Case 23- Arthritis Flashcards
Conditions classified as Spondyloarthropathies (autoimmune)
- Ankylosing spondylitis
- Psoriatic arthritis
- Enteropathy arthritis
- Juvenile Spondyloarthropathies
- Reactive arthritis
- Undifferentiated Spondyloarthropathy
HLA- B27
- Present in 50-95% of patients with SpA (white AS =95%)
- Prevalence ~10% in general population.
- 5-10% of those with HLA-B27 go on to develop SpA
Extra-articular features of Spondylarthropathies (SpA)
- Anterior uveitis
- Apical lung fibrosis
- Aortic insufficiency/ AV block/ IHD
- IgA nephropathy, Amyloidoses
- Autoimmune bowel disease
- (Achilles tendon) Enthesitis
Psoriatic arthritis (autoimmune)
- Joint pain character- inflammatory
- An inflammatory arthritis, associated with psoriasis of the skin or nails
- Affects 5-25% of patients with psoriasis
- Risk factors- Psoriasis, Western Caucasian, Middle age (35-55)
- Genetics (HLA-B27)
Psoriatic arthritis- joint involvement pattern
- Usually an asymmetrical oligoarthritis, but can present as a symmetrical polyarthritis
- Commonly affects wrists, hands (DIP joints rather than MCP unlike Rheumatoid), feet, ankles
- Can also involve tendons/ligaments (enthesitis)
- May also involve the Axial skeleton (spine)
- May see swelling of Entire digit (Dactylitis)
Psoriatic arthritis clinical examination/investigations
Psoriatic arthritis clinical examination= Pitting, Yellowing, Onycholysis (separation of nail from nail bed)
Psoriatic arthritis investigations- Usually Seronegative, unlike Rheumatoid factor, negative anti-CCP.
Septic arthritis (infective)
- Infection driving joint inflammation/destruction. Most commonly staph Aureus
- Risk factors- joint surgery/injection, Prosthesis, Immunosuppression, IVDU
- Joint pain character and pattern= regard a hot, swollen, acutely painful joint with restriction of movement as septic arthritis until proven otherwise. Delay will cause increased destruction
- Urgent recognition and treatment required as it can be limb and life threatening. Mortality rate is 10-20%
- Most commonly the knee joint is effected
- Diagnosis is confirmed by a positive culture from joint aspiration, it requires several weeks of IV and oral antibiotics
Gout (Crustal Arthropathy) Mechanism
- Uric acid is byproduct of purine degradation – humans can’t oxidise it – puts us at risk of monosodium urate deposition in states of hyperuraemia.
- Hyperuraemia is usually due to under excretion (alcohol, renal disease, drugs) rather than overproduction
- Gout is painful inflammatory response to monosodium urate crystals in joints
Rheumatoid arthritis pathology
- Post translational change of the amino acid Arginine into Citrulline
- Arginine is found in Type II collagen
- Susceptible genes= HLA-DR1, HLA-DR4
- Immune cells attack these Citrulline proteins and antibodies are produced against them
- Infiltration of the Synovial fluid with immune cells. Autoantibodies are produced
Gout (Crystal Arthropathy)
- Gout can be diagnosed via aspiration of the joint to look for crystals
- Monosodium urate crystals are, ‘strongly negative birefringent needle shaped crystals under polarised light microscopy
- If its clinically gout in MTP you do not need to routinely aspirate
- Clinical presentation is severe pain, swelling, warmth in <24 hours usually 1st MTP (big toe joint). In 75% the theory of cooler periphery leads to crystal deposition
Ankylosing spondylitis
- Chronic inflammatory arthritis affecting the Axial Skeleton – leads to inflammatory back pain from sacroiliitis (inflammation of the sacroiliac joints), pain and stiffness worse with rest, improves with movement, may awake from sleep.
- Associated to extra-articular features as described earlier in Spondyloarthropathy – enthesitis, uveitis, may also have some peripheral joint involvement
- Inflammation of the ligaments in the spine eventually leads to calcification forming syndesmophytes and eventual fusion of the spine – giving xray findings like bamboo spine and in chronic disease, the classic question mark posture – loss of lumbar lordosis, exaggerated throacic kyphosis
Ankylosing Spondylitis risk factors
- Male 2:1
- HLA-B27
- Young age of incidence (20-30)
Reactive arthritis
- Asymmetrical inflammatory oligoarthritis (sometimes with axial involvement), tending to affect the large joints of lower limb – reactive as it’s usually preceded by a gastrointestinal or genitourinary infection by 2-4 weeks prior. (Chlamydia, Salmonella, Campylobacter, Shigella, and Yersinia common preceeding organisms)
- Belonging to the spondyloarthropathy family it has a strong HLA B27 relation, with associated symptoms of enthesitis and uveitis being common.
- The classical triad is of arthritis, non-gonococcal urethritis, and conjunctivitis is frequently described but found only in a minority of cases and not required for diagnosis (“Can’t see, can’t pee, can’t climb a tree)
- 30-50% go on to develop a chronic arthritis
Reactive arthritis- multisystem effects
- Oligoarthritis
- Eye= Uveitis, sterile conjunctivitis
- Bladder- Sterile balantitis urethritis
- Skin= Keratoderma blennorrhagicum (12% of patient)
Pseudogout (CPPD)
- Calcium pyrophosphate crystals are shed into the intra-articular space and induce the inflammatory reaction, it can be diagnosed via aspiration and identification of the crystals
- Commonly present as monoarthritis
- Chondrocalcinosis (calcification of cartilage)- a potential sign of calcium pyrophate crystals
- Secondary causes should be investigated for in the <50’s, including hyperparathyroidism, hypomasnesmia, hemochromatosis and Wilson disease etc
Differentiating between CCPD and Gout
- CPPD- Positively birefringent rhomboid-shaped crystals under polarised light microscopy
- Gout- Strongly negative birefringent needle shaped crystals under polarised light microscopy
The Extra-articular features of Rheumatoid arthritis
- Fatigue, weight loss, fever
- Heart- Increased CVS risk, Pericarditis, Pericardial effusion
- Lungs- Pleural effusion, Interstitiail lung disease
- Eye- Sicca (dry eyes/mouth), Episcleritis/scleritis (inflammation of the sclera)
- Osteoporosis
- Carpal tunnel
Disease modifying anti rheumatic drugs (DMARDS)
These slow and even reverse the joint damage caused by an inflammatory arthritis generally by immunomodulation
Adjuncts of DMARDS
Non steroid anti-inflammatory drugs (NSAIDS) and steroids are used as adjuncts as there is a delay in the effect of DMARDS
Measuring severity of Rheumatoid arthritis
To measure level of disease activity in Rheumatoid arthritis we use DAS28. This is a combination of tender and swollen joint counts and a global assessment of health using ESR/CRP (0-100)
DAS-28
- 0 to <2.6- Remission
- 2.6 to 3.2- Low disease activity (LDA)
- > 3.2 to 5.1- moderate disease activity
- > 5.1= high disease activity
Medical management principles in rheuamtoid arthritis
- If patients are not reaching desired target (low disease activity) therapy is escalated
- NSAID + PPI +/- Steroids= adjuncts to DMARDS, given at the start of treatment before DMARD’s have their effect
- After the initial DMARD therapy you should re-assess at 3 months
- There should be a combination or change in DMARDs if not reaching the target
Two categories of DMARD’s
- Synthetic or conventional DMARD’s- these are older more established generally oral medication such as Methotrexate, Sulfasalazine, Leflunomide, Hydroxychloroquine etc
- Biological DMARD’s or targeted therapies- these are more modern medications targeted to particular inflammatory/immune pathways. They can be infusions, self-injected subcutaneously. Some newer ones are oral medication. Generally reserved for when treatment targets are not met by synthetic DMARD’s alone
Treatment for moderate and severe rheumatoid arthritis at presentation
Methotrexate monotherapy is preferred for initial management
AICAR
An analog of adenosine monophosphate (AMP) that is capable of stimulating AMP-dependent protein kinase (AMPK) activity – leads to increased adenosine release – anti-inflammatory properties