Temporomandibular joint ankylosis (TMJA) involves heterotopic ossification in the joint space between the mandibular condyle and glenoid fossa, leading to restricted mandibular mobility. This end-stage TMJ disease impairs mandibular growth and function, reducing quality of life. The most common etiology is trauma (79%–90%), followed by infection spreading from middle ear, inflammatory arthritis of TMJ, late degenerative joint disease (DJD) and unexplained causes, among others. ^,

In unilateral TMJA , the shortened ramus and mandibular body manifest as facial asymmetry, chin deviation, occlusal cant, and reduced posterior airway space. The severity depends on age of onset and duration of ankylosis. Long standing bilateral involvement would cause severe retrognathia. Restricted contralateral laterotrusion results from bony fusion and atrophy of the ipsilateral lateral pterygoid muscle ( Fig. 1 A-D ).

( A ) Preoperative frontal photograph of a 10 years old male with deviated chin and facial asymmetry due to left TMJA. ( B ) Preoperative frontal photograph of a pediatric female patient with mandibular retrognathia due to bilateral TMJA. ( C ) Preoperative profile photograph of the patient in Fig. 1 B showing mandibular retrognathia. ( D ) Profile photograph of the same patient showing mouth opening and progressive mandibular retrognathia at 10 years follow-up after gap arthroplasty.

Imaging modalities of choice are computed tomography (CT; cone-beam or noncontrast, 0.6–1 mm slice thickness, zero-degree gantry tilt) and orthopantomogram (OPG). Consider CT angiogram in recurrent cases with large ankylotic mass to assess proximity/entrapment of the maxillary artery (risk of hemorrhage; may require preoperative embolization or intraoperative external carotid ligation).

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  Evaluate glenoid fossa integrity and temporal bone pneumatization.

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  Detailed structured reporting aids surgical planning.

Additional radiographic features include enlarged ipsilateral coronoid process and deepened antegonial notch due to unopposed activity of ipsilateral temporalis, masseter, and medial pterygoid muscles.

Anesthetic Considerations : Reduced mouth opening and associated severe facial deformity poses an anesthetic challenge. Preferred technique is flexible fibreoptic bronchoscopy guided nasotracheal intubation in spontaneously breathing patients (awake or sedated). Topical airway anesthesia via nebulization, nerve blocks, or spray-as-you-go. Extend safe apnoea time with apnoeic oxygenation (nasal cannula or nasopharyngeal airway); advanced options include high-flow nasal oxygenation or THRIVE.

Ankylosis should be released as soon as it is diagnosed. The mainstay of management is radical release of ankylosis (1–1.5 cm gap), and ramus condyle unit (RCU) reconstruction with costochondral graft (CCG) in pediatric patients, transport disk distraction osteogenesis (TDDO) in pediatric/adult patients, and total joint replacement (TJR) in adults followed by aggressive physical therapy (PT). Treatment is tailored to the patients age, duration and severity of ankylosis, associated deformity and requirement of future growth. Strategies for mitigation of reankylosis include interposing a barrier between temporal bone and cut end at ramus by temporalis muscle/fascia flap, fat packing and aggressive PT. Many of long standing TMJA patients will also have associated obstructive sleep apnea (OSA) due to retrognathia. A mandibular distraction should be performed before release. This increases the posterior pharyngeal airway space. In adults TJR with concomitant orthognathic surgery employing counterclockwise rotation of maxillomandibular complex is helpful.

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  The choice between CCG, TDDO, or TJR in the management of TMJ ankylosis depends primarily on age/growth status, extent of mandibular deformity, previous surgeries, condition of the joint and surrounding tissues, and expected functional outcomes ( Table 1 , Fig. 2 ).

  Table 1

  Table showing decision-making framework based on various clinical factors

  Clinical factor	Costochondral Graft	Transport Disk Distraction Osteogenesis	Total Joint Replacement
  Growing patient (<12 y)	Preferred	Useful in selected cases	Generally contraindicated except in multiple operated cases
  Adult patient	Less predictable	Selected cases	Preferred option
  Need for growth potential	Yes	Yes but limited	No
  Recurrent ankylosis (pediatric or adult)	Not favorable	Favorable	Strong indication
  Multiple previous surgeries (pediatric or adult)	Not favorable	Favorable	Strong indication
  Severe RCU deficiency	Good in pediatric	Good in pediatric/adult	Excellent in pediatric and adults
  Bilateral ankylosis	Good in pediatric	Technically demanding	Excellent in adults
  Need for immediate function	Moderate in pediatric	Good in pediatric & adult	Excellent
  Predictability	Variable in pediatric/adult	Variable in pediatric/adult	Highest
  Donor-site morbidity	Present	None	None

  

  Flowchart showing treatment modality for RCU reconstruction in temporomandibular joint ankylosis patients.

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  Children: CCG remains the standard reconstructive option for first time operation because of its growth potential.

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  Young patients with severe ramus deficiency: TDDO is an attractive biological alternative only in experienced hands.

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  Adults, especially recurrent ankylosis and failed reconstructions: TJR provides the most predictable functional and skeletal outcome and is increasingly regarded as the gold standard for TMJ ankylosis reconstruction.

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  Multiple failed arthroplasty in children or adults require TJR for restoration of function.

Selecting between a single-stage (resection and immediate joint reconstruction) and 2-stage (resection first, followed by delayed reconstruction) approach depends largely on patient age, the severity of the ankylosis, and anatomic complexities.

Single stage is preferred for adult cases (a) without extensive bony ankylosis, (b) have acceptable facial aesthetics before surgery, (c) who can maintain stable occlusion on CT imaging and, (d) fossa anatomy that requires only minor modifications ( Box 1 ).

The two-stage protocol involves osteoarthrectomy of the bony ankylosis and the placement of an inert spacer ( Fig. 3 ). A delayed secondary procedure is performed months later to reconstruct the joint with an alloplastic or autogenous graft. It is best suited for: (a) Significant bony ankylosis requiring extensive resection (b) Fossa or condyle anatomy needing major modification (c) Large tumor resections with associated hard-tissue defects (d) Removal of previously failed alloplastic hardware and, (d) Cases requiring significant occlusal changes. This has the advantage of confirmation of no reankylosis before placing the final prosthesis and provides time for presurgical orthodontic preparation, if orthognathic surgery is planned with joint replacement ( Boxes 2 and 3 ).

Intraoperative photograph of a patient showing silastic spacer fixed to temporal bone using wire as a temporary measure for Stage II definitive reconstruction.

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  Preoperative CT scans are carefully evaluated, and the full extent of ankylosis is delineated and marked.

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  The superior osteotomy is planned just inferior to the zygomatic arch, extending medially up to the full medial extent of the ankylotic mass. Any rudimentary or deformed condylar remnant, if present, should also be identified and excised.

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  The inferior osteotomy is planned approximately 1 to 1.5 cm below the superior cut, or as dictated by the planned fossa component in cases where TJR is contemplated.

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  If TJR is planned, the safe distance of osteotomy from middle cranial fossa (8 mm), external auditory canal (6–8 mm), and inferior osteotomy to lingula (3–4 mm) is measured.

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  In recurrent cases, a temporal bone breach may be present due to previous surgical intervention. If a defect is identified on CT imaging, a preoperative MRI should be obtained to rule out encephalocele and to facilitate appropriate planning—either for extended TJR alone or for a combined neurosurgical and maxillofacial surgical approach.