WHERE IS THIS JOINT?
TMJ or the chewing joint is the joint situated right starting of the cheek bones. It is the joint that connects the jawbone to the skull. It is sliding hinge type of joint, so small yet so important that our very basic living depends on it.
WHAT IS ITS FUNCTION?
Chewing is the most obvious function. It allows the mouth to open and close during conversation and chewing. Helps perform different day o day activities associated with mouth. It is a very complex joint with many small complex movements that we take for granted.
WHAT COULD GO WRONG WITH IT?
TMJ disorders could occur internal within the joint or it could be external outside the joint.
TMJ Disorder (INTERNAL JOINT PROBLEM)
1- INFLAMMATION : This could be as a result of a direct hit , such as a hit to the chin or jaw or an indirect trauma , such as injury to whiplash , excessive chewing , scratching (bruxism) , jaw clenching or dental height loss due to worn or missing teeth.
A-Synovitis – It is the inflammation of the greasing liquid or the capsule. Pressure at rest and a small range or pain at the end of the range are often present.
B-Retro-discitis-The Retro-disc tissue (The joint disc’s posterior connection to the Mandibular fossa which is the jawbone) is rich in vascularity and innervation and may cause extreme pain if it is inflamed. At rest and with an opening, the jaw can go away from painful side.
2- INTERNAL DERANGEMENT: Internal derangement determines situations where structural changes within the joint occur. Direct trauma, such as blow to the jaw or fall on the chin, indirect trauma, such as whiplash damage, long term clenching or grinding, intense or rough chewing , or prolonged periods of opening of the mouth , such as dental surgery or general anaesthetic, may cause it.
A-Disc displacement WITH reduction – The articular disc (the disc that is present between the joint) can be displaced in either direction, but will be displaced anteriorly (front) more often. During the opening, the disc is forced forward and bunched up. The disc will reposition or reduce itself at a certain point in the range, creating an audible click. Sometimes the jaw will deviate from the side affected.
B-Disc displacement WITHOUT reduction– The disc will not reduce pain and loss of range in this more severe version. This is regarded as a closed lock. Sometimes the jaw will deviate from the side affected. There will be no click, but the patient may report that at the time when their jaw locked, there was a click.
3- ARTHRITIS: In the TMJ, degenerative Arthritis may occur. TMD friction voice or crepitus can also be felt or with a stethoscope, can be heard. Joint degeneration is either due to age, or secondary due to a trauma that happens at a younger age. TMJ, like any other joint can be affected by rheumatoid arthritis, AK, infectious arthritis, Reiter syndrome and gout.
4-JOINT HYPERMOBILITY: Excessive anterior or front motion of the jaw and the articular disc results from hypermobility at the TMJ. This would lead to a deviation of the jaw away from the side affected. TMJ usually has some clicking sounds. It may or may not be present or cause discomfort. Hypermobility can also be associated with connective tissue disorders such as Marfan syndrome or other conditions such as Cerebral Palsy and Down Syndrome.
Long-term hypermobility can cause elongation and degeneration of the articular disc. On closing the jaw, the disc can then fail to come back to its position, causing the TMJ to become Trapped in an open position (open lock). This can also happen when opening the mouth widely in activities, such as singing, yawning or after a lengthy dental operation.
TMJ DISORDER Extra-articular causes (outside the joint):
1: MUSCLE SPASMS: Muscle spasms can cause intense pain and hinder the movement of the jaw. This is known as Trismus. It often affects one or more muscles, most commonly the mastication muscles, especially the muscle masseter, temporalis and pterygoid. Causes include prolonged dental procedures or anaesthetics where for extended periods of time the mouth has been held open , stress , bruxism and postural dysfunction.
2: CERVICAL POSTURAL DISORDERS: It can produce pain in the jaw. The reason being is simple, it disturbs the natural positions of the muscle attachments that leads to over stretching. When the chin is poking outwards it creates a backward force on the jaw and the joint disc. Poor posture or stress related posture, eventually will cause swelling, pain and gradual disc degeneration.
3: TEMPORAL TENDINOPATHY: This is caused, typically as a result of bruxism, by excessive contraction of the temporalis muscle. The anterior part of the temporalis tendon, palpable just above the zygomatic arch (cheek bone), has tenderness and swelling. There may also be tenderness of the temporalis tendon where the coronoid process is inserted. It is palpable when the jaw is slightly open just below the zygomatic arch (cheek bone).
4: TRAUMA: The mandibular symphysis or the condylar neck also cause fractures of the mandible. A blow to the jaw or fall on the chin can be the mechanism for injury. In order to begin early mobilization of the TMJ and restore function, care will typically begin within a week or two of surgery.
SYMPTOMS OF TM JOINT DYSFUNCTION:
-TMJ headaches (headache around temples)
-TM JOINT pain
-Clicking sound while chewing
-Difficulty in opening the mouth fully
-Locking of the jaw.
The examination will include the posture especially the cervical, palpation of the TMJ to assess one or both TMJ for swelling , Muscle spasm and stiffness or joint hypermobility, assessment of the range and quality of motion of the jaw and neck noting any deviation or deflection of the jaw .Signs for bruxism is also checked.
Even though the symptoms are long standing and severe, physiotherapy is very successful in relieving and controlling TMD. With adequate physiotherapy, within 3 to 6 weeks, most patients will see a noticeable change in their symptoms. Physiotherapy in the short term and long-term cure TMJ and in most cases permanently.
If the symptoms are acute and inflammatory, the condition is likely to be irritable, so the treatment approach is very gentle to relief the pain, swelling and muscle spasm. After that range of motion and alignment of the jaw is focused. Treatment can include TMJ massage, soft tissue releases, joint mobilisation, acupuncture techniques. Along with it there is posture correction of the head, neck and shoulders and any associated pathologies with cervical region. The patient is taught TMJ exercises to reinforce balance, stability and alignment of the jaw.
Activities Such as chin resting on the hand , pencil chewing , jaw clenching while awake ,big mouth yawning , nail biting , chewy snacks , chewing gum, eating foods such as large hamburgers and hard foods such as apples and nuts should be avoided especially during rehab .
This includes several Procedures:
-Arthroscopy, which is view the joint to reposition the disc, remove any scar tissues.
-Arthroplasty or Arthrotomy which is removal of any growths and disc surgery.
-Arthrocentesis which is injecting lubricating fluid in the joint to reduce TMJ friction
– Joint replacement which is basically Jaw joint replacement.
TMJ surgery is indicated when it is:
– Recurrent dislocation
– Developmental disorder
After Surgery, it is imperative that patient goes thru physio rehab in order to avoid scar tissue adhesions, regain full range of motion and activities of the mouth.