocation of condyle has not been described in the literature due to its rare occurrence and individual approach to treat by each surgeon. We report a rare case of posterior dislocation of bilateral mandible condyles into the external auditory canal in a male patient, which was treated with a midline mandibulotomy after the failure of all the conservative methods.

Case Report

A 25-year-old male victim of trauma over chin reported to us with a chief complaint of inability to open mouth and pain in the preauricular region. The physical examination revealed a definite facial asymmetry, with a severely retruded chin, increased overbite up to 10 mm, and a lack of lateral and protrusive mandibular movement on excursions. A deep wound over the chin was present. Pain on palpation was present in both the preauricular regions. The patient was unable to close his mouth, and saliva was drooling from the mouth. Computed tomography of the face was done and showed no fracture of the mandible. In the joint region, both the condyles were posteriorly dislocation outside from its functional position fracturing external auditory canal. Both condyles were dislocated into the external auditory canal with an intact tympanic membrane without any evidence of cerebrospinal fluid leakage. Manual reduction with conservative anterior traction under local anesthesia was first tried but failed to reduce, which was followed by the reduction of condyles under general anesthesia was also attempted, but all attempts proved to be futile. Then midline mandibulotomy was planned to reduce the individual condyles into the original position as per our institute protocol for the treatment of chronic dislocations. The anterior mandible was exposed through existed lacerations, and bone plates were adapted before osteotomy to achieve exact anatomical fixation after surgery. Stepped midline mandibulotomy was performed to reduce the condyles in an anterior position and restore the occlusion. Bleeding from the left ear was observed at the time of manipulation. Maxillomandibular fixation was done to avoid the recurrence.

Postoperatively, antibiotics, and analgesic for five days, along with indomethacin 75 mg twice daily for 15 days was prescribed to prevent idiopathic bone formation. Maxillomandibular fixation was released after one week, and guiding elastics were placed for 4 weeks. Postoperative cone-beam computer tomography revealed the reduction of both condyles into its original position in glenoid fossa from EAC. After surgery, he was attached to the otolaryngology clinic for reduced hearing from the left ear and recovered from it within a month. Satisfactory occlusion with a mouth opening of 35 mm was seen after 4 months follow-up. The left lower lateral incisor showed grade III mobility when the arch bar was removed, and it was extracted. The patient refused to replace his extracted tooth. No recurrence of dislocation or ankylosis was observed on a follow-up, and we are doing continue to follow-up of the patient.

Discussion

Bilateral posterior dislocation of the condyles into EAC is extremely rare [5–7]. Only two cases are reported in the English literature. An anterior open bite, increased overjet, restricted jaw movements, empty glenoid fossa, bleeding from the ear, and no palpable condylar movements are the main clinical findings of posterior dislocation of condyles as in our case also [5, 6]. Imaging modalities like CT, CBCT, and magnetic resonance imaging are must rule out cases of displacement of the condyle in a posterior direction to posterior tubercle of the glenoid fossa, fracture of the bony walls of EAC and displacement of condyle into middle cranial fossa [4, 7]. Akers et al., in his first single case report, stated that for posterior dislocation, few anatomical features such as just below posterior articular ridge a triangular area short of bone and this lateral part further is not supported by enough bone posteriorly. The medial aspect of the glenoid fossa has a thin bone, which causes posterior displacement, and fractures anterior wall of EAC are some critical factors. Another consideration regarding the thickness of superficial soft tissue, which is incompletely covered by the cartilage allows posterior dislocation might be responsible for it [5]. According to their findings, they observed that due to over closure of edentulous jaws, it causes posterior deflection of anterior forces directed toward the area devoid of bone that ruptures the EAC. Li et al. considered a few factors such as size and direction of force, the position of the jaw during force and anatomical feature of the joint area might be the reasons for such dislocations [8]. Seymour and Musgrove, in their articles, described the relationship of the open mouth at the time of impact and supero-posterior force cause displacement of the condyle to middle cranial fossa [2, 3]. Antoniades et al. also described a case of posterior dislocation of condyles into EAC. According to them, bleeding from the ear may be the first sign of posterior dislocation, and fracture of EAC, hearing loss, and facial nerve weakness can be the associated features of posterior dislocation [6]. Vasconcelos et al., in a  case of a unilateral posterior dislocation, concluded that CT imaging should be considered as the gold standard to differentiate it from lateral dislocation or subcondyle fractures. Closed reduction should be the first preferred method to treat it with otolaryngologist consultations to rule out tympanic and EAC injuries [7].

Vishwas et al., in his first case of bilateral posterior dislocation of mandible condyle, reported difficulty in mouth opening, bilateral severe ear pain, bleeding, loss of hearing, and occlusion of both EAC. They treated it with downward and forward pull with kocher, s forceps at the angle after its exposure by submandibular incision. The hearing was improved on follow-up with normal occlusion [8]. Early intervention with manual reduction and traction with elastics are recommended under local anesthesia by many authors. If these failed, reduction with angle pulls wire, sigmoid notch hook, and more surgical procedures like midline mandibulotomy, direct exposure of condyle and condylectomies under general anesthesia are other methods reported in the literature [9, 10]. As trauma is the most common cause of posterior dislocation, subsequent hemorrhage can cause fibrosis, making it difficult to translate the condyle in its original position [10]. In this case, the author preferred midline mandibulotomy as it is an indirect technique that avoids the direct exposure of TMJ, easily controlled, and was a time-saving procedure. Bleeding from the ear, hearing loss, stenosis, infection, and TMJ ankylosis can be avoided with regular follow-up; proper care, early immobilization of jaws, and consultations of otolaryngologist are must to avoid complications related to EAC injury and hearing loss.

Conclusion

Posterior dislocation of bilateral mandible condyles without other site fractures is extremely rare, as this is the second case reported in the English literature. Clinical features and diagnostic imaging are most important for the diagnosis of these cases. Due to its rarity, no specific treatment algorithm is present in the literature. It depends upon the surgeon's experience. The authors recommend proper diagnosis with imaging techniques and early intervention with manual reduction or surgical procedures like midline indirect mandibulotomy to reduce it and to avoids unwanted complications such as hearing loss, stenosis, and ankylosis of the temporomandibular joint.

Fig. 1.

a Showing posteriorly forced mandible. b Axial CT scan showing posteriorly dislocated bilateral condyles and fracture of EAC (black arrows). c Anterior traction with heavy elastics

Fig. 2.

a Midline stepped mandibulotomy from extraoral laceration. b Fragments reduced, and occlusion achieved done. C1,2 Postoperative view of CBCT showing reduction of the condyle to fossa (black arrows)and slight flaring. D1,2 Postoperative occlusion and mouth opening after four months of follow-up

Table 1.

Published case of posterior dislocation of mandible condyle in English literature till date

Author/year	Age/gender/side	Clinical features	Radiological features	Treatment method	Outcome/complications
Aker et al. (1982)	46/M. left	Immobilization of TMJ, reduced mouth opening	Posterior dislocation of the condylar process to EAC	Manual reduction under local anesthesia	31 mm mouth opening, partial stenosis of EAC
Antoniades (1992)	49/M/right	Facial nerve palsy, restricted mandible movements	Posterior dislocation of the condyle, fracture right tympanic plate, occlusion of EAC	No treatment	Facial nerve palsy, hearing loss pneumonia,
Vasconcelos et al. (2010)	30/M/left	Chin deviated toward the left side, anterior open bite, unable to occlude, lack of mandible excursion	No fracture of mandible, condyle posteriorly displaced	Percutaneous traction with a zygomatic hook under GA	Bleeding from the canal after reduction
Vishwas et al. (2017)	80/M bilateral	Reduced mouth opening, loss of hearing, ear pain with occasional ear bleeding	Condylar dislocation posteriorly, occlusion of bilateralism, condylar fracture	Reduction Kocher’s forceps within a downward and forward direction	Hearing loss gradually improved with time
Abilia et al. (2017)	80/F/left	Conductive hearing loss, purulent discharge from EAC, trismus, limited movement deviation of chin	Posterior condyle dislocation, with violation of EAC	open arthroplasty and use of reverse double mini Mitek technique to prevent recurrent dislocation	Hearing loss
Present case (2019)	25/M/bilateral	Increased overjet, inability to open and close mouth, bleeding from the ear	Posteriorly displaced condyle. Fracture of anterior wall of EAC	Reduction with midline mandibulotomy after the failure of conservative methods	Hearing loss and tinnitus

Funding

No any financial support.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.