Orthopaedics Notes

ORTHOPAEDICS

Contents:

• Gout

• Psoriatic arthritis

• Psuedogout

• Rheumatoid arthritis

To view pictures, just hit the link!

GOUT

Summary Points

• Gout is caused by the deposition of monosodium urate crystals in a joint

• Patients present with acute, severely painful, swollen joint

• Confirm with synovial fluid aspiration, as gout crystals are negatively birefringent under polarised light

• Manage acute attacks with NSAIDs, and allopurinol for prophylaxis from future attacks

Aetiology and Pathophysiology

Gout is a condition whereby there is deposition of monosodium urate monohydrate crystals in joints causing inflammation and eventual tissue damage. It is one of the most acutely painful conditions known. They affect the joints of the upper and lower limbs.

Types:

• Primary 95% - acute attacks, genetic influence due to overproduction or underexcretion of uric acid

• Secondary 5% - usually due to chronic diuretic therapy/changes in uric acid metabolism

Further subdivided into:

• Asymptomatic

• Hyperuricaemic

• Acute

• Intercritical/chronic tophaceous

Most patients with hyperuricaemia never develop gout and patients with gout do not need to have hyperuricaemia at the time of presentation. Crystals deposited in and around joint and can be found in synovial fluid

Most cases are due to the undersecretion of uric acid. <10% are due to its overproduction. However, important to note that you can have normoproduction w/ gout, so associated risk factors play a significant role.

Epidemiology and Associated Risk Factors

Incidence 12-18/100,000

Asian and Pacific Islanders have a much higher prevalence and a more severe disease.

Risk factors:

• Male sex (5:1) - female prevalence increases after menopause

• Meat and seafood

• Alcohol

• Obesity, high triglycerides, hypertension, coronary heart disease

• Diabetes mellitus

• Chronic kidney disease

• Asian ethnicity

• Drugs – chemotherapy, diuretics

• Trauma and joint morbidity

• Leukaemia

Presentation

Classically, gout presents as an acutely painful joint which is swollen, tender and erythematous, reaching a crescendo over 6-12hrs. Inflammation peaks within 24hrs, often with fever and malaise.

50% all attacks and 70% of first attacks affect the first metatarsophalangeal joint. Other sites: knee, midtarsal, wrist, ankle, small hand joints, elbows

Attacks are often spontaneous but may be triggered by trauma, surgery, alcohol consumption, starvation, infection or exercise.

Other atypical presentations:

• Tenosynovitis

• Bursitis

• Cellulitis

• Sore eyes - as the crystals can deposit in the conjunctiva

If chronic tophacecous gout, there may be irregular firm nodules (mainly around extensor surfaces of fingers, hands, forearms, elbows, Achilles tendon and ear) which are typically asymmetrical with a chalky appearance beneath the skin. Some only present with connective tissue tophi. Less often, patients present with painful tophaceous deposits and discharge in Heberden's (distal IP) and Bouchard's nodes (proximal IP).

Assessment

- O/E –

• Synovitis, swelling and extreme tenderness w/ overlying erythema

• Pyrexia

• Restricted movement, crepitus and deformity.

• Tophi (irregular firm nodules, where the monosodium urate crystals have deposited)

• Heberden’s or Bouchard’s nodes, that may discharge

Picture links:

• http://upload.wikimedia.org/wikipedia/commons/2/28/Gout2010.JPG

• http://upload.wikimedia.org/wikipedia/commons/0/0e/ChronicGout.jpg

- Ix –

Must differentiate from psuedogout by inspecting crystals under polarised light

Synovial fluid aspirate -Gout crystals arenegativelybirefringent. It may require repeating if no crystals found.

Picture link: http://upload.wikimedia.org/wikipedia/commons/a/ac/Fluorescent_uric_acid.JPG

Blood -

Serum uric acid levels - establishes risk but not useful diagnostic aid. >360 = raised. Uric acid levels may fall during an acute attack

Glucose to rule out DM

Lipids - associated w/ metabolic syndrome

Urine - 24hr urine sampling - renal uric acid secretion, useful for families

Imaging -

XR - soft tissue swelling in early stages, later can see punched out erosions in juxta-articular bone. Joint space preserved until late.

Rx

The objective is to alleviate pain and inflammation.

Conservative

• Resolves spontaneously in 5-15 days untreated with itching and desquamation of the overlying skin.

• Rest + Ice + Elevate

• Fluid therapy

• Advise - lose weight, exercise, diet, reduce alcohol intake and increase fluid intake

Medical

In an acute attack:

• NSAIDs first line - none specified but naproxen, diclofenac or indometacin are generally preferred. May be contraindicated for peptic ulcer disease, heart failure and if on anti-coagulants.

• Colchicine (an alkaloid with an unknown mechanism) is used when NSAIDs are contraindicated (or may be preferred by the individual) and is first line w/ NSAIDS according to European League Against Rheumatism. Start colchicine on 1mg increasing by 0.5mg every 2hrs until toxicity develops (nausea, diarrhoea and vomiting), the max dose being 6mg.

• Steroids if NSAIDs and colchicines are contraindicated (e.g. in renal impairment). There are many ways of administration these steroids - PO, IM, IV or intra-articular.

Prophylaxis: (If have >1 attack/yr think about prophylaxis)

• Allopurinol (xanthine oxidase inhibitor -> reduces uric acid synthesis) is first-line but never start it during an acute attack as it worsens the problem (wait 3 weeks).

  • Should start NSAIDs/colchicine/steroids with it for 1-3 months.

  • Start 50-100mg and increase (typically to 200mg) until serum uric acid <300. Max dose 900mg.

  • Do not stop allopurinol in a new acute attack

  • Allopurinol is not indicated for use in hyperuricaemic gout

  • Possible side effects include a rash, fever and leucopenia

Alternatives (that increase urinary excretion of uric acid):

• Sulfinpyrazone - if allopurinol toxicity occurs

• Probenecid

• Febuxostat - recommended by NICE if allopurinol intolerant, or if it is contra-indicated

Prognosis and Complications

Complications:

• Can lead to...

Buy the full version of these notes or essay plans and more in our Medicine and Surgery Pack Notes.