Bone and joint infection

Question 1

In what ages is septic arthritis usually seen

Answer 1

Extremes of age- older than 65 or the very young

Question 2

Is it ususally mono-articular or poly-articular

Answer 2

Mono

Question 3

How does septic arthritis usually present

Answer 3

• Red
• Swelling
• Inflammation
• Fever

Question 4

What bacteria usually give a ‘cold inflammatory process’

Answer 4

Microplasma such as TB

Slow growing

Question 5

Why does septic arthritis happen more in elderly

Answer 5

More likely to have osteoarthritis- more injections/ procedures

Question 6

How do the majority of infections get to the joint capsule in septic arthritis

Answer 6

Via the blood supply

Question 7

What organism most commonly leads to septic arthritis

Answer 7

Staph aureus

Question 8

Name some other common organisms which can lead to bone/ joint infection

Answer 8

Streptococci pneumoniae/ group B. pyogenes

Question 9

How do the microorganisms lead to bone/ joint infections

Answer 9

Activation of macrophages/ T/ B cells lead to damage of the joint

Question 10

3 potential causes of bone/ joint infections

Answer 10

Previous damage to joint
Untreated systemic infection
Conditions that affects blood supply to the joint

Question 11

What is the most commonly affected joint in septic arthritis

Answer 11

Knee

Question 12

What joints are infrequently affected by septic arthritis

Answer 12

Wrist, shoulder, fingers

Question 13

Describe the lab findings for somebody with septic arthritis

Answer 13

• Elevated ESR

- Neutrophilia (esp in children)

Question 14

How will synovial fluid appear in bone/ joint infection

Answer 14

Turbid/ purulent
Gram stain positive
Low glucose level
Leukocytes

Question 15

In what % of septic arthritis cases are blood culture positive

Answer 15

1/3

Question 16

Describe the radiological findings of somebody with septic arthritis

Answer 16

• Initially not useful- may see some soft tissue swelling
• Joint capsule distension depending on
• Erosition of articular cartilage and soft tissue swelling

Question 17

When do you see destructive changes radiologically in somebody with septic arthitis

Answer 17

After 2 weeks

Question 18

What do you see radiologically in myobacterial infection?

4

Answer 18

Joint space narrowing
Effusion
Erosion
Cyst formation

Question 19

Differential diagnoses for septic arthritis

Answer 19

Acute rheumatoid arthritis
Gout/ pseudogout
Chondrocalcinosis

Question 20

How do you treat septic arthritis

Answer 20

Drainage

Broad spectrum antibiotics asap and then modify depending on gram stain

Question 21

How long will septic arthritis patients be on IV antibiotics for

Answer 21

3-4 weeks

Question 22

When does reactive arthritis occur

Answer 22

Post infection

Question 23

How do osteomyeltitis usually spread

Answer 23

Haemotagenous spread

Question 24

What usually causes osteomyelitis in adults

Answer 24

Trauma (open fracture)

Question 25

What are the consequences of osteomyelitis

Answer 25

Abcess on the metaphyseal side of the growth plate | Makes bone around the abcess to try and keep it from the healthy tissue

Question 26

What are the 2 general predisposing factors for osteomyelitis

Answer 26

Impairment of immune surveillance | Impairment of local vascular supply

Question 27

What impairments of the immune surveillance can lead to osteomyelitis

Answer 27

Malnutrition | Extremes of age

Question 28

What impairments of vascular supply can lead to osteomyelitis

Answer 28

Diabetes Venous statis Radiation fibrosis Sickle cell disease

Question 29

Describe the clinical features of osteomyelitits

Answer 29

``` Hametogenous long bone Abrupt onset of fever Decreased limb movement Local non specific pain Elevated neutrophil and ESR ```

Question 30

What is the result of chronic osteomyelitits

Answer 30

Local bone loss and persistent draingage through the sinus

Question 31

How do you investigate chronic osteomyelitis

Answer 31

Bone biopsy Blood cultures Neutrophil count ESR

Question 32

How is osteomyelitis managed surgically

Answer 32

Debirdement to remove teh seqeustrum ( dead bone) | Reconstruct the bone

Question 33

How long must a person be on antibiotics for chronic osteomyelitis

Answer 33

4-6 weeks

Question 34

What is involcrum

Answer 34

The new bone that has been remodelled

Question 35

How does prosthetic bone and joint infection occur

Answer 35

- Occurs in the osteous tissue adjacent to prosthesis at the bone/ cement interface - Results from local inoculation at surgery or post-op spread from wound sepsis