and translations, which load the corresponding joint surfaces more heavily during movements. In this way even compensated joint surface changes can be discovered early by provoking a painful response.
Crepitus is a primary examination parameter. The examiner must determine whether at any given moment during manipulation the rubbing sound occurs more loudly and distinctly than during nonmanipulated active movements (protrusion and opening). In addition it should be determined if there is any pain produced by compression. Whenever there are painful alterations in the joint surfaces, the endfeel of inferior traction and anterior translation must be tested before any conclusions are formed about the effectiveness of a possible unloading of the joint. The results of the tests of the joint surfaces allow the following deductions to be made:
• Adaptation: no crepitus and/or no pain during active movements and dynamic tests
• Compensation: crepitus and/or pain only during the dynamic tests
• Decompensation: crepitus and/or pain during active movements and during dynamic tests.
Manifestations of Joint Surface Changes
Unlike other synovial joints the temporomandibular joint has joint surfaces of fibrous cartilage, a highly differentiated connective tissue with no blood vessels or nerve endings. Compared with hyaline cartilage, fibrous cartilage is less easily deformed because of its higher fiber content (Gay and Miller 1978). The mucopolysaccharide content of the synovial fluid is responsible for lubrication of the joint surfaces (Smith 1982). This is why there are normally no noises or pain during active movements and during dynamically influenced movements.
• An increase of crepitus during dynamic compression in the absence of pain indicates osteoarthrosis, a regressively adapted, noninflammatory stage of joint surface damage.
• If crepitus and pain are both provoked there is osteoarthritis, an inflammatory stage of joint surface damage.
The examiner must make certain that the provoked pain is intensified by application of compression and not by a nonspecific joint loading due to increasing jaw opening.
164 A healthy joint
Left: Anatomical preparation of a right temporomandibular joint with the jaws closed. The rounded condyle is covered by a uniform layer of fibrous cartilage. There is no fibrous cartilage on the superior and posterior portions of the fossa. Only the posterior slope and the crest of the articular eminence exhibit functional joint surfaces.
Right: During jaw opening there are no grating sounds or pain.
165 Nonreducing anterior disk displacement
If the disk is displaced anteriorly when the mouth is closed, the top of the condyle will be covered by part of the overstretched bilaminar zone, which at this time acts as the articulating surface. The compression test will intensify pain in this area.
Right: As the jaws are opened, the condyle pushes the disk ahead of itself, thus increasing pain and limitation of movement.
166 Adaptation of the bilaminar zone after anterior disk displacement
Left: Dynamic compressions are associated with pain and limitation of movement only if the bi laminar zone has not adapted as seen in this MRI (light gray, arrows).
Right: This MRI shows an adapted (fibrosed) bilaminar zone as dark gray (arrows). Under the right circum stances dynamic compression will provoke no pain and the joint will require no treatment.
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
