Crystal Arthropathies Flashcards
What is gout?
An inflammatory arthritis associated with hyperuricaemia and intra-articular sodium urate crystals.
Which joint does gout most commonly affect?
MTP joint of big toe.
Other common joints of gout.
Ankle
Foot
Small joints of the hand
Wrist
Elbow
Knees
It can also be polyarticular.
Who are more commonly affected of gout, women or men?
Men 4:1 Women
Risk factors of gout.
Hyperuricaemia
Male
Older age
Obesity
Diet with red meat high in purine
Alcohol (purine heavy + diuretic)
Medication like thiazides
Renal insufficiency
Post-menopausal females
Hypertension
Diabetes
Causes of hyperuricaemia.
Impaired excretion of uric acid such as;
Chronic renal disease
Drugs therapy like thiazides
HTN
Lead toxicity
Primary hyperpara or hypothyroidism
Increased lactic acid production from alcohol, exercise or starvation
Increased production of uric acid
Increased turnover of purines such as;
Polycythaemia vera
Leukaemia
Carcinoma
Clinical presentation of gout.
Acute onset of severe pain in an acute attack of gout.
Joint stiffness
Erythema and warmth.
The pain should be at its peak withing 24h and resolve within 2 weeks.
There can be swelling and tenderness of affected joint as well.
Gouty tophi can be present as well.
Where might you see tophi?
Elbows
Knees
Achilles tendons
Dorsal aspects of hands and feet as well as pinna/helix of the ear.
Differential diagnoses of gout.
Pseudogout
Septic arthritis
Cellulitis
RA
OA
Psoriatic arthritis
Sarcoidosis
Investigations of gout.
1st line - Synovial fluid analysis to look for monosodium urate crystals.
Other investigations might be considered such as;
Serum uric acid levels (may be normal)
Ultrasound
X-ray of affected joint
Dual energy computed tomography.
X-ray findings of gout.
Soft-tissue swelling in early stages
Well-defined punched out erosions seen in juxta-articular bone in late stages.
Lytic lesions in bone
The erosions can also have sclerotic borders with overhanging edges
What will aspiration of synovial fluid show in gout?
Monosodium urate crystals
-ve bacterial growth
Negatively birefringent of polarised light
Needle shaped crystal
Diagnostic criteria of gout.
1. Characteristic monosodium urate crystals in joint fluid, or
2. Characteristic monosodium urate crystals from tophus, or
- Fulfilment of ≥6 of the following criteria:
> one attack of acute arthritis
Maximum inflammation developed within 1 day
Monoarthritis attack, redness observed over joints
First metatarsophalangeal joint painful or swollen
Unilateral first metatarsophalangeal joint attack
Unilateral tarsal joint attack
Tophus (confirmed or suspected)
Hyperuricaemia
Asymmetrical swelling within a joint on x-ray film
Subcortical cyst without erosions on x-ray film
Joint culture negative for organism during attack.
Is joint pain and hyperuricaemia enough to diagnose gout?
No.
Also in an acute episode serum urate levels may go down.
Non-pharma management of gout.
Reduce consumption of purine-rich foods.
Weight loss
Adequate hydration.
What may precipitate an acute gout attack?
Excess food
Alcohol
Dehydration
Diuretic therapy
Treatment of acute gout.
High dose NSAIDs + PPi
If this is contraindicated colchicine can be given 500 mcg BD.
If there is renal failure then NSAIDs and colchicine are both CId.
Steroids oral/IM/intra-articular can be given.
Rest and elevate joint, ice packs and bed cages can also be used.
When to use prophylaxis of gout?
If 2 or more attacks in 12 months, tophi or renal stones.
CKD stage 2 or more
Prevention medication of gout.
Allopurinol titrated from 100mg/24h increasing every 4 weeks until plasma urate < 0.3 mmol/L.
Allopurinol should not be started until acute attack is over.
Febuxostats can also be used if allopurinol is CId or not tolerated.
Uricosuric agents can also be given.
What is pseudogout?
Calcium pyrophosphate dihydrate deposition arthropathy
There is deposition of calcium pyrophosphate dihydrate crystals in hyaline and fibrocartilage.
It is an acute monoarthropathy usually in larger joints in elderly.
It is usually spontaneous but can be provoked by illness, surgery or trauma.
It can be either acute or chronic.
Acute = monoarthropathy
Chronic = polyarthropathy that is symmetrical and very RA-like
Risk factors of pseudogout.
Old age
Hyperparathyroidism
Haemochromatosis
Hypophosphataemia
Investigations of pseudogout.
No bacterial growth
Calcium pyrophosphate crystals
Rhomboid shaped crystals
Positive birefringent of polarised light
X-ray
Serum calcium, urate, PTH, iron studies, magnesium, ALP
Diagnostic criteria of pseudogout.
Demonstration of CPP crystals in tissues or synovial fluid by definitive means, such as x-ray diffraction or chemical analysis.
Management of pseudogout.
Acute - Cool packs, rest, aspiration and intra-articular steroids.
NSAIDs + PPi +/- colchicine can prevent acute attacks.
Methotrexate and hydroxychloroquine may be consideed for chronic pseudogout.
Metabolic causes of pseudogout.
Haemochromatosis
Hyperparathyroidism
Hypomagnesaemia
X-ray changes in pseudogout.
Chondrocalcinosis is the classic xray change in pseudogout. It appears as a thin white line in the middle of the joint space caused by the calcium deposition. This is pathopneumonic (diagnostic) of pseudogout.
