An acute hot swollen joint

Question 1

Differential

Answer 1

Septic arthritis
Crystal synovitis->gout or pseudogout
Inflammatory arthritis->RA and seronegative arthropathies
Transient synovitis
Haemarthrosis

Question 2

History

Answer 2

Pain->septic and gout tend to have ++pain

Age and sex->all can present in adult, septic/reactive/inflammatory in child. Gout +in men. RA + in women.

Which joint:

• Gout-> first MTP
• Pseudogout->knee and wrist
• Multiples->inflammatory

Is the patient ill

Previous history->90% gout will have recurrent

Associated-> systemic features. Eye in reiters (conjunctivtis), RA (keratoconjunctivitis), JIA (uveitis)

History of STDs/Diarrhea
Recent viral infection

PMHx:

• malignancy, chemotherapy
• IVDU
• Bleeding disorder

Drug history:

• Diuretics + low dose aspirin + gout
• steroids = +risk of infection

Social:
- Alcohol->gout

Question 3

Examination

Answer 3

General:

• Fever, systemically unwell
• Rash, gouty tophi, eye signs
• Evidence of inflammatory disease

Joint:

• Complete joint examination
• Examination of others to exclude monoarthritis

Question 4

Investigations

Answer 4

FBC->leukocytosis in infection, and inflammation
ESR/CRP can be elevated in all
Calcium->may be elevated in pseudogout
Serum urate
Clotting screen if suspect haemarthrosis

XR->may be normal, show chondrocalcinosis of pseudogout, bony arosions with gout or inflammatory arthitis

Joint aspirate->send for MCS

USS->useful to detect effusion

Question 5

Most commonly affected joints with infection

Answer 5

Knee
Hip
Shoulder

Question 6

Causes of chronic monoarticular/involvement of 2-3

Answer 6

Mycobacterium

Fungi

Question 7

When does bacterial infection of joint most commonly occur and why

Answer 7

RA

Chronic inflammation + steroids predisposes to S aureus.

Question 8

Most likely infection of joints in IVDU

Answer 8

Strep
Staph
Gram negative
Pseudomonas

Question 9

Specific diagnostic criteria for RA

Answer 9

Morning stiffness
>3 joints
Hand joints
Symmetric
Rheumatoid nodules
\+RF
Radiographic changes

First four +ve for 6 weeks, and any four to diagnose

Question 10

Common blood results for RA

Answer 10

RF +ve, elevated erythrocyte sedimentation rate, an elevated C-reactive, protein, anemia, thrombocytosis, and low albumin

Question 11

What is the target uric acid level for gout

Question 12

Most common causes of red hot joint

Answer 12

Infection
Crystals
Trauma