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REVIEW Open Access
Evaluation of the mechanism and principles of
management of temporomandibular joint
dislocation. Systematic review of literature and a
proposed new classification of temporomandibular
joint dislocation
Babatunde O Akinbami
Abstract
Background: Virtually all the articles in literature addressed only a specific type of dislocation. The aim of this
review was to project a comprehensive understanding of the pathologic processes and management of all types
of dislodgement of the head of the mandibular condyle from its normal position in the glenoid fossa. In addition,
a new classification of temporomandibular joint dislocation was also proposed.
Method and materials: A thorough computer literature search was done using the Medline, Cochrane library and
Embase database. Key words like temporo-mandibular joint dislocation were used for the search. Additional manual
search was done by going through published home-based and foreign articles. Case reports/series, and original
articles that documented the type of dislocation, number of cases treated in the series and original articles.
Treatment done and outcome of treatment were included in the study.
Result: A total of 128 articles were reviewed out which 79 were found relevant. Of these, 26 were case reports, 17
were case series and 36 were original articles. 79 cases were acute dislocations, 35 cases were chronic protracted
TMJ dislocations and 311 cases were chronic recurrent TMJ dislocations. Etiology was predominantly trauma in
60% of cases and other causes contributed about 40%. Of all the cases reviewed, only 4 were unilateral dislocation.
Various treatment modalities are outlined in this report as indicated for each type of dislocation.
Conclusion: The more complex and invasive method of treatment may not necessarily offer the best option and
outcome of treatment, therefore conservative approaches should be exhausted and utilized appropriately before
adopting the more invasive surgical techniques.
Introduction
The mechanism of temporomandibular joint dislocation
varies depending on the type of dislocation which may be
acute, chronic protracted or chronic recurrent dislocation
[1]. This mechanics is closely related to the structure and
function of the temporomandibular joint as well as the
dynamics of the masticatory system [1]. The capsule of
the joint is the most important structure which stabilizes
the joint reinforced by the lateral ligaments [2,3].
However displacement of the head of the condyle out of
the glenoid fossa is also greatly influenced by the mor-
phology of the condyle, glenoid fossa, articular eminence,
zygomatic arch and squamotympanic fissure [1,3-5]. The
afore-mentioned factors mainly determine the type and
direction of dislocation. In addition, age, dentition, cause
and duration of the dislocation as well as the function of
the masticatory muscles contribute significantly in the
mechanism and management of temporomandibular joint
dislocation [4-7]. The outcome of T.M.J dislocation, espe-
cially the chronic recurrent and chronic protracted
are not very predictable and this depend on thorough
Correspondence: akinbamzy3@yahoo.com
University of Port Harcourt Teaching Hospital, Port Harcourt, Rivers State,
Nigeria
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HEAD & FACE MEDICINE
© 2011 Akinbami; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
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evaluation, treatment planning and compliance of the
patient [3-9].
The aim of this article is to review, analyze and update
the mechanisms and various management options avail-
able for the different types of T.M.J dislocation in
literature.
Methods and materials
A thorough computer literature search was done using
the Medline, Cochrane library and Embase database.
Key words like temporo-mandibular joint dislocation
were used for the search. Additional manual search was
done by going through published home-based and for-
eign articles. Relevance of article for inclusion into the
study was assessed based on the title, abstract and con-
tents of the full article. The reference list of the
reviewed articles was also searched from Medline and
Embase database as well as the Thomson Reuters, Wol-
ters Kluwer, Lippincott Williams and Wilkins search
engines for Cited and Related literature search based on
the relevant title. Case reports/series, and original arti-
cles that documented the type of dislocation, number of
cases treated in the series and original articles. Treat-
ment done and outcome of treatment were included in
the study. Total number of each type of dislocation
reported was recorded and the treatment options for
each type was analyzed based on the clinical and radi-
ological outcome (presence/absence of pain, occlusion
derangement, inter-incisal distance, deviation of the
mandible and masticatory function, as well as position
of the condylar head in the glenoid fossa). A new classi-
fication was proposed for Temporomandibular joint dis-
location based on the position of the condylar head in
relation to the articular eminence.
Results
A total of 128 articles were reviewed out which 79 were
found relevant. Of these, 26 were case reports, 17 were
case series and 36 were original articles. 79 cases were
acute dislocations, 35 cases were chronic longstanding
TMJ dislocations and 311 cases were chronic recurrent
TMJ dislocations(Table 1). Etiology was predominantly
trauma in 60% of cases and this include fall, road traffic
accident, domestic accidents, interpersonal violence; other
causes like excessive mouth opening from yawning, laugh-
ing, singing, prolonged mouth opening from oral and ENT
procedures, forceful mouth opening from anaesthetic and
endoscopic procedures contributed about 40%.
Of all the cases reviewed, only 4 were unilateral dislo-
cation. Prognatism of the lower jaw, anterior cross bite
and open bite were the classical features in the bilateral
cases while deviation of the mandible, shift in the mid-
line to the unaffected side and cross bite on that side
were predominant in the unilateral cases.
Acute dislocation was treated by manual reduction in 63
cases without any form of anaesthesia while 2 cases were
treated under IV analgesia and sedatives, and manual
reduction was achieved in 14 cases under general anaes-
thesia, 3 cases were reduced with gag reflex (Table 2).
Chronic protracted TMJ dislocations were treated by
manual Hippocratic method under G.A in 13 cases, a
hook was used to apply traction on the sigmoid notch
in 1 case, external elastic traction with arch bars and
elastic bands was used in 1 case while assisted open
reduction with Bristow’s elevator was done in one case
(Table 3). Vertical-oblique ramus osteotomy was used to
correct prognatism and anterior open/cross bite in 9
cases, inverted L osteotomy was used in 1 case and
sagittal split osteotomy was used in 1 case (Table
3contd).
The number of cases treated by chemical capsulora-
phy using sclerosing agents and platelet rich plasma
could not be ascertained, 9 cases were treated with
autologous blood in the superior joint space and 9 cases
with injection into the space and pericapsular tissues.
Also, number of cases of chronic recurrent dislocation
that received surgical capsuloraphy and placation for lax
capsule and ligaments was not obtained. Closed low
Table 1 Distribution of the articles reviewed and type of
dislocation
Parameter Frequency
No. of articles reviewed 128
No. of relevant articles 79
Type of articles
Case reports 26
Case series 17
Original articles 36
Type of dislocation
Acute 79
Chronic 35
Recurrent 311
Superior 8
Medial 11
Lateral 2
Bilateral 421
Unilateral 4
Table 2 Treatments useful for Acute dislocation
Treatment No. of
patients
Manual reduction without anaesthesia 63
Manual reduction with Local Anaesthesia (L.A)+
sedation
2
Reduction with gag reflex 3
Manual reduction with General Anaesthesia (GA) 13
Assisted (open) reduction with General Anaesthesia 1
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level condylotomy to allow free movement was done in
2 cases while 4 cases received open condylotomy. Fif-
teen cases were treated with lateral pterygoid myotomy
via intraoral approach (Table 4contd).
Also, 101 cases of chronic recurrent dislocation were
treated with eminectomy to shorten the articular emi-
nence and allow unrestricted movement/spontaneous
reduction of the condylar head. Eminoplasty using mini-
plates was done in 24 patients and screws was used in
3 cases (Table 4contd).
There were problems of severe pain and resorption
of condylar head and eminence in 20% of cases with
screws. Augmentation of the height of eminence by
eminoplasty using bone grafts was done on some
patients, 4 patients received interpositional (inlay) emi-
noplasty without need for wiring or plating while
60 received eminoplasty with onlay grafts wired to the
articular eminence. Modified mini-invasive eminectomy
and relocation of the lateral pterygoid muscle was done
in 1 case.
Similar procedure was done for both sides in each
bilateral case of chronic protracted and recurrent dislo-
cation. Majority of the cases were adequately followed
up for a period of 2-5 years and complications were
mainly found in the patients that did eminoplasty with
screws. Patients with autologous blood injected around
the pericapsular tissues and into the superior joint space
had less recurrence rate than those injected into the
space alone.
Discussion
Aetio-pathogenesis of Temporomandibular Joint
Dislocation
Dislocation of the temporomandibular joint is the dis-
lodgement of the head of the condyle from its normal
position in the glenoid fossa located in the squamo-tem-
poral portion of the cranial base. It can be partial (sub-
luxation) or complete (luxation), bilateral or unilateral,
acute, chronic protracted or chronic recurrent [7-29].
Also, it can be anterior-medial, superior, medial, lateral
or posterior dislocation and the cause is either sponta-
neous or induced by trauma, [30-80] forceful mouth
opening from endotracheal intubation with laryngeal
mask or tracheal tube, ENT/Dental procedures, endo-
scopy, excessive mouth opening from yawning, laughing,
vomiting and also during seizures [81-84,94,96-111].
Altered structural components include a lax capsule,
weak ligaments, small/short and atrophic condyle,
atrophic articular eminence, elongated articular emi-
nence, hypoplastic zygomatic arch and small, poorly
grooved glenoid fossa. Predisposing factors include epi-
lepsy, severe vomiting, Ehlers-Danlos syndrome and
Marfan’s syndrome and dystonic movements from the
effect of major tranquilizers/neuroleptics used for
neuro-psychiatric diseases [5,28,46,51,68,116].
Anterior dislocations are the most common and occur
due to displacement of the condyle anterior to the
articular eminence of the temporal bone. Anterior dislo-
cations are usually secondary to an interruption in the
normal sequence of muscle action when the mouth
closes from extreme opening [30]. The masseter and
temporalis muscles elevate the mandible before the lat-
eral pterygoid muscle relaxes resulting in the mandibu-
lar condyle being pulled out of the glenoid fossa and
anterior to the bony eminence. Spasm of the masseter,
temporalis and pterygoid muscles causes trismus and
keeps the condyle from returning into the glenoid fossa
[30].
Posterior dislocations typically occur secondary to a
direct blow to the chin. The mandibular condyle is
pushed posteriorly toward the mastoid [34]. Injury to
the external auditory canal from the condylar head may
occur from this type of injury.
Superior dislocations, also referred to as central dislo-
cations, can occur from a direct blow to a partially
opened mouth. The angle of the mandible in this posi-
tion and small rounded margined condyle head predis-
poses to upward migration of the condyle. This can
result in fracture of the glenoid fossa with mandibular
Table 3 Treatments Useful for Chronic protracted
dislocation
Conservative Treatment of Chronic protracted
dislocation
No. of
patients
Manual reduction without anaesthesia 0
Manual reduction with Local Anaesthesia (L.A)+ sedation 1
Manual reduction with L.A + sedation + nerve block 1
Manual reduction with General Anaesthesia (GA) 13
Assisted (open) reduction with General Anaesthesia 1
Elastic traction with Intermaxillary fixation 1
Traction with bone hook 1
Mandibular guidance therapy 1
To reposition condyle in fossa (There was much
restriction of movement)
Temporalis Myotomy 4
High Condylotomy ?
To correct fusion and restore the joint (There was
complete restriction of movement)
Low Condylotomy ?
Condylectomy (for chronic lateral dislocation) 2
Gap Arthroplasty (for superior dislocation) 8
To maintain new joint and correct occlusion (There
was little restriction of movement)
Horizontal subsigmoid osteotomy ?
Vertical/Oblique Osteotomy 9
Inverted L Shaped Osteotomy 1
Bilateral Sagittal Split Osteotomy 1
Midline Mandibulotomy 1
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condyle dislocation into the middle skull base
[26,35,52,109]. Further injuries from this type of disloca-
tion can range from facial nerve injury, to intracranial
hematomas, cerebral contusion, leakage of cerebrospinal
fluid, and damage to the eighth cranial nerve resulting
in deafness. Medial dislocations are second to anterior
dislocations. Avrahami et al. [110] documented 11 cases
of medial dislocation and stated that they occur due to
the sustained pull of the lateral pterygoid muscle on the
condyle of the affected side.
Lateral dislocation is usually associated with mandible
fractures. It could be type I (subluxation) or type II (luxa-
tion). Type II has been further sub-classified into three,
depending on the duration and management applicable.
The condylar head migrates laterally and superiorly and
can often be palpated in the temporal space [8,9,61].
Acute dislocation presents within 2 weeks and it is
readily reducible by the Hippocratic maneuver. After 2
weeks, spasms and shortening of the temporalis and
masseter muscles occur and reduction becomes difficult
to achieve manually. This leads to the commencement
of chronic protracted dislocation. Also, elongated articu-
lar eminence may prevent the sliding back of the head
of the condyle into the normal position in the glenoid
fossa, in this case, a chronic protracted dislocation with
formation of a new pseudojoint with varying degree of
movement sets in and such patients have problems with
difficulty in closing the mouth (open lock) and deranged
occlusion in which there is prognathism of the mandible
with anterior cross bite [70].
In cases due to trauma, fibrous and bony consolidation
occur anterior to the articular eminence following the
sustained pull of lateral pterygoid and head of condyle
resulting in ankylosis and deranged occlusion [31,34,63].
Chronic recurrent dislocations which include those due
to habitual wide mouth opening are usually spontaneous
and self reducible depending on the degree of alteration
of the morphology of the temporomandibular joint and
the contiguous structures. When the articular eminence
is long, the dislocation will not be easily self reducible. It
occurs commonly in patients with hypoplastic eminence,
narrow fossa, lax capsule, collagen disorders, small con-
dyle, hypermobility syndromes, oromandibular dystonias
and use of neuroleptic drugs [17,18]
Plain T.M.J views especially the transcranio-oblique
views, plain and contrast CT scans, i-CAT scans and
MRI, linear and rotational plain digital tomograms, are
joint arthroscopy are useful to assess the position of the
head of the condyle and meniscus in relation to the gle-
noid fossa, mastoid process, tympanic plate and articular
eminence. Recent imaging tools include the Dolphin
imaging system which imports 2D facial photographs
(facial wrap) on 3D stereographic images to enhance
treatment simulation [40,41,55].
Newly Proposed Classification of TMJ Dislocation based
on the position of the head of the condyle to the
articular eminence
The author has classified dislocation based on relation-
ship of the head of mandibular condyle to the articular
eminence seen on clinico-radiological evaluation into
three types (I-III).
Type I - the head of condyle is directly below the tip of
the eminence
Type II - the head of condyle is in front of the tip of
the eminence
Type III - the head of condyle is high up in front of
the base of the eminence.
Conservative and Surgical Interventions in TMJ
Dislocations
Cases of acute antero-medial, medial, lateral, or poster-
ior dislocation can be reduced manually under local or
Table 4 Treatments useful for Chronic Recurrent
Dislocation
Conservative Treatment of Recurrent dislocation No. of
patients
Chemical Capsuloraphy ?
Alcohol
Rivanol(aethedicaine)
Sodium monoruate
Sodium psyliate (Sylnasol)
Sodium tetradecyl sulphate
Autologous blood capsuloraphy 18
Platelet rich plasma capsuloraphy ?
Botulinium toxin A toxin muscle injection 2
To restrict condylar movement
Surgical capsuloraphy/Restitution of ligaments ?
Use of Mersilene or fascia lata around condylar neck ?
Internal Lateral pterygoid myotomy 15
External Lateral pterygoid myotomy 1
Open Condylotomy 4
Closed Condylotomy 2
To recreate mechanical obstruction along condylar
path
Anterior reposition/forward placement of disc ?
Downward and inward fracture of zygomatic bone ?
Eminoplasty with screws or L shaped pins 3
Eminoplasty with plates, mini-anchors 24
Eminoplasty with inlay bone grafts (Norman procedure) 4
Eminoplasty with onlay bone gafts (Dautery procedure) 60
To remove mechanical obstacle along condylar
path
Eminectomy (Standard) 95
Eminectomy (Modified) 1
Arthroscopic eminectomy 5
? (Questionable)-signify that the number of cases treated by the treatment
method could not be obtained.
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general anaesthesia, analgesic control with or without
sedation. Other methods that have been used in litera-
ture include the wrist-pivot technique by Lowery et al.
2004, [30] combined ipsilateral staggering technique by
Thomas et al. 2006, [97] the extraoral technique by
Chen et al. 2007 [43]. Awang et al.1987 [71] also
described the gag reflex procedure in which the soft
palate is rubbed across with a dental probe to initiate
relaxation of the lateral pterygoid muscle and sponta-
neous reduction and closure of the mouth. However,
Hippocratic maneuver still has the highest success rate.
Acute or chronic superior dislocation is better treated
by gap arthroplasty, the impacted condylar head in the
middle cranial fossa must be left in place to avoid bleed-
ing, cerebrospinal fluid leakage and infection [26,35,
52,64].
Condylectomy is done for prolonged type II (com-
plete/luxation) lateral dislocations, while treatment of
type I and early type II is achieved by closed reduction
of both dislocation and associated mandibular fractures,
and intermaxillary fixation using arch bars, stainless
steel ligature and tie wires for 4-6 weeks [9,61]. When
there is bilateral condylar extracapsular fracture, open
reduction and internal fixation of the condylar segment
is indicated in addition to intermaxillary fixation with
elastic bands for 2-4 weeks [8,9,61].
For chronic protracted dislocation, it is usually in the
proposed type III position, the Hippocratic maneuver is
usually unsuccessful without general anaesthesia and
muscle relaxants and even with that, failure rate is high.
Conservative methods like elastic rubber traction with
arch bars and ligature wires/IMF with elastic bands are
useful to achieve reduction in chronic protracted dislo-
cation. Prior to the use of elastic bands, acrylic blocks
or impression compound spacer can be placed in
between upper and lower teeth to depress the mandible
and open up the bite posteriorly, this helps displace the
condyle downwards, the elastic bands that are applied
front backwards helps to push the mandible/condyle
backwards into the fossa after removing the spacer in
about 72 hrs to 1 week. Extrusion of the teeth has been
reported and it is corrected with bite plane [15,103].
Bone hook has also been used to apply traction via
the sigmoid notch [15] Traction with wires is also pos-
sible through holes drilled in the angle of the mandible
[15].
Manual reduction under local anaesthesia/deep tem-
poral and masseteric nerve blocks [83], conscious seda-
tion and general anesthesia or have also been described
and these should be done first, but most cases are
mainly amenable to surgical procedures.
In 1981, Lewis et al. [84] used Bristow’s elevator to
push the condyle into position via the Gillie’s temporal
approach for zygomatic bone elevation, the incision was
extended to the preauricular region. This is the assisted
reduction under general anaesthesia.
When surgery is indicated for chronic protracted/pro-
longed dislocation (CPD) especially cases with longer
duration, the goal may be to reposition the condyle in
the glenoid fossa and restore movement; or if there is
movement in the new position, the goal will be to set
back the protruded mandible and correct occlusion.
When temporalis is short and spastic, Laskin proposed
an intraoral surgical approach to the muscle via a coro-
noid incision to do a temporalis myotomy [100]. Where
access is difficult, when there is fibrosis or adhesions of
muscle and cases where reunion of the muscles may
occur, coronoidotomy with or without condylotomy is
advocated [15].
Gotlieb advocated condylectomy and coronoidectomy
in cases where there is ankylosis but there is possibility
of entering the base of the skull and excessive bleeding
from pterygoid plexus, internal maxillary and middle
meningeal vessels [112].
Vertical and oblique ramus osteotomies have there-
fore, been described by many authors but these have the
disadvantages of less bone contact, and impingement/
impaction of the coronoid process on the condyle and
the new joint, causing restrictions of movement
[20,23,77,112,113].
Inverted L-shaped ramus osteotomy has been
described by Adekeye in 1976 [112] to ensure maximal
bone contact which is necessary for stability and healing.
Bilateral sagittal split technique offers a better out-
come for correction of occlusion because there is no
extraoral scar, risk of damage to inferior alveolar bundle
is reduced in experienced hands and there is improved
bone contact. Also, there is less post-operative bleeding
and swelling from muscular detachment [20,112].
Chronic recurrent dislocation can be approached by
conservative procedures of injecting sclerosing agents,
autologous blood or platelet rich plasma into the lax
pericapsular tissue and superior joint space weekly over
a period of 6 weeks, [11-13,65,113] the sclerosing agents
include sodium psyliate or sodium tetradecyl sulphate.
Other workers have injected steroids into and around
the capsule. The action of these injections is to induce
fibrosis.
Moore and Wood [73,99] as well as some other work-
ers have also injected Botulinium A toxin into the lat-
eral pterygoid muscle, it is a protein catalyst, which
prevents release of acetycholine at the neuromuscular
junction. It reversibly inactivate the protein that binds
synaptic vesicles with the cell membrane. This is parti-
cularly useful when chronic recurrent dislocation is due
to tardive dyskinesia and dystonias. It causes dysarthria,
nasal speech, nasal regurgitation, painful chewing and
swallowing, myasthenia gravis-like syndrome when it
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