BONE and JOINT INFECTIONS

Question 1

What is osteomyelitis?

Answer 1

Inflammatory process of bone secondary to bacterial infection

May involve periosteum, medullary cavity, compact, cancellous bone

Question 2

What are the common routes of infection for osteomyelitis?

Answer 2

• Haematogenous spread
• Exogenous (direct or contiguous)

Most common in children is haematogenous; often polymicrobial in adults

Question 3

What is the most common route of infection?

Answer 3

Haematogenous (most common in children)

Question 4

Why is Haematogenous most common in children?

Answer 4

Due to vascular stasis at growth plates
- monomicrobial

Question 5

What is involved in the exogenous route of infection?

Answer 5

Direct (Entry to bone from fracture ect.)

Contiguous (Spread from local infection)
- polymicrobial

Question 6

Haemotagenous and exogenous are most susceptible to?

Answer 6

Gram-negatives, E. coli, S. aureus

Question 7

What is the most common bacterial cause of osteomyelitis in children?

Answer 7

S. aureus

Responsible for 90% of infections in children

Question 8

What is the treatment for S. Aureus

Answer 8

Flucloaxacillin unless MRSA then Vancomycin

Question 9

What is the typical site of osteomyelitis infection in children?

Answer 9

Metaphysis of long bones

In adults, common in foot bones (especially diabetics) and vertebrae & pelvis

Question 10

What diagnostic methods are used for osteomyelitis?

Answer 10

• Culture & Gram stain of pus aspirates
• Bone biopsy
• Imaging (X-ray, CT, MRI)
• Blood culture

Blood culture useful in haematogenous infection

Question 11

What is the initial treatment duration for osteomyelitis?

Answer 11

4-6 weeks IV + 2-4 weeks oral

Empiric treatment is adjusted once sensitivities are known

Question 12

What is septic arthritis?

Answer 12

Invasion of joint by infectious agent causing arthritis

Can be caused by bacteria, viruses, or fungi

Question 13

What is the most common cause of septic arthritis?

Answer 13

S. aureus
(60-80%)

Neisseria gonorrhoeae is also a significant cause in young sexually active individuals

Question 14

What are the risk factors for septic arthritis?

Answer 14

• Previously damaged joints
• Joint replacement surgery
• IDU
• Immunosuppression
• Male
• Age (>65 years old)

56% of infections occur in males

Question 15

What are the clinical symptoms of septic arthritis?

Answer 15

• Acute onset of inflammation & swelling
• Loss of joint mobility
• Arthralgia

Knee is the most common site in adults

Question 16

What is the typical treatment for septic arthritis?

Answer 16

• IV empirical therapy
• Change when sensitivities known
• 2-4 weeks IV + 1-2 weeks oral

Surgical aspiration/drainage may be required

Question 17

What is the most common complication of osteomyelitis?

Answer 17

Septic arthritis

Other complications include DVT, sepsis, and chronic/recurrent osteomyelitis

Question 18

What are the classifications of osteomyelitis based on duration?

Answer 18

• Acute
• Subacute
• Chronic

Classification helps in understanding the disease progression

Question 19

What is Brodie’s abscess?

Answer 19

Localized osteomyelitis with few clinical signs

Often presents with little to no pain and may persist for years

Question 20

What is the significance of imaging studies in diagnosing osteomyelitis?

Answer 20

X-rays may initially appear normal; changes visible after 10-14 days

MRI is useful for early diagnosis

Question 21

What is the role of Gram stain in the diagnosis of osteomyelitis?

Answer 21

Provides direct empiric antimicrobial guidance

Culture may be negative in 25% of cases

Question 22

What is the treatment for MRSA in osteomyelitis?

Answer 22

Vancomycin

Flucloxacillin is used for S. aureus

Question 23

What is the most common cause of septic arthritis in younger sexually active individuals?

Answer 23

Neisseria gonorrhoeae

Accounts for a significant percentage of cases in this demographic

Question 24

What are biofilms in the context of septic arthritis?

Answer 24

A layer of microorganisms that can form on joint prostheses

They complicate infections and are associated with S. aureus and S. epidermidis

Question 25

What is the typical appearance of synovial fluid in septic arthritis?

Answer 25

Turbid, yellow, decreased viscosity ## Footnote Indicates infection and inflammation in the joint

Question 26

What is the recommended empirical treatment for septic arthritis caused by S. aureus?

Answer 26

Flucloxacillin ## Footnote Treatment may vary based on the patient's history and infection type

Question 27

What is the common presentation of osteomyelitis in children?

Answer 27

Severe pain, oedema, erythema, fever, malaise ## Footnote Infants may show less dramatic symptoms

Question 28

What factors contribute to the pathogenesis of osteomyelitis?

Answer 28

* Inflammation * Ischaemia & necrosis * Osteolysis * Suppuration ## Footnote These factors contribute to bone damage and infection progression

Question 29

What is Sequestrum?

Answer 29

Devitalised bone

Question 30

What is supperation?

Answer 30

Pus formation in bone

Question 31

What is osteomyelitis?

Answer 31

Inflammatory process of bone due to infection, may involve periosteum, medullary cavity, compact, and cancellous bone. ## Footnote Classification includes acute, subacute, and chronic based on duration.

Question 32

What are the two main routes of infection for osteomyelitis?

Answer 32

* Haematogenous * Exogenous ## Footnote Haematogenous is most common in children, while exogenous involves direct inoculation of bone.

Question 33

Which bacteria are most commonly associated with haematogenous osteomyelitis in children?

Answer 33

* S. aureus * S. pyogenes * S. pneumoniae * E. coli ## Footnote Neonates are also affected by S. aureus, S. agalactiae, and E. coli.

Question 34

What are some risk factors for osteomyelitis?

Answer 34

* Immunosuppression * Diabetes * Steroids * Cancer * Asplenia * Age (children & elderly) * PVD * Smoking * IDU * Chronic joint disease * Recent bone surgery/joint replacement/bone trauma ## Footnote IDU refers to intravenous drug use.

Question 35

What are common clinical symptoms of osteomyelitis in children?

Answer 35

* Severe pain * Oedema * Erythema * Pseudoparalysis * Fever * Malaise * Nausea * Vomiting ## Footnote Symptoms may be less dramatic in infants.

Question 36

What is the most common cause of septic arthritis?

Answer 36

S. aureus, accounting for 60-80% of cases. ## Footnote Other causes include S. epidermidis, streptococci, Neisseria gonorrhoeae, and gram-negative bacteria.

Question 37

True or False: Septic arthritis can be caused by bacteria, fungi, or viruses.

Answer 37

True ## Footnote The disease can be acute or chronic, focusing on acute bacterial infections.

Question 38

What is the treatment duration for osteomyelitis?

Answer 38

IV (4-6 weeks) followed by oral (2-4 weeks) therapy. ## Footnote Treatment may change when sensitivities are known.

Question 39

What diagnostic methods are used for osteomyelitis?

Answer 39

* Aspiration of pus from bone * Gram stain * Culture * Bone biopsy * Imaging studies (X-ray, CT, MRI) * Raised CRP ## Footnote ~50% of blood cultures are positive in haematogenous osteomyelitis.

Question 40

What is a common complication of osteomyelitis?

Answer 40

* Septic arthritis * DVT * Sepsis * Metastatic infection * Chronic/recurrent osteomyelitis * Altered bone growth * Pathological fracture ## Footnote These complications can arise due to the progression of the infection.

Question 41

Fill in the blank: The most common site for septic arthritis in adults is the _______.

Answer 41

Knee ## Footnote The hip is the most common site in children.

Question 42

What are the common imaging studies used for diagnosing osteomyelitis?

Answer 42

* X-ray * CT * MRI * Bone scans ## Footnote X-rays may take 10-14 days to show changes.

Question 43

What is Brodie’s abscess?

Answer 43

Localized osteomyelitis with few clinical signs and little to no pain, may persist for years. ## Footnote It is often associated with S. aureus.

Question 44

What is the typical treatment for septic arthritis?

Answer 44

* IV empirical therapy * Change when sensitivities known * Surgical aspiration/drainage * Removal of prosthesis/debridement ## Footnote Treatment is similar to that of osteomyelitis.

Question 45

What is the role of Gram stain in diagnosing septic arthritis?

Answer 45

Direct empiric antimicrobials based on the appearance of the aspirate. ## Footnote Non-Neisseria cases are usually culture positive unless antibiotics were administered beforehand.

Question 46

What is the typical clinical presentation of septic arthritis?

Answer 46

* Acute onset of inflammation and swelling * Joint effusion * Loss of joint mobility * Arthralgia ## Footnote Knee and hip are the most affected joints.

Question 47

What are the common pathogens involved in chronic osteomyelitis?

Answer 47

* S. aureus * S. epidermidis * Streptococci * Gram-negatives * Anaerobes ## Footnote Granulomatous infections can also occur with pathogens like TB and syphilis.

Question 48

What is the significance of biofilms in septic arthritis?

Answer 48

S. aureus forms biofilms in early-onset infections (within 3 months post-implant), while S. epidermidis is associated with late-onset infections. ## Footnote Biofilms contribute to the increasing incidence of septic arthritis after joint surgery.