TMJ Hypermobility/dislocation

Question 1

3 types of hypermobility

Answer 1

Acute dislocation
Recurrent dilocation
Long-standing chronic dislocation

Question 2

Causes of dislocation

Answer 2

Anatomically

1. Articular eminence too short causing excessive translation of the condyle out of the fossa - may easily be reduced by self
2. Too deep articular eminence with joint laxity causing condylar dislocated behind AE. And unable to relocate back to the fossa.

Disease cause:

1. Chronic subluxation with prolonged wide mouth opening
2. Looseness or laxity in the joint capsule
3. CT disorders (marfan syndrome, ehlers danlos syndrome)
4. Seizure disorders
5. Parkinsonism
6. Drug induced tardive dyskinesia

Question 3

Causes of dislocation of tmj

Answer 3

1. Joint laxity
2. long-standing internal derangement, and spasm of the lateral pterygoid muscles
3. Structural deficit:
   arthritic changes - flattening or narrowing
   morphological changes - articular eminence, glenoid fossa, zygomatic arch, squamotympanic fissure
4. Over function
   - forceful wide opening eg. yawning, laughing, vomiting, or seizures
   - dental treatments like third molar extractions
   - endotracheal intubation, laryngoscopy, and trans oral fiber optic bronchoscopy
5. antipsychotic meds
6. Syndromes (ehlers danlos syndrome, marfan syndrome - CT disorder)

Question 4

Emergency or primary treatment for joint dislocation

Answer 4

1. Bimanual reduction. Pressing on the posterior mandible downwards to stretch the spastic masticatory muscles and release from AE. And then push backwards to snap back into the glenoid fossa
2. Medications:
   muscle relaxant (chlorobenzaprine 5mg)
   anxiolytic (diazepam)
3. Limit jaw movement 1-2 weeks. Soft diet. To allow stretched muscles to heal.

Question 5

Recurrent dislocation management

Answer 5

1. Nonsurgical
   - botox (botulinum toxin injexction) to lateral pterygoid muscle - 1 week latency period. Avoid frequent injections
   - intraarticular injections of sclerosing agent or blood into superior joint space to stimulate capsular fibrosis
2. Surgical.
   Eminectomy - to remove AE to allow condyle to move freely

Capsulorraphy - portion of capsule is excised and primary closure to reduce the size of capsule. Additional temporalis fascia flap sutured to the capsule to further limit condyle translation.
Dautrey procedure - downfrvture of the zygomatic arch to recreate and deepen the articular eminence - to limit the condylar translation
Lateral pterygoid myotomy - in persistent etiology such as parkinsonism, seizure. This prevents mandibular translation.

Question 6

Complications of fracturing the zygomatic arch or eminectomy

Answer 6

1. Perforation of middle cranial fossa
2. Pneumatization of articular eminence leading to spread of infection to temporal bone
3. Bleeding from middle meningeal artery, internal maxillary artery, carotid artery, pterygoid plexus.

Question 7

Chronic persistent dislocation

Answer 7

Usually occur unilaterally. Hence jaw movement achieved by unaffected tmj.

On top of the other surgeries.
they require temporal myotomy and releasing of the temporal attachment from the coronoid bilaterally because of the severe fibrosis and muscle contraction on both sides.

Question 8

Tx for recurrent dislocation or a persistent long standing dislocation

Answer 8

Myotomy
Aminectomy
Blocking procedures (dautery surgery, le clerc osteotomy)
Intraarticular injection
Discectomy (only corrects the problem of the disk displacement that accompanies dislocation)