Definition
Chronic progressive systemic inflammatory disease in which joints
are primary target
IMAGING
• Purely erosive arthropathy
• Uniform cartilage narrowing
• Osteoporosis
• Glenohumeral joint
○ Uniform cartilage narrowing
○ Erosions
Largest and
earliest at margin (junction of cartilage covered humeral head and greater
tuberosity)
Eventually,
erosions uniformly involve humeral head and glenoid
End-stage
destruction of entire head and glenoid
○ Subchondral cysts may be large, but underlying osteoporosis may
mask their size
○ Elevation of humeral head due to RCT With chronicity, head
seems to articulate with underside of acromion, molding acromion into
concavity
○ Hatchet-like mechanical erosion at medial surgical neck of
humerus
Due to chronic
elevation of humeral head and consequent rubbing of osteoporotic humeral neck against
inferior glenoid
Increases risk
of insufficiency fracture across surgical neck
○ Swelling of joint may be prominent due to decompression of
synovial fluid through RCT into subacromial/subdeltoid bursa
• Elbow joint
○ Effusion (elevated anterior and posterior fat pads)
○ Swelling about joint
Over olecranon:
Olecranon bursitis common in RA
Elsewhere due to
decompression of synovial fluid through capsule or into bicipital radial bursa
○ Erosions uniform throughout joint
Equally
involving capitellum, trochlea, ulna, radial head/neck
– End-stage uniform destruction of osseous structures
• MR in RA
○ Thickened, low signal, avidly enhancing pannus and synovium
○ Low signal rice bodies within effusion
○ Subchondral marrow edema
○ RCT, partial or complete
○ Decompression of synovial effusion well seen
DIAGNOSTIC CHECKLIST
• Other causes of synovitis, especially infection if Monoarticular
AP radiograph shows erosions of the distal end of the clavicle as well as at the coracoclavicular ligament insertion site of
the clavicle , typical sites of erosions in rheumatoid arthritis (RA).
Coronal graphic shows advanced RA of the shoulder. Thickened
synovium lining the capsule is distended by effusion. Cartilage is thinned uniformly.
Large marginal erosions are seen where bone is not covered by cartilage, and
smaller subchondral erosions are present. Marrow edema and rotator cuff tear complete
the picture.
Axial bone CT demonstrates the typical uniform glenohumeral cartilage
loss that is seen in RA, along
with humeral head erosions and subchondral cysts.
Coronal bone CT shows marginal erosion at the humeral head .
The head is subluxated superiorly secondary to chronic rotator cuff tear. This
results in a mechanical erosion of the osteoporotic bone at the surgical neck
of the humerus ; this puts the patient at additional
risk of fracture.
AP radiograph shows a case of severe, long-term RA, with
erosions of the clavicle, glenoid, and humeral head.
Coronal PD FS MR shows the retracted infraspinatus tendon , part of the chronic rotator cuff tear that is usually seen
with advanced RA. There is mild edema in the humeral head. The glenohumeral
joint is distended, and low signal synovitis fills the axillary bursa and extends across the rotator cuff tear into the subacromial
bursa . Note the humeral head elevation.
Coronal T1WI MR shows typical findings of RA in the shoulder.
There are low signal subchondral cysts, as well as a marginal erosion of the humeral
head .
Axial PD FSE FS MR in the same patient shows subchondral cysts
as well as a marginal erosion .
Note the thin and disrupted subscapularis tendon , with fluid seen both in
the glenohumeral joint and subdeltoid bursa. It seems remarkable that the radiograph
in this case appeared normal.
AP radiograph in a patient with RA shows only osteopenia and a
small marginal erosion . The osteopenia seen on radiographs
in patients with RA often disguises the full extent of erosive disease and subchondral
cysts.
Coronal T2WI FS MR in the same patient shows tremendous
synovitis in both the glenohumeral joint and subacromial/subdeltoid bursa . The diffuse nodular low signal
masses within the fluid are synovitis.
Sagittal T2WI FS MR in the same patient emphasizes the
tremendous synovitis in both the glenohumeral joint and subacromial/subdeltoid bursa
. Both the synovitis and extent of subchondral cysts extending
down the marrow are well depicted.
Axial PD FS MR in the same patient shows the size of the erosions
. It is quite remarkable that the radiographs showed only osteopenia
and a small erosion, even in retrospect. This humeral metadiaphysis is at risk
for fracture.
Coronal T1 FS postcontrast MR in the same patient confirms that
the marrow abnormality represents erosions and subchondral cysts, with low signal
fluid surrounded by enhancing synovitis . A rotator cuff tear is seen as well, with retraction of supraspinatus
.
Lateral radiograph of the elbow shows diffuse osteopenia and
soft tissue swelling over the olecranon . The location is typical for olecranon bursitis, secondary to
RA in this case.
Anteroposterior radiograph shows a classic case of severe and
long-term RA. There is symmetric erosive disease of the distal humerus, proximal
radius, and proximal ulna, along with osteopenia.
Lateral radiograph confirms the erosions, as well as a mechanical
erosion at the proximal shaft of the ulna where the remnant of radial head has been rubbing. The symmetry
of the process and purely erosive nature make the diagnosis RA.
AP radiograph shows extensive uniform thinning of cartilage
throughout the elbow and subchondral erosions at the coronoid . There is
extensive soft tissue swelling and diffuse osteopenia. No productive change is seen; the findings are typical
of RA.
Sagittal T2FS MR in the same case of RA shows complete loss of
cartilage and thinning of cortex at the capitellum . The fluid is all
contained within an extremely distended joint and contains low signal material that has been termed rice
bodies.
AP radiograph shows a lateral soft tissue mass but no other
abnormalities in a patient with RA.
Axial PD FS MR performed to evaluate the soft tissue mass in the
same patient shows synovitis and fluid surrounding the radial neck. There is a
thin neck of fluid extending from the joint
effusion to the mass . This proves that the mass is simply fluid from the joint,
which has decompressed into the soft tissues laterally, as happens in
restricted joints with active synovitis.
Sagittal T2WI MR shows bicipital radial bursitis related to RA.
Lobular-enhancing synovitis is seen in the bicipital radial bursa around the biceps tendon . Fluid and synovitis are
also seen in the elbow joint .
Sagittal T2WI MR in a patient with RA shows joint destruction, large effusion, and abnormal bone marrow signal . These findings could be due simply to advanced RA, but infection must be considered and was proved surgically.