Septic Arthritis

Question 1

Define septic arthritis

Answer 1

Refers to an infection of one or more joints caused by pathogenic inoculation of microbes

Question 2

What two ways can the bacteria spread into the joint causing septic arthritis

Answer 2

Direct inoculation

OR

Via haematogenous spread

Question 3

Septic arthritis is a medical emergency.

What can occur if treatment is delayed

Answer 3

Can result in permanent joint damage and systemic sepsis

Question 4

What is the most common causative pathogen causing septic arthritis

Answer 4

Staphylococcus Aureus

Question 5

What joints are affected in septic arthritis

Answer 5

Any joint can be affected but large joints (e.g. hip and knee) are most common

Question 6

Name the two categories of septic arthritis

Answer 6

Native joint infection

Prosthetic joint infection

Question 7

Native joint infection is a type of septic arthritis.

How is it usually treated

Answer 7

Infection affecting a native joint

Management typically requires joint drainage (where appropriate) and antimicrobial therapy.

Question 8

Prosthetic joint infection is a type of septic arthritis.

How is it usually treated

Answer 8

Serious complication of prosthetic joint replacement.

Surgical intervention in addition to antimicrobial therapy is commonly required.

Question 9

Name some of the risk factors for septic arthritis

Answer 9

Extremes of age (children and elderly)

Prosthetic joint

Underlying joint disease

Immunodeficiency/Immunocompromised

IVDU

Question 10

Which causative bacteria is most common in IVDU

[septic arthritis]

Answer 10

Pseudomonas aeruginosa

Question 11

Which causative bacteria is most common in young, sexually active individuals

[septic arthritis]

Answer 11

Neisseria gonorrhoeae

Question 12

Describe the pathogenesis of septic arthritis

Answer 12

Arises when pathogens (most commonly bacteria) enter the synovium

Pathogens can spread to the synovium either by haematogenous spread or by direct inoculation

Haematogenous spread is the most common mechanism. It is the result of a bacterium located in the bloodstream seeding into the joint

Direct inoculation can occur during surgery, secondary to injury e.g. bites, wounds.

Question 13

Bacteria can spread into the joint causing septic arthritis by either direct inoculation or via haematogenous spread.

Which is the most common mechanism

Answer 13

Haematogenous spread

Question 14

Bacteria can spread into the joint causing septic arthritis by either direct inoculation or via haematogenous spread.

Describe some of the ways direct inoculation occurs

Answer 14

During surgery

Secondary to injury e.g. bites, wounds

Question 15

Describe the clinical features of septic arthritis

Answer 15

Hot, swollen acutely painful joint with restriction of movement

Usually only affects a single joint

Systemically symptoms e.g. fever, lethargy, sepsis

Question 16

What are the two key investigations used in septic arthritis

Answer 16

• Joint aspiration – synovial fluid sample
• Bloods and culture

Identifying the underlying organism and resistance pattern is key

Question 17

When should joint aspiration and bloods and cultres be done

Answer 17

As soon as there is clinical suspicion.

Obtained prior to empirical IV antibiotics

Question 18

What is the key treatment in septic arthritis

Answer 18

IV antibiotics

Question 19

Alongside IV antibiotics, what other things can be used to aid the management of septic arthritis

Answer 19

Considering joint washout under general anaesthetic

Physiotherapy after acute infection resolves

Question 20

In a patient with a native joint, what is the first line antibiotics of choice for treating septic arthritis

Answer 20

Flucloxacillin plus rifampicin

Remember to always follow local guidelines though

Question 21

In a patient with a prosthetic joint, what is the first line antibiotics of choice for treating septic arthritis

Answer 21

If prosthetic joint use vancomycin instead of flucloxacillin

Vancomycin plus rifampicin

Question 22

What is the normal course of antibiotics for treating septic arthritis

Answer 22

Continue for 3-6 weeks

Question 23

What patients should be referred to orthopaedics for septic arthritis management

Answer 23

Those with Prosthetic joints

Or those in which the septic joint is inaccessible e.g. hip

Question 24

Name 3 potential complications of septic arthritis (if left untreated)

Answer 24

Osteomyelitis (infection of the bones)

Arthritis

Ankylosis fusion (fusing of the bones)