Rheumatoid arthritis (musculoskeletal manifestations)
Updates to Article Attributes
Rheumatoid arthritis (RA) is a chronic multi-system disease with predominant musculoskeletal manifestations. Being a disease that primarily attacks synovial tissues, RA affects synovial joints, tendons and bursae.
Refer to the related articles for a general discussion of rheumatoid arthritis and for the particular discussion of its respiratory manifestations.
Radiographic features
Regarding the disease detection, as the early RA manifestations are non-osseous in nature, US and MRI have shown to be superior to radiographs and CT. Radiography, however, remains the mainstay of imaging in the diagnosis and follow-up of RA 2.
Radiograph
One large cohort study showed that radiographically demonstrable erosions were present in 30% of patients at diagnosis, and in 70% three years later 4.
The radiographic hallmarks of rheumatoid arthritis are:
- soft tissue swelling:
- fusiform and periarticular; it represents a combination of joint effusion, oedema and tenosynovitis 5
- this can be an early/only radiographic finding
- osteoporosis: initially juxta-articular, and later generalised; compounded by corticosteroid therapy and disuse
- joint space narrowing: symmetrical or concentric
- marginal erosions: due to erosion by pannus of the bony “bare areas”
Hands and wrists
Diagnosis and follow-up of patients with RA commonly involves imaging of the hands and wrists. The disease tends to affect the proximal joints in a bilaterally symmetrical distribution.
There is a predilection for:
- PIP and MCP joints (especially 2nd and 3rd MCP)
- ulnar styloid
- triquetrum
As a rule, the DIP joints are spared.
Late changes include:
- subchondral cyst formation: destruction of cartilage presses synovial fluid into the bone
- subluxation causing:
- ulnar deviation of the MCP joints
- boutonniere and swan neck deformities
- hitchhiker’s thumb deformity
- carpal instability: scapholunate dissociation, ulnar translocation
- ankylosis
Feet
- similar to the hands, there is a predilection for the PIP and MTP joints (especially 4th and 5th MTP)
- involvement of subtalar joint
- posterior calcaneal tubercle erosion
- hammertoe deformity
- hallux valgus
Shoulder
- erosion of the distal clavicle
- marginal erosions of the humeral head: the superolateral aspect is a typical location 2
- reduction in the acromiohumeral distance: "high-riding shoulder" due to subacromial-subdeltoid bursitis and high incidence of rotator cuff tear
Hip
- concentric loss of joint space, compared with osteoarthritis (OA) where there is a tendency for superior loss of joint space
- acetabular protrusio
Knee
- joint effusion
- typically involves the lateral or non-weight bearing portion of the joint
- loss of joint space involving all three compartments
- lack of subchondral sclerosis and osteophytes, compared with OA
- prepatellar bursitis
Spine
The cervical spine is frequently involved in RA ( in approximately 50% of patients), whereas a thoracic and lumbar involvement are rare. Findings include:
- erosion of the dens
-
atlantoaxial subluxation
- atlantoaxial distance in more than 3 mm on a flexion radiograph
- atlantoaxial impaction (cranial settling): cephalad migration of C2
- erosion and fusion of uncovertebral (apophyseal joints ) and facet joints
- osteoporosis and osteoporotic fractures
- erosion of spinous processes
Ultrasound
Sonography can assess the soft tissue manifestations of RA. In particular:
- synovial proliferation and inflammation of the superficial joints
- tenosynovitis: extensor carpi ulnaris tendon involvement is common in early disease and may lead to erosion of the ulnar styloid 2
- bursitis
Ultrasound also has a role in guiding corticosteroid injections in this setting.
CT
CT is not routinely used in the evaluation of peripheral RA. It has applications in imaging of the spine, and peri-operative assessment 2.
MRI
MRI is particularly sensitive to the early and subtle features of RA.
Commonly used sequences include T1-weighted contrast-enhanced spin-echo with fat saturation and T2-weighted spin-echo or gradient-echo sequences 2.
Features of RA best demonstrated with MRI include 2:
- synovial hyperaemia: indication of acute inflammation
- synovial hyperplasia (rice bodies)
- pannus formation
- decreased thickness of cartilage
- subchondral cysts and erosions:
- MRI is much more sensitive than radiography
- it is thought that subchondral cysts in RA eventually progress to erosions (i.e. constitute "pre-erosions")
- contrast enhancement may distinguish erosions or pre-erosions from degenerative subchondral cysts
- juxta-articular bone marrow oedema
- joint effusions
Differential diagnosis
The differential for the skeletal manifestations of RA includes:
- osteoarthritis
- involves the: DIPs, PIPs,
1st1st CMC joints - nonuniform joint space loss, subchondral sclerosis and osteophyte. soft tissue swelling: Heberdon’s node (DIPs) and Bouchard node (PIPs). no Erosions and no anklylosis.
- involves the: DIPs, PIPs,
-
erosive osteoarthritis:
- clinically an acute inflammatory attacks (swelling, erythema, pain) in postmenopausal woman
- typically includes the DIPs, PIPs 1st CMC joint 6, but not The metacarpophalangeal (MCP) joints and large joints.
- classic central erosions. possible ankylosis.
-
psoriatic arthritis (PsA):
- commonly involves the hands and there is an interphalangeal predominant distribution in PsA vs. MCP joint predominance in rheumatoid arthritis (RA)
- starts with erosions in the margins and eventually involves thewhole joint. classic: “pencil in cup” and bone proliferation (unlike RA). osteoporosis not a feature in PsA.
- MRI dynamic enhancement pattern may differentiate PsA from RA at 15 minutes
-
reactive arthritis (Reiter syndrome):
- predilection for the lower limb
- osteopenia and then osteoporosis, uniform joint space loss, subchondral cyst formation, subluxations, marginal erosions but no bone formation.
- symmetrical involvement of the: PIPs, MCPs, and carpal bones.
-
systemic lupus erythematosus (SLE)/Jaccoud arthropathy:
- joint space loss, subchondral sclerosis, osteophyte, and ulnar deviation of the phalanges without erosions
-
calcium pyrophosphate
dehydratedihydrate (CPPD) arthropathy- usually only
inaffects theMCPsMCP's: symmetric joint space narrowing, subchondral cysts, and osteophytes. unlike RA: chondrocalcinosis and no erosions
- usually only
-
gout
- usually in older men
- punched out erosions usually with a sclerotic border and overhanging edges, tophi, most commonly involves the 1st MTP known as podagra
Specific sitesSite specific differential diagnosis:
-<li>involves the: DIPs, PIPs, 1st CMC joints</li>- +<li>involves the: DIPs, PIPs, 1<sup>st </sup>CMC joints</li>
-<li>calcium pyrophosphate dehydrate (CPPD) arthropathy<ul><li>usually only in the MCPs: symmetric joint space narrowing, subchondral cysts, and osteophytes. unlike RA: chondrocalcinosis and no erosions </li></ul>- +<li>
- +<a title="CPPD" href="/articles/calcium-pyrophosphate-dihydrate-deposition-disease">calcium pyrophosphate dihydrate (CPPD) arthropathy</a><ul><li>usually only affects the MCP's: symmetric joint space narrowing, subchondral cysts, and osteophytes. unlike RA: chondrocalcinosis and no erosions </li></ul>
-<li>gout<ul>- +<li>
- +<a title="Gout" href="/articles/gout">gout</a><ul>
-</ul><p>Specific sites differential diagnosis: </p><ul>- +</ul><p>Site specific differential diagnosis: </p><ul>
Unable to process the form. Check for errors and try again.