Bone and Joint Infections

Question 1

What are some investigations that can be done for bone and joint infections?

Answer 1

Useful blood tests = CRP, PV
Occasionally useful blood tests = blood cultures, white cell count, ESR
X-rays, technetium scan, MRI

Question 2

When does acute osteomyelitis mostly occur?

Answer 2

Post-trauma or post-operative (inoculation of infectious agent)

Question 3

How does acute osteomyelitis spread in children and the immunosuppressed?

Answer 3

Haematogenous spread

Question 4

What are some causative organisms of acute osteomyelitis?

Answer 4

Most common = Staph aureus
Haemophilus influenza in children
Also pseudomonas and enterobacteriaceace

Question 5

What are risk factors for acute osteomyelitis?

Answer 5

Smoking, diabetes (especially diabetic foot ulcers), kidney failure

Question 6

What are the symptoms of acute osteomyelitis?

Answer 6

Fever, swelling and warmth of affected joint, pain, fatigue

Question 7

How is acute osteomyelitis treated?

Answer 7

Surgery and drainage of pus may be needed, treated with antibiotics for 4-6 weeks

Question 8

How is chronic osteomyelitis diagnosed?

Answer 8

Blood tests often unhelpful, use plain x-rays and MRI

Gold standard diagnosis = positive bone cultures and histopathologic examination of bone

Question 9

What may occur in chronic osteomyelitis?

Answer 9

Bone sequestration and destruction

Involucrum = growth of new bone around dead bone

Question 10

What is the most common causative organism in chronic osteomyelitis?

Answer 10

Staph aureus

Question 11

How is chronic osteomyelitis treated?

Answer 11

By removing all pathogens and devitalised tissue, usually by surgical debridement

Question 12

How can septic arthritis be spread?

Answer 12

From inoculation, metaphyseal spread or direct haematogenous spread

Question 13

What are the symptoms of septic arthritis?

Answer 13

Swelling, redness and heat in joints that develop quickly over a few hours or days, most common in hips and knees

Question 14

What are some risk factors for septic arthritis?

Answer 14

Diabetes, IV drug users, joint prostheses, underlying joint disease

Question 15

What are the causative organisms of septic arthritis?

Answer 15

Most commonly staph aureus and haemophilus influenzae

E.coli and pseudomonas in IV drug users and elderly

Question 16

What are the investigations and treatment for septic arthritis?

Answer 16

Investigations = blood tests, synovial fluid sample, maybe MRI
Treatment = treated with antibiotics for 4-6 weeks and drainage of fluid (arthrocentesis)

Question 17

What are some examples of soft tissue infections?

Answer 17

Cellulitis and necrotising fasciitis

Question 18

How should cellulitis treated?

Answer 18

Use best guess antibiotics to cover staph and strep, often flucloxacillin and benzylpenicillin

Question 19

What are some predisposing events of necrotising fasciitis?

Answer 19

Surgical wounds, puncture wounds form IV drugs, insect bites

Question 20

What are the general treatments for soft tissue infections?

Answer 20

Debridement following biopsy, let out any pus, antibiotics may be prescribed at low maintenance dose after infection has cleared

Question 21

What is infected arthroplasty?

Answer 21

Deep infection of prosthetics, usually joint replacements

Symptoms = increased pain and stiffness of joint, swelling, fatigue, fever

Question 22

What are important questions to ask in a patient with a suspected infected arthroplasty?

Answer 22

Was there ever a wound problem?

Has the wound ever been pain free?

Question 23

What are some risk factors for an infected arthroplasty?

Answer 23

Immune deficiency or immunosuppression, diabetes, peripheral vascular disease, obesity

Question 24

What investigations can be done for infected arthroplasty?

Answer 24

CRP, joint aspiration, bone scan (technetium 99), x-ray

Question 25

How should an infected arthroplasty be treated?

Answer 25

Debridement, single staged surgery (less popular) or staged surgery (usually two staged, needs 6 weeks of follow up IV antibiotics)

Question 26

What are some elements of surgery controlled to ensure the environment is as sterile as possible?

Answer 26

Easily measured = clean air theatres, local and systemic antibiotics, duration of surgery
Difficult to measure = neat surgery, quality of hand washing, theatre discipline

Question 27

What are some ways to deliver prophylaxis?

Answer 27

Laminar flow, 24hrs antibiotics starting with induction, antibiotics in cement

Question 28

What are some antibiotics given for prophylaxis?

Answer 28

Co-amoxiclav, flucloxacillin + gentamicin, clindamycin, co-trimoxazole

Question 29

What are some common pathogens that prophylaxis is used to protect against?

Answer 29

Staph aureus, staph epidermidis (coagulase negative staph)

Question 30

What is the aim for infections occurring following joint replacement surgery?

Answer 30

Deep infection of the average joint infection should occur in less than 1% of cases

Question 31

What is the prognosis like for children with acute bone and joint diseases?

Answer 31

Generally have good outcomes