·         Cause ─ unknown

o       Possible genetic predisposition

o       Questionable reaction to antigen from Epstein-Barr virus

·         Age

o       Highest incidence 40-50 years

·         Female preponderance 3:1 under the age of 40

o       M:F = 1:1 if >40 years

·         Pathogenesis

o       Injury to synovial endothelial cells leads to

o       Synovitis with synovial hypertrophy which leads to

o       Impaired nutrition with necrosis of cartilage and resultant

o       Joint narrowing

§         Subluxation

§         Ankylosis

·         Clinical findings

o       Diagnostic criteria of American Rheumatism Association (at least 4 criteria should be present):

§         Morning stiffness for >1 hour

§         Swelling of >3 joints, particularly of wrist, metatarsophalangeal or proximal interphalangeal joints for >6 weeks

§         Symmetric swelling

§         Typical radiographic changes

§         Rheumatoid nodules

·         Biochemical tests

o       Positive rheumatoid factor

§         Rheumatoid factor

·         Positive in 85-94%)

·         IgM-antibody

o       Antinuclear antibodies

§         Positive in many

o       LE cells

§         Positive in some

o       Positive latex flocculation test

·         Location

o       Usually symmetric involvement of true, diarthrodial joints

·         Target areas

o       Proximal joints of hands and wrists

§         All five MCP, PIP joints and interphalangeal joint of thumb

§         All wrist compartments

·         Especially radiocarpal, inferior radioulnar, pisiform-triquetral joints

·         Early signs

o       Fusiform periarticular soft-tissue swelling (result of effusion)

o       Regional osteoporosis (disuse and local hyperthermia)

o       Widened joint space (rare to see)

o       Marginal and central bone erosions in small joints of hands and wrists

§         Less common in large joints

§         Site of first erosion is classically base of proximal phalanx of 4th finger

o       Erosion of the ulnar styloid and narrowing of the distal radioulnar joint

o       Atlantoaxial subluxation >2.5 mm (in >6%)

 

 

Lateral radiograph of the neck with the head in flexion shows an increased distance between
the anterior border of the dens and the posterior border of the anterior tubercle of C1 (blue line) from ligamentous laxity caused by rheumatoid arthritis. The "pre-dentate space," as this is called, should be less than 3 mm in the adult. The red line above should smoothly connect all of the spinolaminar white lines of each vertebral body but clearly is directed posterior to the spinolaminar white line of C1 (green arrow) since C1 is subluxed forward on C2.

Click here for this photo without annotations

 

 

 

o       Giant synovial cysts

·         Late signs

o       Diffuse loss of interosseous space

o       Flexion and extension contractures with ulnar subluxation and dislocation

o       Marked destruction of joint spaces

o       Extensive destruction of bone ends

o       Bony fusion

o       Elevation of humeral heads (from rotator cuff tears)

o       Resorption of distal clavicle

o       Erosion of superior margins of posterior portions of ribs 3-5

o       Destruction and narrowing of disk spaces

§         Irregular vertebral body outlines

§         Absence of osteophytosis

o       Destruction of zygapophyseal joints without osteophyte formation

o       Resorption of spinous processes

o       "Stepladder appearance" of cervical spine due to subluxations

o       Protrusio acetabuli (from osteoporosis)

o       Synovial herniation and cysts (eg, popliteal cyst)

o       Calcaneal plantar spur

·         Extra-articular manifestations (76%)

o       Felty’s syndrome (<1%)

§         Rheumatoid arthritis (present for >10 years)

§         Splenomegaly

§         Neutropenia

·         Age

o       40-70 years

·         F > M

o       Rare in African-Americans

o       Sjögren’s syndrome (15%)

§         Keratoconjunctivitis

§         Xerostomia

§         Rheumatoid arthritis

o       Pulmonary manifestations

§         Pleural effusion, mostly unilateral, without change for months

·         Usually not associated with parenchymal disease

§         Interstitial fibrosis with lower lobe predominance

§         Rheumatoid nodules (30%)

·         Well-circumscribed

·         Peripheral

·         Frequent cavitation

o       Caplan’s syndrome

§         Hyperimmune reactivity to silica inhalation with rapidly developing multiple pulmonary nodules

o       Pulmonary hypertension secondary to arteritis

·         Subcutaneous nodules

o       In 5-35% with active arthritis over extensor surfaces of forearm

o       Other pressure points (eg, olecranon) without calcifications (DDx to gout)

·         Cardiovascular involvement

o       Pericarditis (20-50%)

o       Myocarditis (arrhythmia, heart block)

o       Aortitis (5%) of ascending aorta ± aortic valve insufficiency

·         Rheumatoid vasculitis

·         Neurologic sequelae

o       Distal neuropathy (related to vasculitis)

o       Nerve entrapment (atlantoaxial subluxation, carpal tunnel syndrome, Baker cyst)

·         Lymphadenopathy (up to 25%)

o       Splenomegaly (1-5%)