Crystal Associated Arthritis Flashcards
What is the aetiology of Gout?
Prevalence 1%
- male predominance 10:1
- most common inflammatory arthritis in men >40yrs
What is Gout?
Pathological reaction of joint/periarticular tissues to presence of monosodium urate monohydrate (MSUM) crystals
Where do MSUM crystals tend to deposit?
Peripheral connective tissues in/around synovial joints
- initially favour lower limb
- first presents at 1st MTP joint
At which joints does Gout present?
1st presents at 1st MTP joint
Progressive involvement of proximal sites
-development of 2o OA
What are the risk factors for Gout?
Hyperuricaemia Age Metabolic syndrome High protein diet High alcohol intake (beer)
What are the 2o causes of Gout?
Factors that impair excretion of uric acid -CKD -drugs (NSAIDs/thiazides) -HTN -hyperparathyroidism -hypothyroidism Factors that increase production of uric acid -metabolic conditions -myelo/lymphoproliferative conditions
What are the 1o causes of Gout?
Inherited isolated defect in uric acid excretion (90%)
Specific inherited enzyme defect of purine synthesis (1%)
-presents <25yrs
-uric acid stones in urinary tract
How does Acute Urate Gout present?
In first attack affects single, distal joint
Severe pain
-often wakes pt
-rapid onset
-max severity in 2-6hrs
-extreme tenderness/marked swelling w/ erythema
Fever/malaise/confusion
What are the precipitants of an Acute Urate Gout attack?
Excess food/alcohol
Dehydration
What is the natural hx of an Acute Urate Gout attack?
Self-limiting over 5-14 days w/ complete return to normality
- desquamation of overlying skin common
- some milder episodes lasting only a few days
- multiple joints affected in cluster attacks
What is the main differential for Acute Urate Gout, and what features separate them?
Septic arthritis
- more subacute in onset
- progresses in severity until treated
- range of movement limited
- systemic sx
What is Chronic Tophaceous Gout?
Large MSUM crystal deposits producing irregular firm nodules (tophi)
- extensor surfaces of fingers
- hands
- elbows
- achilles tendon
How does Chronic Tophaceous Gout present?
Tophi nodules
Chronic joint pain
Superimposed acute attacks
What feature distinguishes Tophi nodules from Rheumatoid nodules?
White colour
What complication of large Tophi nodules may occur?
Ulcerate
- discharges white, gritty material
- associated w/ local inflammation
- v. late feature
What investigations may be appropriate in Chronic Tophaceous Gout?
Bloods - FBC, U&Es, serum uric acid
Aspiration of joint effusions (MCS, polarised light microscopy)
XR
Search for underlying cause
What is the management of acute Gout attacks?
Fast-acting oral NSAIDs (colchicine in some pts)
Early aspiration of joint w/ corticosteroid injection
Early mobilisation
What is the long term management of Gout?
Hypouricaemic drugs (Allopurinol) -bring serum uric acid level into lower 1/2 of normal range Uricosuric drugs (Probenecid/Sulfinpyrazone)
What are the indications for the use of Hypouricaemic drugs?
Recurrent attacks of gout Tophaceous gout Evidence of bone/joint damage Associated renal disease Greatly elevated uric acid levels
How should Gout treatment be monitored?
Serum uric acid level measured every month
-dose inc in 100mg increments (max 900mg)
When is the long term management of Gout initiated?
After an acute attack has settled (4wks)
-give concurrent NSAIDs for this period to avoid triggering acute attacks
How does Allopurinol work?
Xanthine Oxidase Inhibitor
-reduces uric acid production
What lifestyle advice should be given to Gout pts?
Reduce alcohol
Reduce total calorie/cholesterol intake
Avoid certain food groups (offal, fish, spinach)
What are the contraindications to Uricosuric drugs?
Renal impairment
Pts w/ hx of Urolithiasis
Over-producers of uric acid
What is Pseudogout?
Calcium pyrophosphate crystal deposition in hyaline/fibrocartilage of joints
-leads to chondrocalcinosis (visible on XR)
What are the causes of Pseudogout?
Sporadic Familial Metabolic -hyperparathyroidism -hypophosphatasia -hypomagnesaemia -wilson's disease
In which groups is Pseudogout most common?
Ageing women
What are the most common sites of Pseudogout?
Knee>Wrist>Pelvis
How does Pseudogout present?
Often asymptomatic OR
Acute self-limited synovitis OR
Chronic arthritis showing strong overlap w/ OA
What are the signs on examination of Pseudogout?
Signs of OA w/ superimposed synovitis
What investigations may be appropriate in Pseudogout?
Polarised light microscopy of aspirate (shows +vely biorefringent, rhomboid shaped crystals)
XR (chondrocalcinosis)
Screening for metabolic/familial predisposition
What is the management of Pseudogout?
Acutely as per Gout
Joint aspiration
What is Calcific Periarthritis?
Basic Ca Phos deposition in various tissues
- periarticular (calcific tendonitis)
- hyaline cartilage (in association w/ OA)
- s.c. tissue/muscle (in CTD)
