A patient with internal derangement of the temporomandibular joint (TMJ) can be assigned to one of four stages based on the clinical findings.


Internal Derangement


disk displacement with reduction (reciprocal clicking)


disk displacement with reduction associated with intermittent locking


disk displacement without reduction (closed locking)


disk displacement with disk perforation



Stage 1:

(1) Clicking on movement begins suddenly, either spontaneously or after an injury. The noise may be loud and can be heard by others.

(2) There is a feeling of obstruction within the joint during movements until the click occurs.

(3) The mandible often deviates toward the affected side until the click occurs, then returns to midline afterwards.

(4) There is also a fainter click when closing the mouth (reciprocal click), which can be heard on auscultation of the affected joint..


Stage 2:

(1) Reciprocal clicking with intermittent locking occurs.

(2) There may be pain over the affected joint.

(3) There may be a feeling of obstruction to the opening within the joint.

(4) The joint may unlock spontaneously or after applying pressure over the affected joint.

(5) An increased frequency of clicking and intermittent locking with greater difficulty in unlocking indicate transition to Stage 3.


Stage 3:

(1) There is a limited opening of the mouth ("closed lock"), often to 27 mm or less.

(2) Opening may be associated with severe pain.

(3) The mandible deviates toward the affected side during opening and toward the opposite side during lateral movements.


Stage 4:

(1) The patient is able to increase mouth opening.

(2) There is an increased crepitus and noise within the joint during movements.

(3) It is often less painful than Stage 3.

To read more or access our algorithms and calculators, please log in or register.