Musculoskeletal Infections

Question 0

Define osteomyelitis

Answer 0

Infection of bone (marrow spaces)

Question 1

Describe Cellulitis

Answer 1

Infection of skin, subcutaneous fat, or connective tissue (tendons/lig/muscle)

Question 2

Define septic arthritis

Answer 2

Infection of joint (synovial) tissue, articular surfaces

Question 3

Most at risk for musculoskeletal infections (6)

Answer 3

Immunosuppressed
Diabetics
Post-surgical
Vascular insufficiency
Sickle-cell anemia
IV drug users

Question 4

Drug addicts are prone to infections at what unusual sites?

Answer 4

"S" joints:
Spine
Sacroiliacs
Symphysis pubis
Sternoclavicular

Question 5

What is the MC organism for musculoskeletal infections?

Answer 5

Staphylococcus aureus (90%)

Question 6

Common modes of infection. (6)

Answer 6

Trauma/post-surgical
UTI
Pneumonia
Skin infections
Cellulitis
Heal sticks in infants

Question 7

Routes of infectious dissemination (4)

Answer 7

Hematogenous (MC )
Direct extension
Direct implantation
Postoperative

Question 8

Which group is more prone to an acute infectious process?

Fever, chills, pain, swelling, loss of function, elevated WBC count

Answer 8

Infants and young adults

Question 9

Which group is more prone to an insidious infectious process.
(Fever, malaise, edema, erythema and pain)

Answer 9

Adults

Question 10

Supperative osteomyelitis is MC in M/F and what age?

Answer 10

Males 3:1

Age 2-12 years

Question 11

MC location musculoskeletal infectious? (5)

Answer 11

Knee
Hip
Ankle (distal tibia)
Shoulder
Spine

Question 12

What are the two major categories of infection, and what is the MC causative organism?

Answer 12

Superlative - staph aureus

Non-supperative - mycobacterium tuberculosis

Question 13

Clinical features of acute infection? (5)

Answer 13

Edema
Lymphadenopathy 
Warm skin
Cellulitis
Joint pain

Question 14

What are the 4 radiographic stages

Answer 14

Latent (1-10 days)
Early (10-21 days)
Middle (weeks)
Late (months)

Question 15

Which radiographic stage?

Soft tissue edema, osteopenia

Answer 15

Early stage

Question 16

Which radiographic stage?
Permeative or moth eaten destruction crossing anatomical barriers,
Codman’s triangle

Answer 16

Middle stage

Question 17

Which radiographic stage?

Cortical destruction, involcrum, cloaca, sequestrum, sclerosis, debris, ankylosis, loss of joint space.

Answer 17

Late stage

Question 18

Define sequestrum?

Answer 18

Chalky, white area representing isolated dead bone.

Cortical and Medullar infarcts

Question 19

Define involcrum?

Answer 19

“Bony collar” -chronic periosteal response

Question 20

Define cloaca?

Answer 20

Draining sinus (MC with chronic disease)

Question 21

The ulcerative channel with malignant transformation is known as_________?

Answer 21

Marjolin’s ulcer.

This is a rare complication related to squamous cell carcinoma and the cloacal channel

Question 22

What is the most common site for a spinal infection?

Answer 22

Lumbar spine

Question 23

What joints have a higher incidence of spinal infection with IV drug users?

Answer 23

SI joints

Question 24

What are the radiographic features of a spinal infection? (4)

Answer 24

Widening of RPI Widening of RTI Paraspinal line deflection Psoas abcess

Question 25

<20 years old, where does spinal infection start and where does it go?

Answer 25

Starts in the disc and and spreads to adjacent bodies

Question 26

>20 years old (adults), where does spinal infection start and where does it go?

Answer 26

Starts in the anterior vertebral endplates then to the disc with vertebral collapse and soft tissue paraspinal mass.

Question 27

What are the features of septic arthritis? (5)

Answer 27

``` Joint effusion juxtaarticular osteoperosis erosions joint space loss Lyric destruction crossing joint space ```

Question 28

TDD of septic arthritis? | How much difference from opposite joint?

Answer 28

TDD > 11mm | > 2mm from opposite joint

Question 29

Unilateral sacroilitis is MC linked toinfection or tumor?

Answer 29

Infection

Question 30

RTI interspace________ | RPI interspace _________

Answer 30

``` RTI = 22mm RPI = 7mm ```

Question 31

How much bone loss before detected on plain film radiography?

Answer 31

40-60% loss

Question 32

With bone scans, what is tagged with 1. Technetium 2. Gallium 3. Indium

Answer 32

Technetium - non-specific Gallium - tagged RBC Indium - tagged WBC

Question 33

What are the advantages for CT?

Answer 33

Earlier detection than plain film. | Reaches hard to see areas (spine, pelvis, sternum).

Question 34

What are the findings on CT for osteomyelitis?

Answer 34

Increased marrow density, Sclerosis, Demineralization, Periosteal reaction

Question 35

Osteomyelitis has a decreased signal on ______ and an increased signal on ______ MRI. What is the sensitivity % What is the specificity %

Answer 35

Decreased - T1, Increased - T2, Sensitivity: 92-100% Specificity: 89-100%

Question 36

Treatments for osteomyelitis? (3)

Answer 36

Antibiotics Debridement Surgical drainage

Question 37

Tuberculosis AKA: (3)

Answer 37

Nonsuppurative osteomyelitis Pott's disease Mycobacterium tuberculosis

Question 38

MC cause of infection-related death worldwide, 15 million infected in USA, Found in Egypt > 5000 years ago, Kings disease

Answer 38

Tuberculosis (non-suppurative)

Question 39

Secondary tuberculosis involves what system of the body.

Answer 39

Skeletal system

Question 40

What is the most common location for secondary tuberculosis?

Answer 40

Thoracolumbar junction. | Usually involves weight-bearing joints, MC multiple levels

Question 41

Multiple level paraspinal masses, and cold abscesses with Ca+ are associated with?

Answer 41

Tuberculosis

Question 42

Tuberculosis clinical: TB skin test is + in what % | Chest film is + for granulomas in what %

Answer 42

TB skin test 90-100% | Granulomas 50%

Question 43

Juxtarticular osteoporosis Marginal erosions And slow joint space loss, All three combined are known as?

Answer 43

Phemister's triad