Jaw Dislocation

Joe Lex, MD, FACEP, MAAEMClinical Professor of Emergency Medicine

Department of Emergency MedicineTemple University School of Medicine

Philadelphia, PA USA joe@joelex.net @JoeLex5

Odds & Ends

• Mandere (L): to chew• Late Latin: mandibula• Middle French: mandible (late 14th C.)• NOT just a “hinge joint”–Hinge joints allow movement in only one

plane: ankle, elbow, and knee

BALL ANDSOCKET

Distal bone capable of motion around

indefinite number of axes

BALL ANDSOCKET

CONDYLOID(ELLIPSOID)

SADDLE

HINGE PIVOTMovement in two planes: flexion, extension, adduction, abduction, circumduction

BALL ANDSOCKET

CONDYLOID(ELLIPSOID)

SADDLE

HINGE PIVOT

Like condyloid joint but no axial rotation; movement only in sagittal and frontal planes

BALL ANDSOCKET

CONDYLOID(ELLIPSOID)

SADDLE

HINGE PIVOT

Motion in only one plane

BALL ANDSOCKET

CONDYLOID(ELLIPSOID)

SADDLE

HINGE PIVOT

Rotation only: pronation, supination

ANDTHEJAW

IS?

“ginglymoarthrodial” both ginglymus

(hinging joint) and arthrodial

(sliding joint)

Mandibular condyle articulates with temporal bone in mandibular fossa

Mandibular fossa: concave depression in squamous portion of temporal bone

Bones separated by articular disc divides TMJ into 2 distinct compartments

Some Anatomy

• Inferior compartment allows rotation of condylar head around an instantaneous axis of rotation

• First ~20mm of mouth opening• Then mouth can no longer open without

superior compartment of TMJ active

Some Anatomy

• After 20 mm, not only is the condylar head rotating within the lower compartment, but the entire apparatus translates

• Feel translation by putting your fist against your chin, then try to open your mouth more than 20 mm

Some Anatomy

• Resting position of TMJ is not with teeth biting together

• Muscular balance and proprioceptive feedback allow a physiologic rest

• There’s an interocclusal clearance or freeway space of 2 to 4 mm

Some Anatomy

• Normal full jaw opening: 40-50 mm• Only mandible moves during jaw

movement• Normal mandible movements during

chewing are called excursions

Some Anatomy

• Two lateral excursions: left and right• Forward excursion: protrusion• Reversal of protrusion: retrusion

B I T E M

BuccinatorInternal (medial) PterygoidTemporalisExternal (lateral) PterygoidMasseter

JAW DISLOCATION

ANTERIORJAW

DISLOCATION

Usually after yawning or chewing

POSTERIORJAW

DISLOCATION

Punch in the chin

SUPERIORJAW

DISLOCATION

Punch in the chin with open mouth

LATERALJAW

DISLOCATION

Usually only with jaw fractures

ANTERIORJAW

DISLOCATION

Bilateral or unilateral after yawning

POSTERIORJAW

DISLOCATION

Punch in the chin

SUPERIORJAW

DISLOCATION

Punch in the chin with open mouth

LATERALJAW

DISLOCATION

Usually only with jaw fractures

Reduction

Traditional

• Most common: intraoral route• You: gloved with thick gauze taped

securely on both thumbs• Place thumbs on lower molars or on

ridge of the mandible intraorally, posterior to molars, with your fingers wrapped externally around mandible

Traditional

• With patient positioned so mandible is below level of your elbows, apply firm, slow, and steady pressure in a downward and posterior direction

• If bilateral reduction is not possible, you can reduce one side at a time

Traditional

• You may need procedural sedation• You may need intravenous analgesia• You may get bitten

A New Concept

The “Syringe” Technique: A Hands-Free Approach for the Reduction of Acute Nontraumatic Temporomandibular Dislocations in the Emergency DepartmentJulie Gorchynski, Eddie Karabidian, Michael SanchezThe Journal of Emergency Medicine, Volume 47, Issue 6, December 2014, Pages 676–681

Wow – really??

• 31 patients with acute nontraumatic TMJ dislocation

• 30 had successful reduction• 24 were reduced in less than 1 minute• No recurrent dislocations at 3 day follow-

up

Equipment

OR

THAT’SIT!

Technique

• Patient in sitting position• Place syringe between posterior upper

and lower molars or gums• Have patient gently bite down and roll

syringe back and forth

Technique

• Syringe size depends on distance between upper and lower molars / gums and patient’s ability to open mouth

• Syringe acts as rolling fulcrum • As molars / gums roll over syringe

mandible glides posteriorly

Technique

• Anterior displaced condyle moves posteriorly

• Masseter, pterygoid, and temporalis muscles work in concordance

• Condyle slips gently back into its normal anatomical position

Advantages

• No procedural sedation• No intravenous analgesia• Technique is simple and fast• Technique is comfortable to patient• Significantly reduced time in ED• Lower cost: no procedural analgesia,

critical care monitoring or nursing care

…and best of all

NO BITTEN THUMB!!

JOE@JOELEX.

NET