Mandible dislocation

Background

Anterior Dislocation

• Most common
• Mandibular condyle is forced in front of the articular eminence
• Risk factors: Prior dislocation, weak capsule, torn ligaments
• Often occurs spontaneously while patient is yawning, "popping" ears, or laughing

Posterior Dislocation

• Follows a blow to the mandible that may or may not break the condylar neck
• Condylar head may prolapse into the external auditory canal

Lateral Dislocation

• Often associated with mandibular fracture

Superior Dislocation

• Occur from blow to the partially opened mouth
• Associated with cerebral contusions, facial nerve palsy, deafness

Clinical Features

• Inability to close mouth
• Difficulty speaking or swallowing
• Malocclusion
• Pain localized anterior to the tragus
• Prominent-appearing lower jaw
• Preauricular depression
• Condylar head palpable in the temporal space (in lateral dislocation)

Posterior Dislocation

• Must examine the external auditory canal

Differential Diagnosis

Jaw Spasms

• Acute tetanus
• Akathisia
• Conversion disorder
• Drug toxicity (anticholinergic, phenytoin, valproate, carbamazepine)
• Dystonic reaction
• Electrolyte abnormality
  • Hypocalcemic tetany
  • Magnesium
• Mandible dislocation
• Meningitis
• Peritonsillar abscess
• Rabies
• Seizure
• Strychnine poisoning
• Stroke
• Temporomandibular disorder
• Torticollis

Evaluation

• Generally a clinical diagnosis
• For traumatic etiology, obtain CT face to evaluate for fracture
  • Also obtain CT IAC if concern for posterior dislocation
• Examine external auditory canal, especially in posterior dislocation
• Evaluate the cranial nerves to rule out concomitant injury

Management

• If no concern for fracture, perform closed reduction in the emergency department (see techniques below)
  • Often easiest to reduce one side at a time
• Provide pain control and anxiolysis as needed
• Consider procedural sedation, especially if the mandible has been dislocated for an extended period
  • Local anesthetic may also be effective when injected into the preauricular depression just anterior to the tragus

Syringe Reduction Technique

1. Have the patient place an empty 5 or 10 mL syringe between the upper and lower molars on one side of the mouth
2. Direct the patient to roll the syringe back and forth until reduction is achieved
3. If the opposite side does not spontaneously (it generally will), may repeat same technique on the opposite side

Extra-oral Reduction Technique

1. Place the patient in seated position
2. Place one thumb on the one zygomatic arch, and the fingers of the same hand behind the mandible
3. On the opposite side, place thumb on the coronoid process of the mandible
4. Use the fingers of the first hand to pull the mandible forward while using the zygomatic arch to brace
5. At the same time, apply firm and consistent pressure on the coronoid process with the second hand
6. Once the first side is reduced, reverse hand positions and repeat the process on the second side

Intra-oral Reduction Techniques

Wrist Pivot Method

1. Place patient in seated position
2. Face the patient and grasp the mandible with your thumbs at the apex of the mentum
3. Place well-wrapped and gloved fingers on the occlusal surface of the inferior molars
4. Apply cephalad force with the thumbs and caudal pressure with the fingers
5. Pivot your wrists to reduce joint

Traditional Technique

Posterior position

1. Place patient in seated position (anterior approach) or supine (posterior approach)
2. Place well-wrapped and gloved thumbs over occlusal surface of inferior molars or lateral to molars in the buccal fold
3. Apply caudal and posterior pressure to reduce joint

Disposition

• Generally may be discharged if uncomplicated and successfully reduced
  • Instruct patient to use soft diet, not to open mouth wider than 2cm for 2 weeks, and to support mouth when yawning
• Admit for:
  • Open dislocation
  • Superior dislocation
  • Fracture
  • Nerve injury
  • Inability to reduce