Erosive arthritis is characterized by inflammation and pannus formation.
Pannus is actually an enlarging synovial tissue
which causes the erosions of the adjacent cartilage and bone
and this actually includes many different types of arthritis.
The most common forms of erosive arthritis include rheumatoid arthritis,
gout and psoriatic arthritis.
So rheumatoid arthritis is an inflammatory type of arthritis
and it's most commonly seen in younger females.
The hands are the most commonly affected and usually sometimes the only affected area.
It can cause joint space narrowing with subchondral changes
which are similar to that seen in osteoarthritis
and usually the DIP joints of the hand or the distal interphalangeal joints are spared.
So as you can see in this patient, this is the metacarpal phalangeal joint.
It's the one that's most affected and then the PIP joint or the proximal interphalangeal joint
can also be affected. It can cause periarticular osteoporosis
which we can see in this patient here where we have the PIP joint and surrounding it,
you have areas of lucency or osteoporosis.
It can result in soft tissue swelling and you can see erosions of the wrist
and the proximal joints of the hand.
It can also cause ulnar deviation or subluxation at the MCP joints
which we see in this patient here.
So this is the ulnar aspect of the hand and you can see that each of this MCP joints
we have deviation towards the side of the ulna.
Gout is caused by deposition of calcium urate crystals within the joint space.
You can actually have many years of gout prior to the actual visualization
of radiographic changes. This is most commonly seen in males
and it most commonly affects the first metatarsal phalangeal joint or the MTP joint.
So here we have a coned down radiograph of the foot and it shows you the left MTP joint here.
You can see that there are erosive changes at the MTP joint which is characteristic of gout.
We have juxta-articular erosions and the classic term that's used is overhanging edges,
so you have erosions that actually have edges that kinda hang over the joint space.
You can have tophi which are soft tissue collection of urate crystals
and rarely this calcifies, so often they might not be seen in radiographs.
In the elbow, it can actually cause olecranon bursitis.
Psoriatic arthritis is often associated with skin and nail changes.
Typically, it involves the DIP joints of the hands.
So this is an example of a patient with psoriatic arthritis.
You can see here these are called pencil in cup deformities
so you have narrowing of one of the bones while the other bone appears to form a cup
around the area of narrowing and this is very characteristic of psoriatic arthritis.
You can see that it commonly affects the DIP joints or the distal joints of the hand.
It can also cause juxta-articular erosions and it causes enthesophytes
or bony overgrowths at the site of tendon insertions.
Again, you can see this pencil in cup deformity
which is the classic description of a patient with psoriatic arthritis
and that's bony resorption of the terminal phalanges
with one phalanx protruding into the other.
So CPPD or Calcium Pyrophosphate Deposition Disease
is a mixed hypertrophic and erosive arthritis.
It's caused by depositon of calcium pyrophosphate dihydrate crystals
within the cartilage surrounding the joints
and it's often associated with chondrocalcinosis
which is calcification of the articular cartilage.
Imaging features make it difficult to distinguish from osteoarthritis.
It does have chondrocalcinosis which we'll take a look at
and the key feature is that it affects joints that are not typically affected by osteoarthritis,
so similar radiongraphic findings as osteoarthritis but in joints,
that you really wouldn't expect that to occur in.
You can also have pannus formation with CPPD.
So this is an example of chondrocalcinosis.
You have calcification of the articular cartilage which is pointed out by this arrow here.
This is commonly seen with arthritis in general and it's often asymptomatic
but it is one of the features of CPPD.
So this is an example of a patient with CPPD.
In the hand and wrist, it has typical findings of what are called hook shaped overgrowths
of the metacarpal heads and you have narrowing of the radiocarpal joint space
with widening of the scapholunate junction.
We'll take a better look at these findings in just a second.
This can actually result in scapholunate advance collapse or SLAC wrist
which we see here which is collapse of the capitate which is right here towards the radius.
So this is an example of the overhanging edges that you would see
and here as we said we have collapse of the capitate towards the radius
and you have narrowing of the radiocarpal joint space.
Here we have widening of the scapholunate junction.
So we have the scaphoid right here and we have the lunate here
and this junction here is wider than you would normally expect.