Bone and Joint Infections

Question 1

5 cardinal features of inflammation?

Answer 1

Rubor (redness)
Calor (heat)
Dolor (pain)
Tumor (swelling)
Functio laesa (loss of function)

Question 2

Specimens for diagnosis in bone and joint infection?

Answer 2

If indicated, blood culture, joint aspirate, wound swab, etc

Question 3

Blood tests for bone and joint infection?

Answer 3

• CRP, PV (non-specific marker of inflammation
• WCC
• ESR

Question 4

Imaging for bone and joint infections?

Answer 4

X-rays can show, e.g: bone abscesses

Technetium (bone) scan - osteoblast reaction at infected sites lights up but this is non-specific

MRI (can show assoc. soft tissue issues)

Question 5

5 types of bone and joint infections?

Answer 5

1. Acute osteomyelitis
2. Chronic osteomyelitis
3. Septic arthritis
4. Soft tissue infections
5. Infected arthroplasty

Question 6

Situations where acute osteomyelitis can occur?

Answer 6

Mostly occurs post-trauma/with open fractures (esp. if an inadequate operation is done)

Children or immunosuppressed individuals (haematogeneous spread)

Question 7

Pathogens in acute osteomyelitis?

Answer 7

Staph. aureus (most common)

In children, consider Haemophilus

However, any bacterium can cause this

Question 8

Treatment of acute osteomyelitis?

Answer 8

Once diagnosed, antibiotics and, if there is pus, drainage

Question 9

Describe chronic osteomyelitis

Answer 9

Pus spreads into the bone’s blood vessels, impairing their flow, and areas of devitalized infected bone form

New bone forms around the necrotic area (called involucrum)

Question 10

Diagnosis of chronic osteomyelitis?

Answer 10

Blood tests are not very useful

Plain X-rays (can show bone abscesses as an area of lucency with sclerosis around it) and MRI

Question 11

Treatment of chronic osteomyelitis?

Answer 11

Not every patient requires surgery, as bacteria can become dormant for decades at a time

Open surgery is generally used, whereby the involucrum is opened

Question 12

Mechanisms by which septic arthritis occurs?

Answer 12

1. From inoculation
2. From metaphyseal spread
3. Direct haematogeneous spread

Question 13

Importance of septic arthritis diagnosis?

Answer 13

Emergency, as pus can destroy cartilage and the joint

Question 14

Treatment of septic arthritis?

Answer 14

Drain pus + antibiotics

If the joint is prosthetic, it can be removed and replaced at a later date

Question 15

Types of soft tissue infections?

Answer 15

Cellulitis (use antibiotics that cover Staph. and Strep. like Flucloxacillin and Benzylpenicillin)

Necrotising fasciitis

Question 16

Presentation of necrotising fasciitis?

Answer 16

Tend to present with septic shock and are disproportionately unwell; if a hand is pressed on the skin, it feels like bubble wrap underneath

Question 17

Risk factors for necrotising fasciitis?

Answer 17

Immunosuppression
Cancer
Injury, e.g: with exposure to soil

Question 18

Treatment of necrotising fasciitis?

Answer 18

Identify the pathogen (biopsy and debridement tend to occur together)

Surgical removal of dead tissue or foreign body

Drainage of pus

Target antibiotics (do not wait to ID the pathogen)

Question 19

Describe infected arthroplasty

Answer 19

Infected prosthetic joint (a type of DEEP infection); this is a problem that can never be completely cured

Often caused by Staph. epidermidis (produces slime/biofilms)

Question 20

Hx questions with infected arthroplasty?

Answer 20

Was there ever a wound problem?

Has it ever been pain free? (if not, this is a worrying sign)

Question 21

Ix for infected arthroplasty?

Answer 21

CRP

Joint aspiration

Bone technetium scan

X-ray

Question 22

Describe sinuses in infected arthroplasty

Answer 22

A sinus tract can communicate with the infected arthroplast (producing a line between cement and bone on Ix and also filling with dye)

Question 23

Treatment of infected arthroplasty?

Answer 23

Drainage of pus

Question 24

Prophylaxis of infected arthroplasty?

Answer 24

Systemic antibiotics for 24 hours starting with induction, usually co-amoxiclav, and local antibiotics (e.g: in cement)

Clean air theatre and controlled duration of surgery