REHUMATOID ARTHERITIS: Affects 0.03%-1.5% of population. Most of white patients with RA have MHC class II type HLA-DR4 or DR1 or both. The concardence of RF +ive RA is increased 6times among dizygotic twins. The risk of RA in MZ twins is increased 30times when sibling has the disease.
The joints most commonly involved in RA are the MCP, PIP, wrist and MTP joints. The distribution of involvement is symmetrical and polyarticular, predominantly small joints are involved.
Hallmark of joint inflammation: stiffness, heat, redness, soft tissue swelling, pain and dysfunction.
Musculoskeletal complications:
A. Cervical supine: Half of all patients with chronic RA have radiographic involvement of the atlantoaxial joint. Patients with cervical spine involvement may present with occipital pain, sgns of myleopathy, weakness and paresthesias of the hands and drop attacks.
Indications for surgical treatment: neurologic or vascular compromise or intractable pain. The probabililty of cervical involvement is predicted by the severity of peripheral arthritis.
B. Popletial cyst: Also called Bakers cyst. Rupture of popletical cyst may resemble acute trhombophelbitis(pseudophelibits). Fever, leukocytosis and ecchymosis around the ankle(cressent sign) can occur with rupture.
Ultrasonography can distinguish a cyst from popletial artery aneurysm, lymphoadenopathy, phlebitis and tumor.
Treatment of popletial cyst requires improvement in knee arthritis.
C. tenocynovitis: of the finger flexor and extensor tendon sheath is common and lead to tendon rupture. Other tenosynovitis syndrome in RA include de Quervian and wrist tenosynovits. Treatment of acute tenosynovitis include immobilization, warm soaks, NSAIDs and local corticosteroids injections in the sheath.
D. Carpel tunnel syndrome: RA is common cause of carpel tunnel syndrome- parestheisas of the hand in a typical median nerve distribution.
Treatment: resting splints, control of inflammation and local corticosteroids injections. Surgical release for persistent symptoms.
Extraarticular complications: occurs exclusively in seropositive RA.
Rehumatoid nodules: MC extraarticular complication. Occurs over extensor surfaces and at pressure points and are prone to ulceration and infection.
Rehumatoid vasculitis: occurs in the setting of severe, deforming arthritis and a high titre of RF. Rheumatoid vasculitis is mediated by the deposition of circulating immune complexes in the blood vessel walls.rehumatoid vasculitis comprises a spectrum of vascular disease including rheumatoid nodules and oblitirative endarteriopathy, leukocytoclastic small vessel vascultis(produces palpable purpura or cutenous ulceration, particularly over the malleoli of lower extremities). And secondary polyarteritis(clinically and histopathologicaly identical to PN, results in mononeuritis multiplex).

Neurological manifestations: mild peripheral sensory neuropathy, painful sensory-motor neuropathy suggests vasulitis or nerve entrappement. Cervical vertebral sublaxation can cause mylopathy. Erosive changes may promote the bassilr inviaginatin of the odontoid process of C2 into underside of the brain→spinal cord compression which may lead to death.
Pulmonary manifestations: Rehumatoid pulmonary disease is common but asymptomatic until pleural effusion interfere with respiration.
The exudative pleural fluid is remarkable for low level of glucose. High resolution CT helps to distinguish among rheumatoid associated interstitial lung disease, including interstitial pneumonitis, interstitial fibrosis and bronchiolitis oblitirans with or without organizing pneumonia.
MTX hypersensitivity pneumonitis may be life threatening complication of therapy.
Cardiac abnormalities: Patients rarely present with acute pericardial symptoms despite frequent serous pericarditis.
Rheumatoid pericardial disease frequently presents with edema or ascities due to occult constrictive disease. Chronic constrictive disease necessitates surgical treatment.
Liver abnormalities: increased level of liver enzymes, particularly alkaline phosphatase may occur in RA. Nodular hyperplasia of the liver can complicate RA and leads portal hypertension and hypersplenism.
Ophthalmic abnormalities: keratoconjuctivitis siccia or secondary Sjogran syndrome is the most common ophthalmic complication in RA. Sever scleritis progressive to scleromalacia perforans causes blindness.
Labs: Normocytic anemia, leukocytois, thrombocytosis and hypoalbuminemia.
RF not specific for RA. Anti CCP(citulinated protein) antibodies may present when RF is absent, are equal sensitive and more specific than RF.
Synovial fluid- cloudy, light yellow, poor viscosity and contains 10,000 to 75,000 leukocytes/Ál predominantly neutrophils.
The characteristic radiological changes: periarticular osteoporosis, systemic narrowing of joint space and bony erosion of joints of margins. These occur earliest in the hand and MTP joints.
Natural history of RA:
In a third of patient the onset of RA is rapid(days or weeks).
Among the patients with RA 70-90%have persistant chronic progressive arthritis.
The relationship between disease duration and inability to work is nearly linear.
Treatment: Goal of management include relieve inflammation and pain and maintaining function. A disease modifying regimen is started when RA is diagnosed. Low dose prednisone may be necessary to preserve function during initiation of DMARD therapy. With disease modifying agents uninterrupted treatment for 3-6 months is needed to assess efficacy.
Surgery in treatment: orthopedic surgery is most important advance in treatment of medical resistant RA.
Total arthoplasty has a slight poorer long term outcome in RA than OA.