Rheumatoid arthritis Flashcards
What is RA?
Rheumatoid arthritis is an autoimmune condition that causes chronic inflammation of the synovial lining of the joints, tendon sheaths and bursa. It is an inflammatory arthritis. Synovial inflammation is called synovitis. Rheumatoid arthritis tends to be symmetrical and affects multiple joints. Therefore it is a symmetrical polyarthritis. Inflammation of the tendons increases the risk of tendon rupture.
Prevalence of RA?
It is three times more common in women than men. It most often develops in middle age but can present at any age. Family history is relevant and increases the risk of rheumatoid arthritis.
Genetic associations of RA?
HLA DR4 (a gene often present in RF positive patients)
HLA DR1 (a gene occasionally present in RA patients)
Antibodies in RA?
Rheumatoid Factor (RF) is an autoantibody presenting in around 70% of RA patients. It is an autoantibody that targets the Fc portion of the IgG antibody. All antibodies have an Fc portion on them that is used to bind to cells of the immune system. Rheumatoid factor targets this Fc portion on immunoglobin G (IgG). This causes activation of the immune system against the patients own IgG causing systemic inflammation. Rheumatoid factor is most often IgM however they can be any class of immunoglobulin.
Cyclic citrullinated peptide antibodies (anti-CCP antibodies) are autoantibodies that are more sensitive and specific to rheumatoid arthritis than rheumatoid factor. Anti-CCP antibodies often pre-date the development of rheumatoid arthritis and give an indication that a patient will go on to develop rheumatoid arthritis at some point.
Presentation of RA?
It typically presents with a symmetrical distal polyarthropathy. The key symptoms are joint:
Pain
Swelling
Stiffness
Patients usually attend complaining of pain and stiffness in the small joints of the hands and feet, typically the wrist, ankle, MCP and PIP joints in the hands. They can also present with larger joints affected such as the knees, shoulders and elbows. The onset can be very rapid (i.e. overnight) or over months to years.
There are also associated systemic symptoms:
Fatigue
Weight loss
Flu like illness
Muscles aches and weakness
TOM TIP:
Pain from an inflammatory arthritis is worse after rest but improves with activity. Pain from a mechanical problem such as osteoarthritis is worse with activity and improves with rest.
Palindromic Rheumatism?
This involves self limiting short episodes of inflammatory arthritis with joint pain, stiffness and swelling typically affecting only a few joints. The episodes only last 1-2 days and then completely resolve. Having positive antibodies (RF and anti-CCP) may indicate that it will progress to full rheumatoid arthritis.
Common Joints Affected
Proximal Interphalangeal Joints (PIP) joints
Metacarpophalangeal (MCP) joints
Wrist and ankle
Metatarsophalangeal joints
Cervical spine
Large joints can also be affected such as the knee, hips and shoulders
TOM TIP: The distal interphalangeal joints are almost never affected by rheumatoid arthritis. If you come across enlarged painful distal interphalangeal joints this is most likely to be Heberden’s nodes due to osteoarthritis.
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what is Atlantoaxial Subluxation
Atlantoaxial subluxation occurs in the cervical spine. The axis (C2) and the odontoid peg shift within the atlas (C1). This is caused by local synovitis and damage to the ligaments and bursa around the odontoid peg of the axis and the atlas. Subluxation can cause spinal cord compression and is an emergency. This is particularly important if the patient is having a general anaesthetic and requiring intubation. MRI scans can visualise changes in these areas as part of pre-operative assessment.
RA signs in the Hands
Palpation of the synovium in around joints when the disease is active will give a “boggy” feeling related to the inflammation and swelling.
Key changes to look for and mention when examining someone with rheumatoid arthritis are:
Z shaped deformity to the thumb
Swan neck deformity (hyperextended PIP with flexed DIP)
Boutonnieres deformity (hyperextended DIP with flexed PIP)
Ulnar deviation of the fingers at the knuckle (MCP joints)
Boutonnieres deformity
Boutonnieres deformity is due to a tear in the central slip of the extensor components of the fingers. This means that when the patient tries to straighten their finger, the lateral tendons that go around the PIP (called the flexor digitorum superficialis tendons) pull on the distal phalynx without any other supporting structure, causing the DIPs to extend and the PIP to flex.
Extra-articular Manifestations
Pulmonary fibrosis with pulmonary nodules (Caplan’s syndrome)
Bronchiolitis obliterans (inflammation causing small airway destruction)
Felty’s syndrome (RA, neutropenia and splenomegaly)
Secondary Sjogren’s Syndrome (AKA sicca syndrome)
Anaemia of chronic disease
Cardiovascular disease
Episcleritis and scleritis
Rheumatoid nodules
Lymphadenopathy
Carpel tunnel syndrome
Amyloidosis
Investigations of RA?
The diagnosis of rheumatoid arthritis is clinical in patients with features of rheumatoid arthritis (i.e. symmetrical polyarthropathy affecting small joints). A few extra investigations are required at diagnosis:
Check rheumatoid factor
If RF negative, check anti-CCP antibodies
Inflammatory markers such as CRP and ESR
X-ray of hands and feet
Ultrasound scan of the joints can be used to evaluate and confirm synovitis. It is particularly useful where the findings of the clinical examination are unclear.
Xray changes of RA?
Joint destruction and deformity
Soft tissue swelling
Periarticular osteopenia
Boney erosions
