Week 4 - monoarticular joint pain Flashcards
Describe the presentation of acute joint pain and swelling. (LO1)
- Very common in A&E.
- Can be caused by a wide number of different pathologies.
- When it seems to be acute monoarthritis, it is important to differentiate between septic arthritis and other types of monoarthritis.
- Knowing the difference between the presentation of each pathology is key to a quick diagnosis.
What are some key factors to find out about in the investigation of acute joint pain and swelling? (LO1)
- Onset.
- Site.
- Timeframe.
- Precipitating factors (trauma or surgery).
- Other symptoms (systemic symptoms such as fever).
- Previous episodes and past medical history.
Describe the initial investigation (before tests) of acute joint pain and swelling. (LO1)
- Look, feel, move.
- Check for redness, swelling, skin changes.
- Compare to contralateral joint.
- Check for joint effusion (patella tap/sweep test).
- Check nearby joints for involvement.
Describe the investigation of acute joint pain and swelling. (LO1)
- Blood tests: FBC, CRP - to check for tissue injury or sepsis.
- ESR - to check for rheumatological causes.
- Joint aspiration is performed - syringe used to remove fluid from joint.
- Fluid is inspected visually and also sent for tests.
- Tests of joint fluid include: WBC, microscopy, culture and sensitivity and light microscopy.
Describe the joint aspiration results of a normal joint. (LO1)
- Appearance: Clear.
- White cells (x10⁶/L): Normal (<200).
- Neutrophils (%): Low (<25%).
Describe the joint aspiration results of a joint with non-inflammatory arthritis. (LO1)
- Appearance: Clear/straw-coloured.
- White cells (x10⁶/L): Moderate (<2000).
- Neutrophils (%): Low (<25%).
Describe the joint aspiration results of a joint with inflammatory arthritis. (LO1)
- Appearance: Clear/cloudy yellow.
- White cells (x10⁶/L): High (>2000).
- Neutrophils (%): Low (<25%).
Describe the joint aspiration results of a joint with septic arthritis. (LO1)
- Appearance: Turbid (thick with suspended matter).
- White cells (x10⁶/L): Very high (>50,000).
- Neutrophils (%): High (>75%).
List the differentials for acute joint pain and swelling. (LO1)
- Gout.
- Pseudogout.
- Rheumatoid arthritis (rare to present as monoarticular but possible).
- Septic arthritis.
- Musculoskeletal injury - haemarthrosis.
Describe the features of septic arthritis as a differential for acute joint pain and swelling. (LO1)
- Infection of joint.
- Can cause irreversible articular cartilage damage.
- May lead to sepsis and possibly mortality.
- Joint aspiration is the main way to diagnose.
- Managed with empirical antibiotics and surgical washout and irrigation of the affected joint.
Describe the features of gout as a differential for acute joint pain and swelling. (LO1)
- Caused by monosodium urate crystals in joint.
- Form due to hyperuricaemia.
- Typically episodic.
- Identified via joint aspiration microscopy.
- Treated with NSAIDs.
Describe the features of pseudogout as a differential for acute joint pain and swelling. (LO1)
- Caused by deposits of calcium pyrophosphate crystals.
- Typically affects proximal joints.
Describe the features of rheumatoid arthritis as a differential for acute joint pain and swelling. (LO1)
- Autoimmune disease.
- Small joints in hands and feet.
- Swollen, painful and red with stiffness.
- Systemic symptoms: fatigue, weight loss and fever.
- ESR will show raised inflammatory markers.
- NSAIDs for pain.
- DMARDs for management.
Describe the features of traumatic injury as a differential for acute joint pain and swelling. (LO1)
- Haemarthrosis - bleeding in the joint cavity.
- Bloods and plain film radiographs.
- Management: RICE.
What is crystal arthritis? (LO2)
- A type of arthritis causing severe pain due to crystals being deposited in the joints.
- 2 main types: gout, pseudogout.
Describe the pathophysiology of gout. (LO2)
Gout is the consequence of hyperuricaemia and high levels of uric acid crystal formation.
Prolonged hyperuricaemia leads to the formation of urate crystals which deposit in the synovium of the joint.
Inflammation is then caused in the joint due to phagocytosis of the crystals by polymorphonuclear leukocytes.
List the at-risk groups for gout. (LO2)
- Men >40 years.
- Women after menopause - oestrogen levels drop as oestrogen would help remove uric acid.
- Obese people.
- Diuretic users.
- Cancer patients.
- Those with hypertension and renal disease.
What are two ways in which gout could occur? (LO2)
Overproduction of uric acid or the underexcretion of uric acid.
List some causes of the overproduction of uric acid. (LO2)
- Excess purines in the diet.
- Alcohol abuse.
- Myeloproliferative disorder - abnormal production of WBCs.
- Lymphoproliferative disorder - excess production of lymphocytes.
List some causes of the underexcretion of uric acid. (LO2)
- Renal disease.
- Polycystic kidney disease (when cysts grow on the kidneys and cause damage).
Drugs are also capable of causing hyperuricaemia. List some of them. (LO2)
- Alcohol.
- Thiazides.
- Lasix.
- Aspirin.
List the two types of gout. (LO2)
- Chronic gout.
- Acute gout.
List the clinical features of acute gout. (LO2)
- Extremely painful.
- Joint swelling.
- Shiny, red skin.
- Warm joint.
- Multiple joints in severe cases.
- First metatarsophalangeal joint most commonly affected.
- Can affect ankles, knees, elbows, wrists and hands too.
- Attacks usually resolve themselves.
- If untreated, attacks become more frequent and bony erosive damage occurs.
List the clinical features of chronic gout. (LO2)
- Appears in patients with long-standing hyperuricaemia who have had many flares.
- Bony erosions form - deformity.
- Can lead to deterioration of kidney function and uric acid stones forming in the urinary tract.
List the 3 main investigations for gout. (LO2)
- Synovial fluid analysis.
- Blood tests.
- Radiology.
Describe the findings of a synovial fluid analysis as an investigation of gout. (LO2)
- Synovial fluid aspirated from symptomatic joint.
- Examined with microscope under polarised light.
- Crystals are needle-shaped.
- Strong negative birefringence - appear yellow if parallel to plane of light and blue if perpendicular.
- Gram tests should be done to rule out infection.
Describe the findings in a blood test as an investigation of gout. (LO2)
- WBC elevated.
- CRP elevated.
- ESR elevated.
- Serum uric acid elevated - 1/3 of patients have normal uric acid in acute flare-ups.
Describe the radiological findings in gout. (LO2)
Erosion of the bone with overhanging edges.
Describe the management of acute gout. (LO2)
- NSAIDs.
- Colchicine if patient is unable to have NSAIDs.
- Corticosteroids if patient is unable to have NSAIDs or colchicine.
Describe the management of chronic gout. (LO2)
- Uricosuric agents - most commonly allopurinol - inhibits enzyme Xanthine oxidase.
- Diet control.
- Alcohol consumption reduced.
- Colchicine prophylaxis.
What is pseudogout? (LO2)
A disease caused by the deposition of calcium pyrophosphate dihydrate (CPPD) crystals in a joint.
List the at-risk groups for pseudogout. (LO2)
- The elderly.
- Those with hypothyroidism.
- Those with hyperparathyroidism.
- Those with haemochromatosis.
What is the cause of pseudogout? (LO2)
The exact cause is unknown, however, it is associated with osteoarthritis and attacks are often preceded by other illnesses.
List the clinical features of pseudogout. (LO2)
- Pain.
- Swelling.
- Stiffness.
- Wrist and knees commonly affected.
- Appearance of affected joint is similar to gout.
Describe findings of a synovial fluid analysis as an investigation of pseudogout. (LO2)
- Calcium pyrophosphate dihydrate (CPPD) crystals appear as small and rod-shaped.
- Weak positive birefringence.
- Gram test should be done to rule out infection.
Describe the radiological findings in pseudogout. (LO2)
- Calcification can be seen on the meniscus of the knee or triangular cartilage of the wrist.