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”?
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.
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. the doppler 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.