Degenerative Joint Disease (Arthrosis, Osteoarthritis)
‘DJD 1ncludes a •variety of anatomic findings, including irregular, ‘perforated, or severely damaged disks in association with articular surface abnormalities, such as articular surface flattening, erosions, or osteophyte formation (Fig:
30-14). The mechanisms of TMJ degenerative diseases are not clearly understood but are thought to be multifactorial. Current concepts of DJD incorporate three possible mechanisms of injury: (1) direct mechanical trauma, (2) hypoxia,reperfusiori injury, and (3) neurogenic inflammation. I I
Mechanical trauma may be a result of significant and obvious trauma to the joint or much less obvious microtrauma, such as excessive mechanical loading. The excessive stress produced in the joint can lead to molecular disruption and the generation of free radicals, with resulting oxidative stress and intracellular damage. Excess loading can also affect local cell populations and reduce the reparative capacity of the joint .It must be emphasized that it is impossible to predict the progression of joint pathology. .Patients with DJD frequently experience pain associated with clickmg or crepitus, located directly over the TMJ. Usually, an obvious limitation of opening is present, and symptoms’ usually increase with function. Radiographicfindings are variable but generally exhibit decreased joint space, surface efosions, osteophytes, and flattening of the condylar head. Irregularities in the fossa and articular eminence. may also be resent.