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Locomotor 2 > Bone and Joint Infections > Flashcards

Bone and Joint Infections Flashcards

1
Q

what is septic arthritis

A

Septic arthritis, also known as joint infection or infectious arthritis, is the invasion of a joint by an infectious agent resulting in joint inflammation.

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2
Q

how many people experience septic arthritis

A

8 per 100,000 in UK, higher in developing countries

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3
Q

How old are the people experiencing septic arthritis

A

45% are older than 65 years

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4
Q

What are the types of septic arthritis

A

Mono-articular 90%

Poly-articular 10%

can also have acute and chronic

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5
Q

what is more common in septic arthritis mono-articular or poly-articular

A

Mono-articular 90%

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6
Q

describe the symptoms of acute septic arthritis

A

pyogenic

mild (60 - 80% of cases)

> 39oC (1/3rd of cases)

Limitation of joint movement

Swelling (synovial effusion)

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7
Q

describe chronic septic arthritis

A

usually non pyogenic (not pus production)

  • Can be due to TB, TB is slow growing
  • joint does not feel hot and instead it feels cold
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8
Q

What does pyogenic stand for

A

involving or relating to the production of pus.

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9
Q

Why does septic arthritis affect the elderly population more

A

45% in the elderly population this is because they have more damage to the joints and rubbing on the periosteum tearing the synovial membrane

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10
Q

what is the most common joint affected by septic arthritis

A

Knee joint

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11
Q

what is the pathogenesis for septic arthritis

A

Infective organism reaches joint via blood supply is the most common pathogenesis

  • can have direct contamination or post operative infection as well
  • can spread from muscle or connective tissue into he bone
  • untreated systemic infection
  • penetrating trauma - can have an open feature this tears the skin and allows bacteria from the skin to enter the blood stream and into the joint
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12
Q

name the common organisms that cause septic arthritis

A

Gram positive cocci
- Staphylococcus aureus
Streptococci
- Pyogenes, Pneumoniae, Group B

Gram positive bacilli
- Clostridium sp

Gram negative cocci
- Neisseria gonorrhea

Gram negative bacilli

  • Escherichia coli
  • Pseudomonas aeruginoa
  • Eikenella corrodens (human bites)
  • Haemophilus influenza (paediatric before immunization)
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13
Q

what bacteria is the most common organism to cause septic arthritis

A

Staphylococcus aureus - causes greater than 90% of cases

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14
Q

how does Staphylococcus aureus and other bacteria cause septic arthritis

A
  • release pro-inflammatory cytokines
  • bacterial cell wall proteins form a super antigen that activate immune cells that create lots of cytokines that damage the joint
  • form adhesions that allow them to spread into the bone
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15
Q

what is commonly affected by septic arthritis

A

Most commonly: knee

Also: hip, ankle, elbow

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16
Q

what joints are infrequently affected by septic arthritis

A

Infrequent: wrist, shoulder, fingers

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17
Q

what do the laboratory results show in septic arthritis

A
  • Elevated ESR
  • Neutrophilia
  • turbid or purulent
  • leukocytes > greater than 50,000mm3 = predominelty neutrophils
  • gram stain positive in one third
  • <25mg/dL glucose (much lower than serum)
  • blood culture positive in one - to two thirds
  • culture other sites such as urethra and biopsy
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18
Q

what can you see in radiology for septic arthritis

A
  • may see soft tissue swelling
  • joint capsule distension

destructive changes seen after at least two weeks

  • erosion of articular surface
  • associated tissue swelling
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19
Q

in radiology what would you see in a mycobacterial infection

A

joint space narrowing

effusion

erosions

cyst formation

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20
Q

why do you use a radiograph to look for septic arthritis

A
  • do it to rule out anything else
21
Q

what can you see in an MRI for septic arthritis

A
  • joint diffusion and swelling

- abscess of cysts filled with bacteria

22
Q

what are differential diagnosis to septic arthritis

A

acute rheumatoid arthritis

gout

chondrocalcinosis

23
Q

What is the treatment for septic arthritis

A

Drainage

  • wash out multiple times with sterile saline
  • wash it out until you get a dry tap and nothing else is coming out

Antibiotics

  • depends on Gram stain and patient background
  • IV 3-4 weeks
  • Possibly start with broad spectrum modify when Gram stain known
24
Q

what is another word of reactive arthritis

A

Reiter’s arthritis

25
Q

describe reactive arthritis (Reiter’s arthritis)

A
  • reactive or post infectious
  • common in presence of HLA-B27
  • sterile inflammatory processes - no infection takes place after infection
  • usually has extra-articular symptoms
26
Q

what HLA is reactive arthritis (Reiter’s arthritis) associated with

A

HLA-B27

27
Q

what infections does reactive arthritis (Reiter’s arthritis) usually proceed

A

Preceded by enteric or genitourinary infection

  • STI (chlamydia trachomatis)
  • Enteritis (salmonella, campylobacter etc)
28
Q

how does TB affect the joints

A

TB affects the lungs and causes lung infections with granulomas

  • these granulomas can spread out into the bone
  • tend to go to the vertebrae
29
Q

What two vertebra are commonly affected by TB

A

T10 and T11

30
Q

What is Potts disease

A

Pott disease is tuberculosis of the spine, usually due to haematogenous spread from other sites, often the lung

31
Q

What is osteomyelitis

A

Osteomyelitis is an infection that most often causes pain in the long bones in the legs.

32
Q

How does osteomyelitis spread

A
  • haematogenous spread

- contiguous spread from an infected focus

33
Q

how does osteomyelitis spread in adults versus in children

A

Acute hematogenous osteomyelitis - primarily in children

Direct trauma and contiguous focus osteomyelitis – more common in young adults

34
Q

who is spinal osteomyelitis common in

A

Spinal osteomyelitis – more common in adults over 45 years

35
Q

what is acute blood born osteomyelitis primarily in

A

children

  • epiphyseal growth plate are open and this area of bone is quickly growing and twister and therefore you have slow flow of blood through the new bone
  • children have a weaker immune system so they are more at risk
  • bones are mainly woven bone that is softer and weaker
36
Q

what are the consequences of osteomyelitis

A

area of the bone is dead in the centre
- new bone has formed around it to keep the pus and bacteria in place
-

37
Q

What are the predisposing factors factors that lead to osteomyelitis

A

Impairment of immune surveillance

  • malnutrition
  • extremes of age

impairment of local vascular supply

  • diabetes mellitus (30-40% of patients)
  • venous stasis
  • radiation fibrosis
  • sickle cell disease (0.36% of patients)
38
Q

What are the clinical features of osteomyelitis

A

Hematogenous long bone – abrupt onset of high fever (only 50% in children; less in adults)

Decreased limb movement, adjacent joint effusion (infants)

Hematogenous vertebral and chronic – insidious onset, vague complaints over 1 to 3 months

Local non-specific pain

Elevated neutrophil count (<50% of cases)

Elevated ESR

39
Q

what is a Brodies abscess

A

Lytic lesion oval in shape, surrounded by thick dense reactive sclerosis that fades into surrounding bone.
- full of pus

40
Q

What can progress to chronic osteomyelitis

A

Haematogenous and contiguous spread osteomyelitis can progress to chronic osteomyelitis

41
Q

what is the result of chondric osteomyelitis

A
  • local bone loss and persistent drainage through sinus.

- Squamous cell carcinoma and amyloidosis are rare complications

42
Q

How do you investigate osteomyelitis

A

Bone biopsy

Blood cultures
- Sinus tract culture NOT reliable

Neutrophil count,

ESR of limited value in monitoring response to treatment

Radiography (changes lag infective course by 2 weeks)

Bone scintingraphy shows the active bone that is being produced

43
Q

How do you treat osteomyelitis

A

Surgical debridement to remove dead bone
- Sequestrum

Reconstruct bone (allograft or autograft)
- New bone shell involucrum

Antibiotics for 4-6 weeks (at least 2wks IV)

44
Q

name the antibiotics that you use to treat osteomyelitis and the way in which they are given

A

Vancomycin cement beads

Flucloxacillin (gram positive)

Clindamycin (oral and foam)

Piperacillin (broad spectrum, IV, IM only)

Ciprofloxacin (broad spectrum

45
Q

where does prosthetic bone and joint infection occur

A

Occurs in osseous tissue adjacent to prosthesis
bone cement interface
bone contiguous with prosthesis (cementless devices)

46
Q

what does prosthetic bone and joint infection result from

A

local inoculation at surgery or post-op spread from wound sepsis

haematogenous spread

47
Q

what are the changes in the X ray of the prosthetic bone and joint infection

A

lucencies at bone-cement interface

changes in component position

cement fractures

Periosteal reactions

gas in joint

48
Q

how do you investigate a prosthetic bone and joint infection

A
  • X rays
  • radio-isotopes scans
  • elevated ESR, neutrophil count
  • culture of biopsy/joint fluid
49
Q

how do you manage a prosthetic bone and joint infection

A

Retain/replace prosthesis

  • simple debridement (retaining prosthesis) plus antibiotics - only successful in 20% of cases
  • removal of prosthesis, antibiotics for 6wks, re-implantation of prosthesis - 90%+ success (has no joint for 6 weeks)
  • removal of prosthesis, immediate re-implantation, antibiotics - 70%+ success
  • suppressive long term antibiotics

Locomotor 2 (30 decks)

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