Must know about Rheumatoid arthritis (RA)

►Rheumatoid arthritis (RA) is the most common form of chronic inflammatory arthritis and often results in joint damage and physical disability.

►Pleural disease, the most common pulmonary manifestation of RA, may produce pleuritic chest pain and dyspnea, as well as a pleural friction rub and effusion. 

►The earliest involved joints are typically the small joints of the hands and feet. The initial pattern of joint involvement may be monoarticular, oligoarticular (4 joints), or polyarticular (>5 joints), usually in a symmetric distribution. 

►Once the disease process of RA is established, the wrists, metacarpophalangeal (MCP), and proximal interphalangeal (PIP) joints stand out as the most frequently involved joints 

►Inflammation about the ulnar styloid and tenosynovitis of the extensor carpi ulnaris may cause subluxation of the distal ulna, resulting in a "piano-key movement" of the ulnar styloid. 

►Flatfoot deformity is by far the most common hindfoot deformity in rheumatoid arthritis

►One of the most common manifestations of RA in the
hands is tenosynovitis in flexor tendon sheaths; this can
be a major cause of hand weakness.

►The atlantoaxial joint is
prone to subluxation in several directions and is summarized
later.
• The atlas can move: anteriorly on the axis (most
common). > Posteriorly > Vertically
•The earliest and most common symptom of cervical subluxation
is pain radiating up into the occiput.

►RA can be associated with generalized osteopenia
and osteoporosis owing to the effects of drugs
The fibula is the most common fracture site.

►The most frequent site of cardiac involvement in RA is the pericardium. 
Mitral regurgitation is the most common valvular abnormality in RA.

►Rheumatoid vasculitis is seen most commonly in patients with long-standing disease, a positive test for serum RF, and hypocomplementemia; the overall incidence is quite rare, occurring in no more than 1% of cases.

►The most frequently recognized skin lesion in RA is the
rheumatoid nodule. They occur most often on extensor surfaces or pressure points, such as the olecranon process and the proximal ulna, as well as on tendons.
They are subcutaneous and vary in consistency from a soft,
amorphous, entirely mobile mass to a hard, rubbery mass
attached firmly to the periosteum.

►Ocular Keratoconjunctivitis sicca is the most common ophthalmic manifestation of rheumatoid arthritis, with a reported prevalence of 15–25%.

►The most common flexor tendon to rupture in rheumatoid arthritis is FPL rupture, caused by scaphotrapezial synovitis. 

►A normochromic, normocytic anemia often develops in patients with RA and is the most common hematologic abnormality. 

►Felty's syndrome is defined by the clinical triad of neutropenia, splenomegaly, and nodular RA and is seen in less than 1% of patients.

►The most common histopathologic type of lymphoma is a diffuse large B-cell lymphoma.

►The overall mortality rate in RA is two times greater than the general population, with ischemic heart disease being the most common cause of death followed by infection. 

►IgM, IgG, and IgA isotypes of RF occur in sera from patients with RA, although the IgM isotype is the one most frequently measured by commercial laboratories.

►Muscle: In biopsy specimens, atrophy of type II fibers is most
common.

►AZA is most commonly used as a substitute
for MTX when there are contraindications or intolerance
to MTX