In contrast with other definitions (Stegenga 1991), osteoarthritis is not a joint surface lesion with inflammation of the surrounding soft tissues, but rather a destruction of fibrous cartilage with painful exposed subchondral bone.
Osteoarthrosis and osteoarthritis can occur with or without disk displacement and, as previously stated, may accompany disk perforation. It cannot be differentiated clinically for each individual case, but this is not relevant to the treatment.
Nonreducing disk displacement represents a special case. If under dynamic compression there is no crepitus but pain and limitation of the jaw-opening movement, capsulitis of the bilaminar zone with nonreducing disk displacement should be suspected. In this situation the disk is anteriorly displaced and no repositioning occurs during jaw opening. A portion of the overstretched bilaminar zone lies over the top of the condyle. If this portion has not become adapted through fibrosis, it produces pain that is increased by dynamic compression. Protrusion or jaw opening will further increase the pain so that the clinical appearance of restricted jaw opening results. The clinical presumptive diagnosis can be reinforced through passive superior compressions and, if necessary, verified by imaging procedures.
167 Perforation of the articular disk
Left: For diagnostic and therapeutic purposes, a disk perforation is regarded as a change in the temporal or the condylar joint surfaces. This type of joint surface damage usually has an anterosuperior loading vector. Treatment is always directed in the direction opposite the loading vector regardless of morphological relationships.
Right: For this reason, arthrography is not indicated for disk perforations
168 Osteoarthrosis/osteoarthritis and disk perforation
Left: Disk perforations in combination with degenerative changes in the joint surfaces occur frequently in the center of the disk or in the bilaminar zone.
Right: During jaw opening under compression there will be intensified rubbing sounds, possibly accompanied by increased pain. In many cases the disk perforation (blue) cannot be satisfactorily diagnosed. However, this is not necessary for treatment purposes.
169 Osteoarthrosis/osteoarthritis and disk displacement
Left: Condyles with degenerative changes can exhibit many different forms. In a few cases like this the areas of bone damage are not associated with significant changes in position and shape of the disk (arrows).
Right: Severely deformed joints, however, are usually accompanied by disk displacement (arrows) or perforation. Regardless of the position of the disk, the inferior surfaces of disks are affected by degenerative changes almost three times as frequently (57%) as the superior surfaces (Kondoh et al. 1998).
Conducting the Clinical Joint Surface Tests
Testing of the functional joint surfaces on the patient begins with active movements. For this the examiner, while either standing or sitting at the 12 o’clock position, places two fingers over each condyle and then instructs the patient to first protrude the lower jaw as far as possible and then make a maximal jaw-opening movement from the protruded position. During these movements both examiner and patient remain alert to any isolated grating sounds or grating sounds in combination with pain. As a rule, crepitus during protrusion comes from the temporal joint surfaces and crepitus during jaw opening from the condylar surfaces.
These active movements serve as a base of reference for the following tests.
For the dynamic compression test, the examiner places two or three fingers under the angle of the mandible on each side so that neither the facial blood vessels nor the medial pterygoid muscles are significantly disturbed. The examiner now exerts a superior or anterosuperior pressure while the patient again protrudes and then opens to the maximum. Under physiological conditions, neither rubbing sounds nor pain will occur during the movements.
170 Active protrusion followed by jaw opening
Left: Active movements serve as a reference (control) for the dynamic tests. As the examiner palpates the condyles, the patient executes a maximal protrusive movement
Right: From the position of maximal protrusion the jaws are then opened to the maximum. Both the examiner and the patient remain alert to any rubbing sensations that may arise, either with or without pain.
171 Positioning the middle and ring fingers at the angle of the jaw for performing dynamic compressions
Left: For dynamic compression two or three fingers are placed under the horizontal part of the angle of the mandible in such a way that the facial blood vessels and the insertion of the medial pterygoid muscle will be compressed as little as possible.
Right: Enlarged view showing the finger position at the angle of the jaw in greater detail.
172 Dynamic compression during protrusive and opening movement
Left: As the examiner presses superiorly or anterosuperiorly, the patient pushes the lower jaw forward as far as possible. Rubbing sounds that occur now usually arise from the temporal surface of the joint.
Right: Next, as the upward pressure is maintained, the patient opens the jaw as far as possible. Crepitus, pain, and any restrictions of movement that occur are recorded to help in making a differential diagnosis
Crepitus during the protrusive movement indicates osteoarthrotic changes in the temporal joint surface, while crepitus during the opening movement points to changes on the condyle.
If dynamic compression provokes crepitus with pain (osteoarthritis) or crepitus without pain (osteoarthrosis), the examination is continued with dynamic translations. These can be conducted with or without manual compression. In this section of the book dynamic translation without compression is depicted, while the technique with the addition of compression can be seen on page 105.
Dynamic translations in the lateral and medial directions are specific for evaluating the lateral and medial portions of the joint surfaces. This is especially important when there is incongruence of the joint surfaces in the frontal plane. The parameters that can be distinguished by the dynamic tests are summarized below.
• Osteoarthosis vs. osteoarthritis: the tests either proceed painlessly or they elicit pain
• Temporal vs. condylar: symptoms appear either during protrusion or during jaw opening
• Lateral vs. medial: symptoms appear either during lateral or during medial translation.
173 Hand position for dynamic translations
Left: To stabilize the head, one hand is placed flat against the back of the patient’s neck. This also stabilizes the cervical spine. The thumb is placed at the level of the angle of the mandible.
Right: The other hand