This document provides information on temporomandibular joint (TMJ) dislocation, including types, causes, signs and symptoms, diagnosis, and treatment. Some key points: - TMJ dislocation occurs when the mandibular condyle moves out of position in the glenoid fossa, preventing mouth closure. It can be acute or chronic. - Acute dislocations are usually anterior and cause inability to close the mouth, pain, and muscle spasms. Chronic dislocations involve fibrosis and joint degeneration. - Diagnosis is based on clinical exam showing inability to close the mouth and deviation of the chin. Imaging like panoramic x-rays or CT can confirm displacement of

1. DR. GIUSEPPE BRUNO PITASSI
’’A reminder for non-stomatologists healthcare professionals’’
G.B.Pitassi 2019

2. Reduction methods vary on the basis of the severity of the injury
and whether it is an acute or chronic dislocation.
Temporomandibular joint (TMJ) dislocation requires prompt medical
attention due to the crucial impact on the airway, nutrition, and
communication.
Recognition of this injury, based on clinical presentation and
history, is paramount for identification, both accurate diagnosis
and prompt treatment.
Preamble

3. Temporomandibular joint (TMJ) dislocation is an uncommon but
debilitating condition of the facial skeleton characterized by
displacement of the mandibular condyle from the glenoid fossa
that cannot be self-reduced.
Definition of temporomandibular dislocation

4. TMJ dislocation occurs when one or both mandibular condyles
move forward along the articular eminence into a position anterior
to the articular tubercle. Such abnormal position will cause TMJ
locking, (open lock) preventing the closure of the mouth.
From this location the condyles cannot be voluntarily reduced or
repositioned into the “glenoid fossa”.

5. Types of dislocations

6. Temporomandibular dislocation may be acute or chronic
•Acute TMJ dislocation:
Acute dislocation can usually occur in a hypermobile joint, where the
ligaments are loose and the condyle can move beyond the crest of the
articular eminence, it appearing to jump ″forward into a more wide
open position″.
Is common in clinical practice, occurring more often spontaneously as
”non-traumatic", during yawning, singing, eating in the absence of any
pathologic conditions as well as result of trauma, seizure, medication-
induced dystonia or excessive mouth opening but also during
endoscopy, laryngoscopy or prolonged dental procedures.
The mechanism that would induce an acute dislocation is attributable
to a disruption in the neuromuscolar coordination of the masticatory
muscles.

7. is a consequence of an acute dislocation that goes
unrecognized or undertreated.
Chronic dislocation is characterized by degenerative
condylar changes, dense periarticular fibrosis, and intra-
articular adhesions.
Chronic dislocation is rare and can require difficult and
invasive surgical intervention to correct the resultant
malocclusion and restore masticatory function.
•Chronic recurrent: dislocation:

8. Temporomandibular joint dislocation may be also classified based
on position as anterior, posterior, medial, lateral, or superior.
Anterior dislocation
Anterior dislocation is the most commonly seen, it occurs as the condyle is
displaced anteriorly to the crest of the articular eminence of the temporal bone.

9. Posterior dislocation
Medial & lateral dislocation
Superior dislocation
Posterior, medial, lateral, and superior dislocations are seldom encountered and are
typically associated with fracture of the condyle or temporal bone.

10. Temporomandibular joint dislocation may be also classified based
on symmetry as: ● Unilateral
In unilateral dislocation, the mandible deviates toward the healthy side.
Case courtesy of Dr Craig Hacking, Radiopaedia.org, rID: 57658

11. or: Bilateral
Bilateral dislocations occur more often than unilateral dislocations
and in this case , the mandible slides forward in a gaping mouth
opening that the patient is unable to close.

12. Pathophysiology
Temporomandibular joint (TMJ) is an unusual diarthrodial joint with
both sliding and hinge type of movement permitting freedom of
movement.

13. Pathophysiology
Translational Movement
1st stage mandibular
rotational movement with
the condyles in the
terminal hinge position
(pure rotational opening)
2nd. stage mandibular
rotational movement
during opening.

14. Condylar movement is dictated by the complex coordination of
multiple muscle groups.
Medications or conditions such as seizure, myotonic dystrophy, or multiple sclerosis that
adversely affect motor coordination also carry a greater risk of dislocation.

15. The anterior limit of condylar translation is determined by the size
and laxity of the temporomandibular capsule and ligaments, and
on the actions of the masticatory musculature.

16. Bell described the critical period when TMJ dislocation can
occur at the initial point of mandibular closure when the
condylar head is positioned anteriorly at the glenoid fossa
and at the same time at the level of the top of the crest of
the articular eminence.
Once the dislocation has established, significant muscle
spasm, trismus and pain will perpetuate the dislocation
preventing its reduction as well as eventual fibrosis of the
masticatory muscles will prolong the dislocation over time.
Contraction of the masseter, temporalis, and medial
pterygoid muscles before relaxation of the lateral pterygoid
muscle pushes the condyle anteriorly into the infratemporal
fossa.
Disruption of the normal sequence of muscle contracture
and relaxation can result in forward luxation of the
condyle.
Sequence of TMJ dislocation

17. TMJ’s dislocation
signs, clinical presentation and its clinical features
Diagnosis of TMJ dislocation is based on clinical examination and
confirmed by imaging studies.
Any previous history of dislocation or other TMJ pathology should
be established.
Radiographic findings alone are insufficient to diagnose a TMJ
dislocation.
A detailed history should be obtained to determine the duration of
the dislocation and potential inciting cause.
A comprehensive TMJ examination should be completed on any
patient with a suspected dislocation.

18. Upon physical examination, the patient is unable to close the
mouth.
Acute dislocation is easy to recognize clinically
During anterior dislocation, the mandible protrude forward. The
patient will complain of acute pain in the affected joint and
associated muscles of mastication, masseter muscle spasm and
discomfort.
Because of this, the salivation can be extreme, then drooling occur
and communication (speaking), nutrition etc. etc. will be very
difficult.

19. Dislocation can be both bilateral and unilateral.
In acute dislocation, pain in the pre-auricular region is present, but
chronic recurrent dislocation is rarely associated with it.
In rare cases, dislocation can be unilateral, in this case, the
practitioner will typically see the chin deviate laterally always to the
contralateral side.
Palpation over the preauricular region may suggest emptiness in
the joint space associated with preauricular depression or dimpling
that can be often be visualized and palpated.

20. Dislocation may be irreducible and one or two condyles remain
dislocated (luxation).
In the latter condition, the mouth remains open and the front teeth
do not meet, due to the action of the elevator muscles with or
without lateral deviation depending on whether the dislocation is
unilateral or bilateral.
Then the patient will show up in the first aid post, agitated by the
impossibility of closing the mouth, suffering from facial pain and
often drooling as unable to swallow due to forced open bite.

21. Clinical features
Bilateral dislocation is characterized by an elongated face
and prognathic profile.
The most common type of temporomandibular joint (TMJ)
dislocation is an acute episodes of anterior dislocation.
The mandibular condyles are not palpable within the glenoid
fossae and laterognatia.

22. Clinical features
The patient frequently exhibits a significant
anterior open bite and collapse of the posterior
vertical occlusal height.
Unilateral dislocation presents with
deviation of the mandible away from
the dislocated joint and contralateral
occlusal crossbite.
Mandibular movements are limited, associated with impaired masticatory
function, severe pain, and muscle spasms.

23. Radiological Diagnostics and Imaging
CT imaging of the face can be useful to rule out condylar fracture
in the setting of a traumatic dislocation or to evaluate for
degenerative changes of the condyle with chronic dislocation.
There are a number of techniques available for imaging patients
with temporomandibular joint (TMJ) dislocation.
These techniques include conventional radiography, panoramic
radiography, conventional tomography, arthrography, computed
tomography (CT), ultrasound (US), and magnetic resonance
imaging (MRI).

24. Panoramic radiograph or plain films of the mandible are often
sufficient to confirm diagnosis of a TMJ dislocation and they are
anyway standard exams of first instance.
Case Dr. D. A. Baur
Case courtesy of Dr David Holcdorf, Radiopaedia.org, rID: 53530
Case courtesy of Dr Craig Hacking, Radiopaedia.org, rID: 57658

25. During anterior dislocation, OPG will demonstrate condyles out of
the fossa often bilaterally and showing the location of the condylar
head anteriorly to the articular eminence (anterior
temporomandibular joint dislocation).
If OPG films are not available, the practitioner can use plain
radiographs to assist in making the diagnosis.
Specifically, plain radiographs, for imaging of the ramus and
condylar process, transcranial, lateral oblique, reverse Towne,
posterior-anterior (PA) mandible and skull projections are most
suitable, they provide an anteroposterior, bilateral, and
submental-vertex views.

26. Anterior dislocation in a lateral view
Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 6271
Anterior dislocation in a lateral view
Case courtesy of Elizabeth K Asfaw, Radiopaedia.org, rID: 5154
Case courtesy of Dr Henry Knipe, Radiopaedia.org, rID: 27600

27. If plain radiographs show negative findings and the practitioner still
suspects TMJ dislocation, Ct-scan facial bone can be used to help
evaluate the TMJ as well as other bones in the face.
CT Sagittal, non-contrast
Case courtesy of Dr Matthew Lukies, Radiopaedia.org, rID: 59430
CT Axial, non-contrast
Case courtesy of Prof Cláudio Souza, Radiopaedia.org, rID: 13947

28. Both MDCT (Multidetector Helical CT) and CBCT (Cone Beam
Computed Tomography) are excellent techniques for assessing
osseous anatomy and fine bony detail and are widely used for
imaging of the mandible and skull base. However, CBCT images
typically have poorer soft tissue contrast compared to MDCT.
CT assessment is typically performed with the patient in maximum
intercuspation. Additional CT imaging should not be used to assess
the patient in open mouth position, as this increases the radiation
burden for the patient.
CT is frequently the preferred imaging study for evaluating patients
with facial trauma and suspected TMJ dislocation, because it
nicely depicts condylar position and orientation, as well as
associated fractures of the mandible and glenoid fossa.

29. CT is also useful for assessing skeletal factors that may predispose
to TMJ dislocation, including the morphology of the condyle and
articular eminence and the size of the glenoid fossa.
Small, short, or atrophic condyles, atrophic articular eminences,
and small, shallow glenoid fossae all predispose to TMJ
dislocation, while an elongated articular eminence may impede
the ability to reduce the condyle after it has been dislocated.
3D reconstruction of CT scan demonstrating anterior dislocation of the TMJ

30. MRI
Magnetic Resonance Imaging
MRI is not commonly used to evaluate TMJ dislocation. It is
generally reserved to evaluate chronic TMJ changes and internal
derangement.
Generally speaking, if the primary clinical interest revolves around
the osseous structures, panoramic radiography and CT are the
preferred examinations.
If the primary question is instead related to the soft tissues, including
the articular disc, joint capsule, or surrounding musculature, MRI is
the preferred test.
In the urgent care or emergency department setting, MRI imaging
may be warranted only to confirm the diagnosis of TMJ dislocation
and to search for associated fractures.

31. Acute TMJ Dislocation and Technique of Manual Reduction
The most popular procedure of reduction is the “Hippocratic
method” also the one used almost exclusively.
Classically, acute anterior-superior dislocations of the TMJ can be
managed conservatively with manual reduction.
Immediate reduction is often easier as there is less time for muscle
spasm to develop which makes the reduction more difficult.
Almost all patients can be successfully reduced without the
adjunctive use of anesthesia or other pharmacotherapies,
especially if reduced immediately.
Some patient, honestly very few, from my point of view, experience
a significant amount of pain from the joint and distress from
masticatory muscle spasm, making the administration of local
anesthesia, IV. sedatives, narcotic or other major pain medication,
necessary to facilitate the reduction maneuver.

32. The practitioner's thumbs will be used to apply downward pressure
(inferiorly) over the molars of the lower jaw using nonsterile gauze
or a foam finger splint, followed by pushing the mandible
posteriorly with the remaining fingers wrapped around the body of
the mandible.
In the Hippocratic method, the practitioner will stand in front of the
patient with an anterior TMJ dislocation. With gloved hands, the
practitioner's fingers are positioned laterally around the mandible.

33. Recumbent/Reclined approach

35. Post-Reduction Management
Goals of post-reduction management center around avoiding re-
dislocation of the condyle and allowing sufficient time for the
ruptured ligaments and capsule, to eventually heal and strengthen.
This is accomplished by a period of restriction or immobilization of
the joint. Most authors recommend a 7-day period of
restriction/immobilization which can be achieved using a
facioplasty elastic bandage or even using maxillomandibular
fixation with Erich arch bars or IMF screws.
The patient’s head is wrapped with an
elastic bandage, and he/she is
instructed to use a closed fist to restrict
excessive mouth opening.
A prescription for post-reduction pain
medications and antispasmodics
should be considered.

36. Thank you

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