Joint sounds

There are 2 types of joint sound to look out for:

• Clicks - single explosive noise• Crepitus - continuos 'grating' noise

Clicks

A joint click probably represents the sudden distraction of 2 wet surfaces, symptomatic of some kind of disc displacement. The diagnosis of a joint click, and therefore treatment, varies on whether the click is left, right or bilateral, painful or painless, consistent or intermittent. The timing of a click is also significant: a click heard later in the opening cycle may represent a greater degree of disc displacement.

Clicks may frequently be felt as well as heard, though they are not normally painful.

Crepitus

Crepitus is the continuous noise during movement of the joint, caused by the articulatory surfaces of the joint being worn. This occurs most commonly in patients with degenerative joint disease.

The joint sounds should be listened to with a stethoscope, preferably a stereo one, as the two sides can be more easily compared.

Range of motion

This is the only truly measurable parameter, as the others are more subjective. It is just as important to record jaw movement as a means to assess the rate and degree of improvement as it is to determine the severity of symptoms.

Movements to be measured are:

• Incisal opening - pain free limit• Incisal opening - maximum (forced)• Lateral mandibular excursions• Mandible deviations on pathway of opening

Incisal opening

The incisal opening is measured from the upper incisal tip to the lower, with the patient first of all opening to the limit of their comfortable, pain free range. This is then compared to the normal range of motion(see right). Their maximum (forced) limit is also recorded. It is important to determine whether a limitation of vertical movement is due to pain or a physical obstruction. If it is pain, then it may be a muscular problem, if an obstruction, then disc displacement is most likely.

Lateral Excursions

The lateral movement should be measured from mid-line to mid-line, the patient moving the mandible to their maximum extent, from one side to the other.

Mandibular deviation

When the jaw is opened, the path it follows should of course be straight and consistent. Deviations from the norm are either lasting or transient, and are all suggestive of internal derangements of different sorts.

Lasting deviations

Lasting deviations are caused by the joint on one side not moving as far as on the other. If the movement is consistent but off centre(i.e. a straight diagonal pathway), this may due to adhesions within the joint. If the movement is normal till just before the maximum range, when a lateral deviation occurs, this may be due to anterior disc displacement without reduction (if the overall range of opening is reduced).

Jaw closed Jaw opened

Transient deviations

Transient deviations occur when the joints are moving as far but at different rates. This is often caused by disc displacement with reduction.

Medial or Lateral Pole? Occlusion/TMD

Sep152011

I’m not sure of the exact percentage of patients that have a “pop” or “click”,

but joint noise is a common finding. When working with a patient that has joint noise my

primary concern is to assess the stability of the joint. If the situation is unstable or the patient

is symptomatic relative to the joint, then together we determine the appropriate treatment to

try to establish an asymptomatic, stable condition. Other patients who come to see me with

joint sounds are asymptomatic, and from my examination have a stable joint. The next

question I ask myself, especially if they have restorative concerns, is “what is the risk of

altering that stability”?

Checking for Palpable Sounds

Regardless of whether I am trying to answer the question of stability, or determine a course

of treatment, one question must be answered, where is the disc? A more accurate way to

ask the question is really, “Where is the disc off?” There are only two choices, medial pole or

lateral pole, but knowing the answer is a key piece of information. Taking a thorough history

is an important piece of understanding the health and stability of the joint, and begins to point

us towards our answer. The definitive answer comes from analyzing the joint sounds and

determining whether they occur in rotation or translation. When the temporomandibular joint

is seated the load from the muscles is delivered through the medial aspect of the head of the

condyle and disc. This load remains on the medial aspect during rotation and begins to move

laterally as the joint opens further and begins to translate. Rotation occurs during

approximately the first 1/2 inch (12mm) of opening, after that the joint is translating until it

reaches maximum opening, and then the process reverses. During lateral excursions, the

working joint (right lateral the right joint) is rotating and the non-working or balancing side is

translating.

Doppler Auscultation

With this ability to differentiate when rotation is occurring versus translation, all we have to do

is record during which movement the noise occurs. If the pop, click or crepitus occurs during

rotation, the disc is displaced on the medial. If the noises occur after translation has begun,

the displacement is at the lateral aspect. Pops and clicks can often be detected with joint

palpation and this is always part of my exam, but in order to not miss crepitus or noise that

isn’t palpable I auscultate. thedoppler will pick up noise and let me easily differentiate when it

is occurring rotation (medial) or translation ( lateral), it also allows the patient to hear the

noises and get curious about what it means.