[The temporo-mandibular joint in pathologic conditions: rheumatoid arthritis and seronegative spondyloarthritis]

Pain and dysfunction of the temporomandibular joint (TMJ) are major clinical problems, especially in arthritides and allied conditions. In the last 10 years, such new imaging methods as arthrography, CT and MRI have been developed, but many problems are still to be solved. This study was aimed at reporting the radiographic patterns of lesions in TMJ rheumatoid arthritis and seronegative spondyloarthropathies and at investigating the role of conventional radiology in the assessment of these disorders. Digital hypocycloidal tomography of the TMJ was performed on 44 patients affected with rheumatoid arthritis, on 2 with Sjögren's syndrome, 2 with ankylosing spondylitis, 4 with psoriatic arthritis and 1 with Reiter's syndrome. CT, with sagittal and coronal scans, was performed only on 9 patients (18 joints) whose clinical and radiographic findings were particularly severe. The radiographic features of the lesions--i.e., erosions, osteophytes, subchondral bone sclerosis and condylar-glenoid fossa remodelling--cannot be distinguished from one another and from the so-called allied conditions; nevertheless, in rheumatoid arthritis abnormalities are usually bilateral and symmetric, whereas in seronegative arthropathies joint involvement is usually unilateral. In the first stage of the disease, these lesions are better demonstrated by CT than by tomography, thanks to better contrast and spatial resolution of the former, especially on the lateral and medial aspects of the joint. The most common findings were: erosions (68.2%), osteophytes (31.8%), subchondral bone sclerosis (28.6%) and condylar-glenoid fossa remodelling (9.1%). In the clinical practice sagittal multidirectional tomography remains today the method of choice because it can demonstrate several areas on the condylar surface, with finer anatomical detailing, and it can solve most diagnostic problems in TMJ disorders. Thus, CT is recommended only in the patients whose diagnosis remains questionable with the above techniques.