Septic Arthritis

Question 1

What is the pathophysiology of Septic arthritis?

Answer 1

• Acute synovitis with purulent joint effusion
• Articular cartilage attacked by bacterial toxin and cellular enzyme
• Complete destruction of the articular cartilage
• Sequelae (1 of the following):
  
  • Complete recovery
  • Partial loss of the articular cartilage and subsequent OA
  • Fibrous or bony ankylosis

Question 2

What are the clinical features of acute septic arthritis in a neonate?

Answer 2

• Picture of septicaemia
• Irritability
• Resistant to movement
• Ill Child

Question 3

What are the clinical features of Acute Septic arthritis in a child?

Answer 3

• Acute pain - in single large joint
• Reluctant to move the joint
• Increase temperature and pulse
• Tenderness

Question 4

What are the clincal features of Acute Septic Arthritis in adults?

Answer 4

Triad

• Fever
• Joint Pain
• Decreased ROM

Plus

• Swelling
• Hot, swollen eythematous joint
• Fever and Malaise

Question 5

What investigations would you do if you suspected Acute Septic Arthritis?

Answer 5

• Bloods - FBC, ESR, CRP, Blood cultures
• Imaging - X ray, Ultrasound
• Other - USS guided Joint Aspiration

Question 6

How would you treat someone with acute septic arthritis?

Answer 6

• General supportive measures
  
  • Analgesia
• Antibiotics
  
  • Flucloxacillin +/- Rifampicin
  • IV Vancomycin (if MRSA)
• Emergency Surgical drainage & lavage where possible
• Physio as follow up

Question 7

What are the common orgasnisms which cause septic arthritis?

Answer 7

• Staphylococus aureus
• Haemophilus influenzae
• Streptococcus pyogenes
• E. coli

Question 8

What is are causes of septic arthritis?

Answer 8

Direct invasion

• Penetrating wound (iatrogenic? – joint injection)
• Intra-articular injury
• Arthroscopy

Eruption of bone abscess - see picture

Haematogenous

Infected joint replacement

• Now most common cause of septic arthritis in adult
• Staph. aureus still most common organism

Question 10

What is the differential diagnosis for someone who is presenting with symptoms of septic arthritis?

Answer 10

• Acute osteomyelitis
• Trauma
• Irritable joint
• Haemophilia
• Rheumatic fever
• Gout
• Gaucher’s disease

Question 11

What antibiotics might you use to empirically treat septic arthritis?

Answer 11

4-6 weeks

• IV Fluclox +/- rifampicin, then switch to oral
• Vancomycin if MRSA or penicillin allergic

Question 12

WHat are risk factors for the development of septic arthritis?

Answer 12

• Prosthetic implant
• Interventions (e.g., intra-articular injections)
• Underlying joint disease, especially rheumatoid arthritis
• Immunosuppressed state
• Diabetes mellitus
• Age > 80 years
• Chronic skin infections
• IV drug use

Question 13

What test is requried for definitive diagnosis of septic arthritis?

Answer 13

USS guided arthrocentesis - to distinguish between infective, inflammatory, haemorrhagic, non inflammatory causes, and culture