Temporomandibular Joint Ankylosis

Temporomandibular joint (TMJ) ankylosis is the fusion of the mandibular condyle to the glenoid fossa by fibrous tissue or bone, resulting in severe loss of mouth opening (interincisal opening under 20 mm, often under 10 mm). It is classified as true (intra articular: fibrous, fibro osseous, bony) or false (extra articular, from coronoid hyperplasia, scarring of the masticatory muscles, burns, or oral submucous fibrosis).

Trauma, particularly mandibular condyle and symphysis fractures in children from falls, is the commonest cause worldwide; infection (otitis media, mastoiditis, osteomyelitis, tuberculosis, septic arthritis) is more frequent in low income settings; systemic arthropathy (juvenile idiopathic arthritis, ankylosing spondylitis, rheumatoid arthritis) and previous joint surgery are others.

Onset in childhood stunts mandibular growth, causing a bird face deformity with micrognathia, retrognathia and obstructive sleep apnoea. Without release, nutrition, hygiene, speech and airway are compromised. Recurrence after surgery is 5 to 50 percent depending on the technique and compliance with physiotherapy.

• Progressive painless inability to open the mouth over months to years; severe limitation of mouth opening (often 0 to 15 mm), no condylar translation on palpation.
• History of facial trauma or infection, often in childhood.
• Facial asymmetry (unilateral: chin deviates to the affected side, flattened face), bird face deformity (bilateral), antegonial notching, class II malocclusion, open bite.
• Poor oral hygiene, extensive dental caries, malnutrition, difficulty with speech and chewing.
• Obstructive sleep apnoea with snoring, daytime sleepiness, in severe retrognathia; difficult airway for anaesthesia.
• Red flags: respiratory distress in sleep, rapid mouth opening loss with fever (active infection), growth failure in children.

• History of trauma, infection, or arthritis; measurement of interincisal opening (normal 40 to 55 mm); movements (lateral excursion absent or near absent); palpation of condyles.
• CT of the TMJ with 3D reconstruction (coronal and sagittal sections): bony fusion mass, loss of joint space, flattened condylar head, enlarged coronoid process, and the depth from the cranial base to the medial extent of the fusion mass.
• Panoramic radiograph: reduced joint space, bony union; MRI where fibrous ankylosis or soft tissue involvement is suspected.
• Polysomnography when sleep apnoea is suspected; nasendoscopy and anaesthetic assessment of the airway.
• Laboratory tests in infection (full blood count, ESR, C-reactive protein, Mantoux or GeneXpert) and rheumatological screening (rheumatoid factor, HLA-B27) when indicated.
• Exclude coronoid hyperplasia, oral submucous fibrosis, scleroderma, myositis ossificans, trismus from tetanus or infection, TMJ osteoarthritis, and neoplasm.

• Definitive treatment is surgical: gap arthroplasty (removal of 10 to 15 mm of the bony block, with a gap of at least 1 cm), interpositional arthroplasty (temporalis muscle flap, fascia, costochondral graft, silicone is not used), or total joint replacement (alloplastic prosthesis) in adults with recurrent or severe disease; ipsilateral coronoidectomy when mouth opening is under 35 mm intraoperatively; contralateral coronoidectomy when still limited.
• Airway: awake fibre optic nasal intubation, or tracheostomy, since conventional laryngoscopy is impossible.
• Reconstruction in children: costochondral graft to restore ramus height and growth, with distraction osteogenesis for later correction of deformities.
• Perioperative antibiotics: cefazolin 1 to 2 g intravenously (children 25 mg/kg) at induction, and continued for 24 hours (repeat every 8 hours).
• Postoperative physiotherapy is mandatory and begins early (24 to 48 hours): jaw opening exercises with a mechanical jaw exerciser or stack of tongue depressors, 10 repetitions 6 to 10 times a day for 6 to 12 months, to maintain opening over 35 mm.
• Analgesia: paracetamol 1 g every 6 hours and ibuprofen 400 mg every 8 hours; short course opioids; anti-inflammatory dose for heterotopic ossification prevention (indomethacin 25 mg three times daily for 2 weeks is used in some units).
• Underlying disease: infection treated by drainage and appropriate antibiotics; juvenile arthritis with methotrexate 10 to 15 mg/m2 orally weekly with folic acid 5 mg weekly.
• Nutrition: high calorie liquid diet, dietician support.
• Follow up: every 2 weeks for 3 months, monthly to 6 months, then 3-monthly to 2 years, with measurement of opening and radiographs at 6 and 12 months. Late orthognathic surgery or distraction osteogenesis for residual deformity.
• Counselling: adherence to exercises is the main determinant of success; avoid trauma, and treat ear and facial infections early.