Introduction to Arthritis
When an arthritic process is well established in a particular
patient, it will usually achieve a typical appearance, which
allows diagnosis by means of imaging. At such a moderately
early or mid stage of disease, radiographs are usually sufficient
to make the correct diagnosis. The diagnosis usually depends
on the location of the joint abnormalities and a host of other
radiographic characteristics.
Location of involved joints can often eliminate some
diagnoses and raise the probability of others. For example,
distal interphalangeal joint disease is commonly seen in
psoriatic arthritis, osteoarthritis, and erosive osteoarthritis.
However, it is not seen in rheumatoid arthritis until extremely
late in the disease; thus RA should not be considered in an
early arthritis. Similarly, a disease involving the sacroiliac joints
would raise the possibility of ankylosing spondylitis,
inflammatory bowel disease arthritis, psoriatic
spondyloarthropathy, chronic reactive arthritis, osteoarthritis,
and DISH. Common locations of joint involvement are
illustrated in diagrammatic fashion in this section. Note the
joints that are involved earliest and most commonly are
distinguished from those involved less frequently or in end-
stage disease.
While the location of the joints involved certainly contributes
to establishing a list of reasonable diagnoses, the lists can be
relatively long, as in the examples above. There are several
other parameters that are useful in honing that list to a single
diagnosis that are outlined in the tables that follow. Further
explanation regarding some of these parameters may be
helpful, as follows.
Age and gender may be the easiest parameters to apply.
There are a minimal number of arthritic processes that affect
children (juvenile inflammatory arthritis, hemophilic
arthropathy, inflammatory bowel disease arthropathy, and
septic joint) and teenagers (in addition to those affecting
children, early onset adult rheumatoid arthritis and ankylosing
spondylitis). Some diseases are gender specific (hemophilic
arthropathy and hemochromatosis), while others are found in
one gender far more frequently (gout, ankylosing spondylitis,
chronic reactive arthritis in males, and rheumatoid arthritis in
females).
One of the most important parameters is the character of the
process. Some arthritides are purely erosive; rheumatoid
arthritis is the hallmark for this group. Others are purely
bone-forming (also termed "productive"). This bone
formation may appear in the form of osteophytes (as in
osteoarthritis), enthesopathy or ligamentous ossification (as in
ankylosing spondylitis, DISH, and OPLL), or periositis (as in
psoriatic arthritis, chronic reactive arthritis, and juvenile
idiopathic arthritis). Other processes may be mixed,
sometimes starting with erosions but progressing to
osteophytes (as in pyrophosphate arthropathy or gout) or
starting with periostitis and progressing to mixed erosions and
osteophytes (as in psoriatic arthritis or chronic reactive
arthritis). These processes tend to be distinctive for each type
of arthritis by the time they are well established; between
evaluating the character of the process and its primary
location in an individual, the diagnosis can usually be secured.
Bilateral symmetry of an arthritic process can be a useful
characteristic. Rheumatoid arthritis is especially well known
for appearing bilaterally symmetric.
Good
ReplyDelete