Rheumatoid arthritis (musculoskeletal manifestations)

Last revised by Mostafa Elfeky on 27 Dec 2023

Rheumatoid arthritis (RA) is a chronic multisystem disease with predominant musculoskeletal manifestations. It is a disease that primarily affects synovial tissues, i.e. 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 and/or cardiac manifestations.

Radiographic features

Regarding disease detection, as the early rheumatoid arthritis manifestations are non-osseous in nature, ultrasound and MRI have been shown to be superior to radiographs and CT. Plain radiography, however, remains the mainstay of imaging in the diagnosis and follow-up of rheumatoid arthritis 2

Plain 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:

  • marginal erosions; important early finding, in the “bare areas”, frequently in the radial side of the metacarpophalangeal (MCP) joints 7

  • soft tissue swelling

    • fusiform and periarticular; it represents a combination of joint effusion, edema and tenosynovitis 5

    • this can be an early/only radiographic finding

  • osteoporosis: initially juxta-articular, and later generalized; compounded by corticosteroid therapy and disuse

  • joint space narrowing: symmetrical or concentric, uniform

Hands and wrists

Diagnosis and follow-up of patients with rheumatoid arthritis commonly involve imaging of the hands and wrists. The disease tends to affect the proximal joints in a bilaterally symmetrical distribution. Although performing both hands on one radiograph is convenient, recent research has shown that the distortion due to divergent ray when imaging bilaterally can impact diagnosis and x-raying the hands individually is preferred at a minimal dose increase 8.

Rheumatoid arthritis is a synovial-based process, with a predilection for the:

  • proximal interphalangeal and metacarpophalangeal joints (especially those of the index and middle fingers)

  • ulnar styloid

  • triquetrum

As a rule, the distal interphalangeal joints are spared.

Late changes include:

  • joint effusion (elevated fat pads) 

  • joint space narrowing

  • periarticular erosions 

  • cystic changes

  • similar to the hands, there is a predilection for the proximal interphalangeal and metatarsophalangeal joints (especially of the fourth and fifth toes)

  • subtalar joint involvement

  • posterior calcaneal tubercle erosion

  • hammer toe deformity

  • hallux valgus

  • concentric loss of joint space, compared with osteoarthritis (OA) where there is a tendency for superior loss of joint space

  • acetabular protrusion

  • 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 osteoarthritis

  • prepatellar bursitis


The cervical spine is frequently involved in rheumatoid arthritis (in approximately 50% of patients), whereas thoracic and lumbar involvement is rare. Findings include:


Sonography can assess the soft tissue manifestations of rheumatoid arthritis. In particular:

  • synovial proliferation and inflammation of the superficial joints, which is often evident before bone changes are visible on radiographs

  • tenosynovitisextensor 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 is not routinely used in the evaluation of peripheral rheumatoid arthritis. It has applications in imaging of the spine, and peri-operative assessment 2.


MRI is particularly sensitive to the early and subtle features of rheumatoid arthritis.

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 rheumatoid arthritis best demonstrated with MRI include 2:

  • synovial hyperemia: an 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 rheumatoid arthritis 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 edema

  • joint effusions

Differential diagnosis

The differential for the skeletal manifestations of rheumatoid arthritis includes:

  • degenerative osteoarthritis

    • involves the proximal and distal interphalangeal joints, and the thumb carpometacarpal joint

    • non-uniform joint space loss, subchondral sclerosis, and osteophytes

    • soft tissue swelling: Heberden nodes at distal interphalangeal joints, and Bouchard nodes at proximal interphalangeal joints

    • no erosions and no ankylosis

  • erosive osteoarthritis

    • clinically acute inflammatory attacks (swelling, erythema, pain) in postmenopausal women

    • typically involves the proximal and distal interphalangeal joints and the thumb carpometacarpal joint 6, but not metacarpophalangeal joints or large joints

    • classic central erosions, possible ankylosis

  • psoriatic arthritis (PsA)

    • commonly involves the hands and there is an interphalangeal predominant distribution in psoriatic arthritis compared to metacarpophalangeal joint predominance in rheumatoid arthritis

    • starts with erosions in the margins and eventually involves the
      whole joint, the classic changes being the pencil-in-cup deformity and bone proliferation (unlike rheumatoid arthritis)

    • osteoporosis not a feature in psoriatic arthritis

    • MRI dynamic enhancement pattern may differentiate psoriatic arthritis from rheumatoid arthritis at 15 minutes

  • reactive arthritis

    • a 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 metacarpophalangeal and proximal interphalangeal joints 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 dihydrate (CPPD) arthropathy

    • usually only affects the metacarpophalangeal joints: symmetric joint space narrowing, subchondral cysts, and osteophytes

    • unlike rheumatoid arthritis: chondrocalcinosis and no erosions 

  • gout

    • usually in older men

    • punched out erosions usually with a sclerotic border and overhanging edges, tophi most commonly involves the metatarsophalangeal joint of the hallux (which is known as podagra)

Site-specific differential diagnosis: 

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