Introduction

Temporomandibular joint (TMJ) ankylosis is a challenging condition leading to the fusion of the mandibular condyle with the base of the skull, and causes distressing conditions including impaired speech, difficulty in chewing, facial disfigurement, and compromise of the airway, aesthetics, and function, as well as psychological stress. The ultimate goal of managing such patients should be to establish movement and function in the jaw, prevent relapse, restore appearance, and achieve normal growth and occlusion in the child.

The treatment of TMJ ankylosis poses a significant challenge because of technical difficulties and a high incidence of recurrence. A complex and distorted anatomy with loss of anatomical landmarks also makes this type of surgery particularly difficult, carrying significant risk of injury to vessels, nerves, and the middle cranial fossa. Complicated reconstruction is needed for the total resection of the joint to provide rehabilitation of mandibular movement, restore mandibular ramus height, improve the occlusal plane, and, in the case of children, allow further mandibular growth.

The development of ankylosis is a gradual process of bony changes in the joint. So when considering the treatment for ankylosis, the stage of disease at the time of presentation should be kept in mind. In 1986, Sawhney was the first to classify TMJ ankylosis, dividing it into four types (types I–IV) on the basis of anatomical relationships as shown on computed tomography (CT) of the joint. The more common among these are type III and type IV ankylosis. Type III ankylosis involves an improperly treated or displaced condylar process fracture; in this condition a clear bridge of bone is present between the ramus and zygomatic arch, and after the bony bridge is excised, the upper articular surface and the articular disc on the deeper surface are intact. Also, a condyle of reduced size and slightly medial to its normal anatomical position exists and is potentially functional. In type IV, there is complete bony fusion of the condyle, glenoid fossa, zygomatic arch, and sigmoid notch.

Along with a panoramic view, CT is important for determining the type of ankylosis, in particular the coronal CT view of the TMJ, which gives the best identification of type III ankylosis.

Zhi et al. reported that the commonly accepted surgical approach for the treatment of ankylosis types III and IV includes total resection of the ankylotic area with special attention to the medial aspect of the joint remnants. However, Nitzan et al. first hypothesized that while managing type III cases, the integrity and location of the displaced condyle can be determined and that both the condyle and disc should be preserved rather than eliminated; they should fulfil their assigned roles in mandibular function and growth, even with their awkward shape and medial position. This treatment objective can be achieved by selective lateral arthroplasty of the affected TMJ, by simply removing the lateral bony chunk and allowing the remaining mandibular condyle and disc to function in articulation with the glenoid fossa.

The present study evaluated the feasibility of the lateral TMJ arthroplasty as an effective treatment choice for Sawhney’s type III cases of TMJ ankylosis in 15 patients.

Patients and methods

A retrospective study was performed of 15 patients with TMJ ankylosis (13 unilateral and 2 bilateral; 17 joints) who attended an oral and maxillofacial surgery outpatient department between 2007 and 2011. This retrospective chart review was exempted from institutional review board approval. Information on age, gender, mode of onset, duration, and maximum inter-incisal mouth opening (MIO) ( Fig. 1 ) was recorded. Panoramic radiography and CT examinations were done, and the type of ankylosis was determined in coronal view using Sawhney’s classification ( Fig. 2 ). Type III ankylosis patients were included in the study; patients with a history of previous TMJ surgery were excluded. The MIO was measured (the distance between the incisors) using a Vernier calliper device. Protrusive movements were measured as the total mandibular incisal protrusion plus overjet in the at-rest position; laterotrusive movements were measured in respect to the maxillary mid-line. A visual analogue scale was used to assess postoperative pain, with a value of 0 indicating no pain and a value of 10 indicating severe pain. All patients underwent routine haematological examinations. All surgical procedures were carried out under general anaesthesia by nasotracheal intubation using nasal endoscopy. The protocol presented was aimed at attaining the goal of a well-functioning, short condyle in a medial location after the resection of the lateral bony ankylotic mass.

Preoperative photograph of the patient showing restricted mouth opening.

Preoperative CT of the patient.

Patients and methods

A retrospective study was performed of 15 patients with TMJ ankylosis (13 unilateral and 2 bilateral; 17 joints) who attended an oral and maxillofacial surgery outpatient department between 2007 and 2011. This retrospective chart review was exempted from institutional review board approval. Information on age, gender, mode of onset, duration, and maximum inter-incisal mouth opening (MIO) ( Fig. 1 ) was recorded. Panoramic radiography and CT examinations were done, and the type of ankylosis was determined in coronal view using Sawhney’s classification ( Fig. 2 ). Type III ankylosis patients were included in the study; patients with a history of previous TMJ surgery were excluded. The MIO was measured (the distance between the incisors) using a Vernier calliper device. Protrusive movements were measured as the total mandibular incisal protrusion plus overjet in the at-rest position; laterotrusive movements were measured in respect to the maxillary mid-line. A visual analogue scale was used to assess postoperative pain, with a value of 0 indicating no pain and a value of 10 indicating severe pain. All patients underwent routine haematological examinations. All surgical procedures were carried out under general anaesthesia by nasotracheal intubation using nasal endoscopy. The protocol presented was aimed at attaining the goal of a well-functioning, short condyle in a medial location after the resection of the lateral bony ankylotic mass.

Preoperative photograph of the patient showing restricted mouth opening.

Preoperative CT of the patient.

Surgical protocol

The following surgical protocol was followed: (1) the CT coronal section was used to plan the incision between the ankylotic site and the displaced condyle, taking into consideration that the displaced condyle and disc are hidden medially and that a small error in the angle of the osteotomy can cut through the condyle ( Fig. 3 ). (2) The bony ankylotic mass was resected on the lateral aspect leaving about 1.5–2 cm distance from the base of the skull to the neck of condyle. (3) The condyle was left untouched ( Fig. 4 ). (4) A coronoidectomy was performed on the affected side using the same approach. (5) If steps 2 and 4 did not result in maximum mouth opening greater than 35 mm, a coronoidectomy was performed on the contralateral side using an intraoral approach. (6) The native disc was sutured (to cover the condyle) to the capsule. If adequate disc tissue was not available to cover the condyle, then the condyle was separated from the fossa by an interpositional material. This was done using a temporalis myofascial flap.

Line diagram showing preoperative image of type III ankylosis.

Intraoperative photograph showing residual disc and rudimentary condyle after removal of the lateral bony mass.

Physiotherapy was started from the first postoperative day, which consisted of active and passive exercises: active hinge opening and excursive movements combined with manual finger stretching in front of a mirror. The exercises were performed for 2 days, 4 times daily for 5 min by clock. At 3 days postoperatively, mouth opening exercises with a mouth prop were started, 4–5 times daily for 3–5 min. A mouth gag was applied after 1 week to improve mouth opening and then physiotherapy was continued at home with spoon spatulas.