Inflammatory diseases of musculoskeletal system (rheumatoid polyarthritis, Bechterew’s disease)
Rheumatoid arteritis
RA is an autoimmune disease that causes chronic inflammation and destruction of the synovial joints. It affects about 3% of women and 1% of all men. It is a systemic disease and affects many different structures all over the body, unlike osteoarthritis which is a product of mechanical wear. Predominantly in RA small joints are affected, mostly in the hands and feet.
The precise etiology is unknown but genetics and the presence of major histocompatibility complex class II allele human leukocyte antigen (HLA, DRw4 is more common in patients with RA. Additionally, some bouts of RA are triggered in susceptible individuals by infections.
The pathophysiology of RA is centered around the synovium. The synovium shows increased angiogenesis, cellular hyperplasia, an influx of inflammatory cells, changes in the expression of cell surface adhesion molecules and many cytokines. The lining becomes hyperplastic with inflammatory cells invading the tissue, all triggering an inflammatory process within the synovial capsule. The very inflammatory setting, when not treated, leads to the eventual destruction of the involved joint.
Presentation of the patient is commonly with chronic hand/wrist/foot pain with selling in the fingers and stiffness worse in the mornings after getting up. Most patients are in their 50s,
symptoms are generally bilateral and chronic. In advanced forms a swan neck deformity is seen in the digits with distal interphalangeal hyperflexion and proximal interphalangeal hyperextension. Another variation of this is Boutonniere’s deformity where there is PIP flexion and DIP extension.
Once a clinical diagnosis Rheumatoid Factor (RF) should be looked for, it is positive in around 70% of cases. Anti-cyclic citrullinated peptide antibody (anti-CCP) is also present in about 70% of patients.
Treatment programs:
- Acute
- Mild at initial presentation
- Methotrexate 7.5mg orally once weekly
- With adjunct prednisolone 1-10mg once daily
- With NSAIDs
- Moderate-to-severe at presentation
- Methotrexate 7.5mg orally once weekly, increase up to 20mg/week
- Biologic - etanercept 50mg subcutaneously once weekly
- With adjunct prednisolone 1-10mg once daily
- With NSAIDs
- Ongoing (failure to manage disease after 3 months)
- Methotrexate 7.5mg orally once weekly, increase up to 20mg/week
- Biologic - etanercept 50mg subcutaneously once weekly
- With adjunct prednisolone 1-10mg once daily
- With NSAIDs
- SECOND LINE - triple therapy with synthetic DMARDs e.g. methotrexate + hydroxychloroquine + sulfasalazine
Complications include increased joint replacement surgery, increased CAD, Felty syndrome (RA + splenomegaly + low WBC)