Septic arthritis

Question 1

Define septic arthritis?

Answer 1

Acute joint inflammation resulting from intra-articular infection (infection of cartilage and synovial fluid)

Can destroy a joint in under 24h

Usually affects knee

Question 2

outline the aetiology of septic arthritis

Answer 2

pathogenic inoculation of micro-organisms into the joint, either directly or by the haematogenous route.

Question 3

what are the risk factors for septic arthritis?

Answer 3

Recent orthopaedic procedures

Osteomyelitis

Diabetes mellitus

Rheumatoid arthritis

Prosthetic joints– infection here is particularly difficult to treat

Immunosuppression

Alcoholism

IV drug use

History of cutaneous ulcers

Question 4

what are the common causative bacterial organisms for septic arthritis?

Answer 4

All ages

• Staphylococcus aureus
• TB(should be suspected in immunocompromised)

< 4 yrs

• Streptococcuspneumoniae
• Streptococcus pyogenes
• Neisseria meningitidis
• Gram-negative rods

16-40 yrs

• Neisseria gonorrhoeae

Question 5

which viruses cause septic arthritis?

Answer 5

Rubella

Mumps

Hepatitis B

Parvovirus B19

Question 6

which fungi cause septic arthritis?

Answer 6

Candida

Question 7

summarise the epidemiology of septic arthritis?

Answer 7

Most common in CHILDREN and the ELDERLY

Question 8

what are the presenting symptoms of septic arthritis?

Answer 8

Sudden onset

Fever

Excruciating joint pain

Joint redness, swelling, tenderness and loss of joint function

Usually a monoarthropathy (usually affecting one large joint)

• NOTE: it may cause a polyarthropathy in the immunosuppressed

Tuberculous arthritis develops more slowly and is more chronic

Question 9

what are the signs of septic arthritis on physical examination?

Answer 9

Painful, hot, swollen

Immobile joint

Erythema

Severe pain prevents passive movement

Pyrexia

Look for signs of aetiology

Question 10

what are the appropriatet investigations for reactive arthritis?

Answer 10

URGENT JOINT ASPIRATION- SO YOU CAN START AB THERAPY

bloods

plain joint radiographs- may reveal degenerative changes

MRI scan- useful for detecting osteomyelitis

Question 11

what is seen in the joint aspiration in septic arthritis?

Answer 11

IMPORTANT- SO YOU CAN START AB THERAPY

URGENT GRAM STAIN

In infective arthritis, the aspirate will be grossly purulent- low viscosity turbid yellow

Synovial WCC - elevated

Send synovial fluid for MC&S

• Microscopy - rule out crystal arthritis

PCR may be used if a viral cause is suspected

Performed under USS guidance if hip sepsis is suspected

Question 12

Describe the bloods in septic arthritis?

Answer 12

FBC - high WCC, high neutrophils

High CRP and ESR

Blood cultures - MC&S

Viral serology may be useful

Question 13

describe the management septic arthritis?

Answer 13

AB + JOINT LAVAGE