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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
describe reactive arthritis (Reiter's arthritis)
- 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
what HLA is reactive arthritis (Reiter's arthritis) associated with
HLA-B27
27
what infections does reactive arthritis (Reiter's arthritis) usually proceed
Preceded by enteric or genitourinary infection - STI (chlamydia trachomatis) - Enteritis (salmonella, campylobacter etc)
28
how does TB affect the joints
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
What two vertebra are commonly affected by TB
T10 and T11
30
What is Potts disease
Pott disease is tuberculosis of the spine, usually due to haematogenous spread from other sites, often the lung
31
What is osteomyelitis
Osteomyelitis is an infection that most often causes pain in the long bones in the legs.
32
How does osteomyelitis spread
- haematogenous spread | - contiguous spread from an infected focus
33
how does osteomyelitis spread in adults versus in children
Acute hematogenous osteomyelitis - primarily in children Direct trauma and contiguous focus osteomyelitis – more common in young adults
34
who is spinal osteomyelitis common in
Spinal osteomyelitis – more common in adults over 45 years
35
what is acute blood born osteomyelitis primarily in
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
what are the consequences of osteomyelitis
area of the bone is dead in the centre - new bone has formed around it to keep the pus and bacteria in place -
37
What are the predisposing factors factors that lead to osteomyelitis
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
What are the clinical features of osteomyelitis
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
what is a Brodies abscess
Lytic lesion oval in shape, surrounded by thick dense reactive sclerosis that fades into surrounding bone. - full of pus
40
What can progress to chronic osteomyelitis
Haematogenous and contiguous spread osteomyelitis can progress to chronic osteomyelitis
41
what is the result of chondric osteomyelitis
- local bone loss and persistent drainage through sinus. | - Squamous cell carcinoma and amyloidosis are rare complications
42
How do you investigate osteomyelitis
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
How do you treat osteomyelitis
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
name the antibiotics that you use to treat osteomyelitis and the way in which they are given
Vancomycin cement beads Flucloxacillin (gram positive) Clindamycin (oral and foam) Piperacillin (broad spectrum, IV, IM only) Ciprofloxacin (broad spectrum
45
where does prosthetic bone and joint infection occur
Occurs in osseous tissue adjacent to prosthesis bone cement interface bone contiguous with prosthesis (cementless devices)
46
what does prosthetic bone and joint infection result from
local inoculation at surgery or post-op spread from wound sepsis haematogenous spread
47
what are the changes in the X ray of the prosthetic bone and joint infection
lucencies at bone-cement interface changes in component position cement fractures Periosteal reactions gas in joint
48
how do you investigate a prosthetic bone and joint infection
- X rays - radio-isotopes scans - elevated ESR, neutrophil count - culture of biopsy/joint fluid
49
how do you manage a prosthetic bone and joint infection
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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