ATM DISLOCATIONS
1. Definition:
a. Contusion: this is damage to the joint equipment without bone damage; these lesions can affect the capsule, the interarticular ligaments and the meniscus in isolation or jointly.
b. Sprain: Traumatic injury to the joint corresponds to an elongation of the ligaments which can go as far as their partial or complete rupture. This injury does not cause a permanent loss of the normal relationships of a joint which differentiates it from dislocation in which the joint loses its normal relationships permanently.
4. X-ray:
The standard radiological assessment shows nothing.
MRI provides maximum information
5. Treatment:
These lesions are usually not serious:
– Prescription of painkillers and anti-inflammatories,
– The joint is rested: soft diet for a few days.
1.Definition:
It is the permanent loss of normal relationships of the articular surfaces,
This definition excludes spontaneously reducible displacement.
2. Etiology:
– TM dislocations can occur after forced mouth opening, an effort to yawn, more rarely, it can be the result of a burst of laughter or during oral-dental treatment (overly forceful maneuver)
– During an impact on the chin or the mandibular angle.
– Structural and morphological lesions, such as ligament weakening and occlusal dysfunctions.
3. Classification: There are 04 varieties:
Anterior dislocation: unilateral or bilateral
Posterior dislocation
Lateral dislocation
Superior dislocation.
a) Anterior dislocations:
The condylar head passes in front of the temporal eminence and cannot return to the glenoid cavity prevented by the protrusion of the temporal eminence and the contracture of the muscles. It can be unilateral or bilateral.
1. Etiology:
Circumstances of occurrence:
-Forced mouth opening: yawning, intubation, dental care, laughing, vomiting, taking fingerprints, digestive endoscopy.
-Shock on the chin, oriented from top to bottom.
Pathological causes: epileptic seizure,
Predisposing factors: ligamentous hyperlaxity, uncompensated tooth loss, abnormalities of the bone ends (flat condyle), menisco-condylar asynchronism
2.Clinic
: after forced opening of the mouth, the patient feels a clicking sound in the joint immediately followed by significant and permanent pain (it only subsides with reduction, hinders speech and swallowing (salivary incontinence)
Bilateral form: the patient presents:
-In blocked open mouth, but molars can touch
-Abundant salivation (inability to swallow)
-Dry throat
-Chin lowered, projected forward
– Hollow cheeks
-Palpation of the pretragal regions reveals emptiness of the glenoid cavities and perceives the condyles in front of the joints.
Unilateral form: The signs are more discreet
-The anterior gap is less important
-The chin is deviated to the healthy side (unlike a condylar fracture)
-The cheek on the dislocated side is flattened and tense, hollowed on the healthy side
3. The radio :
A dental panoramic scan confirms the diagnosis, revealing an empty glenoid cavity and a condyle in a very anterior position.
Arthrography and MRI show that the disc is located in front of the temporal eminence.
4. Treatment:
Treatment depends on the circumstances in which the dislocation is observed:
4.1 recent blocked dislocation:
easy to reduce by the NELATON maneuver, which most often does not require any anesthesia;
-The practitioner stands facing the patient.
-The 2 thumbs, previously wrapped in a protective compress, are introduced into the mouth and placed on the lower molars, while the other fingers of each hand encircle the angular region.
-The subject’s head is immobilized by an assistant
– First, a lowering movement must be performed to free the mandibular condyles blocked in front of the temporal eminence.
-In a second step, and by a retropulsion movement, put the condyles back in place
-This reduction can be done simultaneously or separately
- In a number of cases, this simple maneuver proves incapable of obtaining the reduction, it then becomes necessary to make the muscle spasm give way, anesthetic infiltration of the masticatory muscles may be sufficient, if the maneuver fails → indicate the indication of general anesthesia.
- After reduction:
-A control X-ray appears to be essential to check the reinsertion of the condyles at the level of the glenoid cavity.
-An elastic sling is placed to hold the mandible for a few days.
4.2. Irreducible dislocation: It is surgical
– The major obstacle to reduction is located at the level of the external lateral ligament which cannot be distended sufficiently to allow the lowering of the condyle, its section allows reduction.
-If the disc is torn, a discectomy should be considered, followed by the placement of an interposition.
4.3. Recurrent dislocations:
They are found in patients with bone dysmorphia or ligament hyperlaxity.
When recurrences become troublesome due to their frequency and the increasing difficulty of reduction maneuvers, the patient must be given special treatment:
-Occlusal treatment: necessary from the first consultation, it becomes essential in the event of relapses, it is most often sufficient to avoid them.
-Arthroscopy: it allows coagulation of the retro-discal tissues which acts by limiting disc play and condylar sliding.
-Surgery: consists of performing either:
- Precondylar stops: the principle of which is to place an obstacle in front of the temporal eminence to limit the anterior sliding of the condyle
- Discectomy,
- Myrhaug technique: removal of the temporal condyle in order to surgically create a perfectly reducible permanent subluxation.
- Condylectomy: removal of the condyle allows for mandibular retraction and pain relief but causes significant disturbances in mandibular kinetics
4.4 Old neglected dislocation:
Prolonged emptiness of the glenoid cavity leads to changes in the joint structures.
-Condylectomy.
– Eminencectomy: functional results, after restoration of occlusion and rehabilitation, appear better than those of condylectomy.
b) Posterior dislocations:
Clinic:
-Rare, they occur after a horizontal shock to the chin.
-The condyle is in the most posterior position, pushing down on the tympanic membrane.
-It is accompanied by otorrhagia, sometimes by hearing loss.
-The mouth opening is very limited, molar gap.
-On palpation, the mandibular condyles are inside the EACs.
The radio:
– CT scan confirms the tympanic membrane fracture.
Treatment :
-A reduction which will be carried out by the reverse NELATON maneuver (giving an anterior movement to the mandible so as to make the condyles come out of the CAE)
-A brief immobilization of the mandible.
-This will be followed by CAE processing.
c) upper dislocation:
Clinic:
-Exceptional and very serious, they occur after a very violent vertical shock
– Mouth open, the condyle sinking into the middle cerebral fossa
-The mouth opening is very limited from the outset
-The scan shows intracranial displacement of the condyle and fracture of the base of the skull.
Treatment :
After removing the vital risk, the reduction is orthopedic, rarely surgical . In the event of ankylosis, they involve a section of the condylar neck.
d) Lateral dislocation:
Clinic:
Exceptional: due to a dislocation outward on one side, and inward on the other side, internal on the side of the impact, external on the other
Often accompanied by condylar fracture, hence the importance of the X-ray
At the dental level, we note the existence of a lateral cross bite
Treatment:
the treatment is orthopedic