Crystal Associated Arthritis

Question 1

What is the aetiology of Gout?

Answer 1

Prevalence 1%

• male predominance 10:1
• most common inflammatory arthritis in men >40yrs

Question 2

What is Gout?

Answer 2

Pathological reaction of joint/periarticular tissues to presence of monosodium urate monohydrate (MSUM) crystals

Question 3

Where do MSUM crystals tend to deposit?

Answer 3

Peripheral connective tissues in/around synovial joints

• initially favour lower limb
• first presents at 1st MTP joint

Question 4

At which joints does Gout present?

Answer 4

1st presents at 1st MTP joint
Progressive involvement of proximal sites
-development of 2o OA

Question 5

What are the risk factors for Gout?

Answer 5

Hyperuricaemia
Age
Metabolic syndrome
High protein diet
High alcohol intake (beer)

Question 6

What are the 2o causes of Gout?

Answer 6

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

Question 7

What are the 1o causes of Gout?

Answer 7

Inherited isolated defect in uric acid excretion (90%)
Specific inherited enzyme defect of purine synthesis (1%)
-presents <25yrs
-uric acid stones in urinary tract

Question 8

How does Acute Urate Gout present?

Answer 8

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

Question 9

What are the precipitants of an Acute Urate Gout attack?

Answer 9

Excess food/alcohol

Dehydration

Question 10

What is the natural hx of an Acute Urate Gout attack?

Answer 10

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

Question 11

What is the main differential for Acute Urate Gout, and what features separate them?

Answer 11

Septic arthritis

• more subacute in onset
• progresses in severity until treated
• range of movement limited
• systemic sx

Question 12

What is Chronic Tophaceous Gout?

Answer 12

Large MSUM crystal deposits producing irregular firm nodules (tophi)

• extensor surfaces of fingers
• hands
• elbows
• achilles tendon

Question 13

How does Chronic Tophaceous Gout present?

Answer 13

Tophi nodules
Chronic joint pain
Superimposed acute attacks

Question 14

What feature distinguishes Tophi nodules from Rheumatoid nodules?

Answer 14

White colour

Question 15

What complication of large Tophi nodules may occur?

Answer 15

Ulcerate

• discharges white, gritty material
• associated w/ local inflammation
• v. late feature

Question 16

What investigations may be appropriate in Chronic Tophaceous Gout?

Answer 16

Bloods - FBC, U&Es, serum uric acid
Aspiration of joint effusions (MCS, polarised light microscopy)
XR
Search for underlying cause

Question 17

What is the management of acute Gout attacks?

Answer 17

Fast-acting oral NSAIDs (colchicine in some pts)
Early aspiration of joint w/ corticosteroid injection
Early mobilisation

Question 18

What is the long term management of Gout?

Answer 18

Hypouricaemic drugs (Allopurinol)
   -bring serum uric acid level into lower 1/2 of normal range
Uricosuric drugs (Probenecid/Sulfinpyrazone)

Question 19

What are the indications for the use of Hypouricaemic drugs?

Answer 19

Recurrent attacks of gout
Tophaceous gout
Evidence of bone/joint damage
Associated renal disease
Greatly elevated uric acid levels

Question 20

How should Gout treatment be monitored?

Answer 20

Serum uric acid level measured every month

-dose inc in 100mg increments (max 900mg)

Question 21

When is the long term management of Gout initiated?

Answer 21

After an acute attack has settled (4wks)

-give concurrent NSAIDs for this period to avoid triggering acute attacks

Question 22

How does Allopurinol work?

Answer 22

Xanthine Oxidase Inhibitor

-reduces uric acid production

Question 23

What lifestyle advice should be given to Gout pts?

Answer 23

Reduce alcohol
Reduce total calorie/cholesterol intake
Avoid certain food groups (offal, fish, spinach)

Question 24

What are the contraindications to Uricosuric drugs?

Answer 24

Renal impairment
Pts w/ hx of Urolithiasis
Over-producers of uric acid

Question 25

What is Pseudogout?

Answer 25

Calcium pyrophosphate crystal deposition in hyaline/fibrocartilage of joints
-leads to chondrocalcinosis (visible on XR)

Question 26

What are the causes of Pseudogout?

Answer 26

Sporadic
Familial
Metabolic
   -hyperparathyroidism
   -hypophosphatasia
   -hypomagnesaemia
   -wilson's disease

Question 27

In which groups is Pseudogout most common?

Answer 27

Ageing women

Question 28

What are the most common sites of Pseudogout?

Answer 28

Knee>Wrist>Pelvis

Question 29

How does Pseudogout present?

Answer 29

Often asymptomatic OR
Acute self-limited synovitis OR
Chronic arthritis showing strong overlap w/ OA

Question 30

What are the signs on examination of Pseudogout?

Answer 30

Signs of OA w/ superimposed synovitis

Question 31

What investigations may be appropriate in Pseudogout?

Answer 31

Polarised light microscopy of aspirate (shows +vely biorefringent, rhomboid shaped crystals)
XR (chondrocalcinosis)
Screening for metabolic/familial predisposition

Question 32

What is the management of Pseudogout?

Answer 32

Acutely as per Gout

Joint aspiration

Question 33

What is Calcific Periarthritis?

Answer 33

Basic Ca Phos deposition in various tissues

• periarticular (calcific tendonitis)
• hyaline cartilage (in association w/ OA)
• s.c. tissue/muscle (in CTD)