Luxation of the Lower Jaw

By Dr. Vishaal Bhat on Wednesday, 28 November, 2007 with 0 comments

The mandibular joint facilitates complex movements of the lower jaw. It consists of the lower and upper parts, divided by the articular disc (discus articularis). The pit is located at fossa mandibularis near divergence of processus zygomaticus ossis temporalis. The head is a part of processus articularis of the lower jawbone. A ligamentous cartilage equilibrates incongruence of the joint surfaces which are covered with a cartilage as well. During the initial phase of mouth opening process, the head turns at the lower part of the joint at the disc pit; then during a continuing movement of the jaw the head shifts together with the disc to the upper part of the joint - from fossa mandibularis along the planum tuberculum forward to tuberculum articulare - which makes a solid obstacle to further movement out of the pit. The articular capsule together with ligaments complete the whole structure of the joint.

Mechanism of luxation.

If the head leaves the pit by shifting in front of tuberculum articulare, the lower jaw luxation appears. Luxation without a bone damage happens at excessive mouth opening (yawning, screaming, cramps, vomiting), or during a forceful passive mouth opening (medical treatments: intubation, insertion of probe etc.). Recurring luxations appear at predisposed individuals (shallow tuberculum, loose articular capsule). Traumatic luxations happen upon forceful effects on the lower jaw’s edge (a hit, rarely after falling).

Classification of luxations.

  • acute luxations at the ventral direction (with no bone damage)

  • recurring luxations at the ventral direction (habitual luxations)

  • traumatic central luxations, happen by penetration of the mandibular condyle through damaged glenoid fossa into the middle cranial space (intracranial hemorrhage)

  • traumatic luxations at medial or lateral directions (extremely rare, mostly appear as luxation fractures of processus articularis mandibulae)

Manifestations and examination.

The basic sign is a patient’s mouth open that cannot be closed. Pain and tension are felt in chewing muscles and the mandibular joint. Saliva may leak from the mouth, since swallowing is difficult. During attempts to close the mouth, a resistance of tight chewing muscles can be felt. An empty pit of the mandibular joint can be felt upon palpation through the auditory canal. X-ray images show the head’s position in front of tuberculum articulare.

Therapy for the lower jaw luxations.

Timely repositioning of luxated lower jaw is crucial for a feasibility to use a simple maneuver. Soon, a spasm of chewing muscles causes a very strong resistance that can be surpassed under general anesthesia and after muscular relaxation only.

Repositioning can be commonly made by the Hippocratus grip: fingers of both hands embrace the lower jaw body with thumbs laid on the lower molars. By pushing thumbs downwards, the chewing muscles resistance is overridden and by pushing against the chin by rest of fingers, the head is placed into the fovea.

After a successful repositioning the jaw should be fixed by an external sling bandage or a simple wire intermaxillar bond for several days. A patient has to receive soft foods and be aware of wide mouth opening.

Opening of the mouth is then slowly rehabilitated; a physical therapy or muscular spasmolytics can be used. Recurring or habitual luxations require a surgical treatment that adjusts the joint path and removes obstacles (ablation of tuberculum articulare).

Category: Oro-Maxillo Facial Surgery Notes



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