Inflammatory Arthropathies: Beyond Rheumatoid
Arthritis affects more than 1 in 4 adults in the US, and is the most common cause of work disability. More than 100 types of arthritis have been described. Inflammatory arthritis is a group of arthritides characterized by inflammation of the joints, and often additional systemic manifestations. Diagnosing these diseases is based on clinical, imaging, and pathologic information, and is generally left to the patient’s primary care physician or rheumatologist. The role of the radiologist is to aid in the diagnosis, by identifying the presence or absence of imaging features characteristic for certain diseases.
1. Inflammatory arthropathies are commonly encountered in radiology. This exhibit will review the patient demographics, clinical presentation, and imaging features of these diseases.
2. Imaging features classically associated with specific inflammatory arthropathies will be discussed.
3. Radiography is the standard modality used in imaging these diseases, with MRI and ultrasound providing further characterization in certain cases. The reader will become familiar with the utility of different imaging modalities in the evaluation of inflammatory arthropathies.
Rheumatoid Arthritis (RA)
Chronic autoimmune disease affecting joints and synovial tissues
Adult onset, with peak in the 4th and 5th decades
2-3x more common in females
Symmetric, proximal joints of hands and wrists, then feet and large joints
MCPs and PIPs in the hands
Ulnar styloid and triquetrum in the wrist
5th MTP in the foot
Erosions are intraarticular
No sclerosis around the margins of erosions (as opposed to gout)
Imaging ideally can make the diagnosis prior to the development of extensive erosions
MRI and US are more sensitive than radiography in detecting early inflammatory joint processes
MRI- Bone edema and synovial enhancement can be seen prior to erosions
MRI- Erosions can be seen earlier than radiographs (by approximately 2 years)
US- Active synovitis with thickening and hyperemia
Psoriatic Arthritis (PsA)
A seronegative spondyloarthritis in patients with psoriasis
Usually about 10 years after onset of psoriasis
In 15% of cases, arthritis precedes skin lesions
4th and 5th decades, men=women
Finger joints are usually the first affected, as in RA
Can be difficult to differentiate from RA, even clinically
As in RA, can have synovitis, marrow edema, cysts, tenosynovitis affecting the radiocarpal, midcarpal, CMC, and MCP joints
PsA can be distinguished from RA by the presence of periostitis and dactylitis. Later stage PsA may have tuft erosions, pencil-in-cup deformity, and ankylosis
PIPs, DIPs affected more often in PsA than RA
One study showed that many patients with psoriasis and without clinically evident arthritis had MRI findings suggestive of PsA, particularly synovitis and periarticular edema
Most common inflammatory arthritis in men > 40
Peak onset 4th-6th decades
Male:female ratio is approximately 20:1
Most often be due to impaired uric acid excretion by the kidneys. Overproduction of uric acid is the cause in approximately 10% of cases
Stages include asymptomatic hyperuricemia, acute gouty arthritis, and chronic tophaceous gout
Most often affects foot, in particular the 1st MTP (podagra).
Can also be seen in hands/wrists, elbow, knee
Radiographic changes typically not present for 6-8 years
In acute phase, only periarticular soft tissue swelling may be seen
Many patients with gout and normal radiographs have occult destructive arthropathy, which can be detected on MRI or US
Findings include early bone erosions and synovial pannus
Chronic gout is characterized by tophi, “punched out” erosions with overhanging cortex and sclerotic margins, normal bone mineralization, and preservation of joint spaces
Calcium Pyrophosphate Deposition Disease (CPPD)
Calcium pyrophosphate dihydrate crystals deposit in connective tissues, which can cause chondrocalcinosis
May be asymptomatic, or cause acute or chronic inflammatory arthritis
Mostly age 60 or older. Approximately 50% of those 85 or older have CPPD
Slightly more common in women
Typically affects the TFCC, pubic symphysis, knee, and atlantoaxial joint
Characterized by linear chondrocalcinosis on radiography
Difficult to appreciate on MRI
On US, chondrocalcinosis can be seen hyperechoic areas within the hyaline cartilage
Can have large subchondral cysts, with or without osteophytes
Dual energy CT may be used to differentiate between CPP crystals and monosodium urate of gout
CPPD lacks the soft tissue masses characteristic of chronic gout
Crowned dens syndrome- CPPD in ligaments around the odontoid process
Erosive Osteoarthritis (EOA)
Typically presents in ages 60 or older
Female:male ratio of 12:1
Mostly affects the hands and wrists, particularly the DIP, PIP, 1st CMC, and trapeziometacarpal joints
Relative sparing of MCP joints can help differentiate from RA
With foot involvement, can affect the 1st MTP
Destruction of articular cartilage with erosion of the subchondral cortex
Characteristic “gull wing” appearance, due to central erosions of the more proximal phalanx combined with peripheral erosions of the more distal phalanx
This may be due to the fact that the articular cartilage on the proximal side is thinnest centrally, while the distal side is normally thinnest at the periphery
Notably absent are marginal erosions, extensive soft tissue swelling, and osteopenia
Advanced stages can result in IP ankylosis, as in end-stage PsA
Ankylosing Spondylitis (AS)
The most common seronegative spondyloarthritis
Usually presents in young adulthood, most commonly in the 3rd decade
Male:female ratio is 3:1
HLA-B27 is positive in more than 90% of patients
Sacroiliitis is usually the first manifestation, followed by spine involvement
Peripheral joints such as knees and shoulders are involved 20% of the time, with arthritis, enthesitis, and/or dactylitis
Both bone formation (syndesmophytes, enthesophytes, and ankylosis) and bone destruction (articular surface erosions) can be present
Radiographic changes develop about 5 years after symptoms
On MRI, sacroiliitis is bilateral 91% of the time.
Sacroiliitis is symmetric 86% of the time on radiography, and 60% of the time on MRI
MRI of the SI joints may be useful for early diagnosis if radiographs are negative
Active inflammatory changes, including subchondral marrow edema, synovitis, and enthesitis, are better seen on MRI
Mixed Connective Tissue Disease (MCTD)
Typically presents between 3rd and 5th decades
Approximately 9:1 female:male ratio
Diagnostic criteria include positive anti–U1 RNP antibody titer
A syndrome with clinical, pathological, and imaging features of RA, systemic sclerosis (SS), systemic lupus erythematosus (SLE), and/or polymyositis
RA: Juxta-articular osteoporosis, joint space narrowing, marginal erosions, synovitis
SS: Soft tissue swelling, soft tissue atrophy (late), calcifications, tuftal resorption, DIP joint erosions
SLE: Joint deformities without erosions, juxta-articular osteoporosis, tenosynovitis, AVN (in large joints such as hips)
Raynaud’s phenomenon is the most common initial symptom, followed by arthralgias
Most commonly involved joints are hands (PIPs, MCPs), wrists, feet (MTPs), and knees
MRI findings include synovial hypertrophy and tenosynovitis Extraarticular findings, such as cellulitis and myositis, may also be seen
Can occur at any stage of HIV illness
Rarely, can precede the diagnosis of HIV
Unclear etiology; direct viral infection of the joint has been suggested as a possible cause
Usually short-lived with a peak intensity of 1-6 weeks, though chronic destructive arthropathy may develop
Typically oligoarticular, and asymmetric
Affects peripheral joins, such as the knees and ankles
Radiography may show a joint effusion, which is sterile on aspirated
Chronic form can mimic RA, with osteoporosis, soft tissue swelling, bone erosion
Periosteal reaction and new bone formation may distinguish from RA
HIV infection can in some cases lead to remission of SLE, RA, and psoriasis, possibly due to profound immunosuppression
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