L4 - Clinical Investigatoins - Bone, Joint, Soft Tissue

Question 1

If bacteremia or sepsis is suspected what test should be performed?

Answer 1

Blood culture

Question 2

What procedure should be performed to diagnose a septic joint or septic arthritis?

Answer 2

Joint arthrocentesis to make a diagnosis if there are no contraindications

Question 3

What are examples of non-gonococcal septic joint DDx?

Answer 3

Gonoccocal arthritis 
Gout or pseudo gout 
Knee trauma 
RA
Rheumatic fever (rare but still on boards) 
Adult Still’s dz 
Lyme dz

Question 4

What are examples of gonoccoal septic joint DDx?

Answer 4

Endocarditis
Sacroidosis
Meningococcemia

Question 5

What are inflammatory examples for acute mono arthritis DDx?

Answer 5

Infection
Crystal induced (gout or pseudo gout)
Reactive artists
Seronegative sponyloarthropathy, CT dz

Question 6

What are non-inflammatory examples for acute mono arthritis DDx?

Answer 6

Trauma
Non traumatic bleeding (coagulopathy)
Sickle cell crisis

Question 7

Which studies should be considered for evaluation of a septic joint?

Answer 7

Synovial fluid WBC count
Synovial fluid gram stain
Synovial fluid culture
Crystals

Question 8

The likelihood of septic arthritis is directly related to what?

Answer 8

The WBC count

Counts >50k and especially 100k suggest septic arthritis

Question 9

A synovial fluid WBC count <20k suggests what?

Answer 9

Against septic arthritis

Question 10

Crystal arthritis (acute gout flare) can have a similarly high WBC count and commonly mimics what?

Answer 10

Septic arthritis

Question 11

What is a synovial fluid gram stain?

Answer 11

A positive gram stain confirms the diagnosis of septic arthritis but is only positive in 50% of the cases therefore a negative gram stain doesnt rule out septic arthritis

Question 12

What is a synovial fluid culture?

Answer 12

In cases of non gonococcal septic arthritis the synovial fluid culture is positive over 60% of the time

Question 13

What are crystals?

Answer 13

The presence of crystals in synovial fluid suggests crystal arthritis
Pts with crystal arthropathy (gout) can also develop concurrent septic arthritis
The presence of crystals on arthrocentesis doesn’t exclude septic Arthritis

Question 14

What are the three types of osteomyelitis?

Answer 14

Hematogenous osteomyelitis
Vertebral osteomyelitis
Non-hematogenous osteomyelitis

Question 15

What is hematogenous osteomyelitis?

Answer 15

Develops in the setting of bacteremia (e.g. endocarditis or another endovascular infection)

Question 16

What is vertebral osteomyelitis?

Answer 16

Develops due to hematogenous spread, local tissue invasion (e.g. from psoas abscess) or direct inoculation after a procedure

Question 17

What is non-hematogenous osteomyelitis?

Answer 17

Develops in the setting of poor wound healing such as diabetic foot ulcers and sacral decubitus ulcers followed by direct inoculation from the skin and soft tissue to the exposed bone

Question 18

What are some DDx for osteomyelitis?

Answer 18

Cellulitis 
Septic arthritis 
Gout 
Diabetic or arterial insufficiency ulcer 
Tuberculous or mycotic bone infection 
Rheumatic fever 
Metastatic cancer 
Multiple myeloma 
Avascular necrosis

Question 19

What is the most sensitive imaging modality of osteomyelitis?

Answer 19

MRI

Question 20

What are the two ways to make a diagnosis of osteomyelitis?

Answer 20

Definitive diagnosis with bone biopsy
-in general open bone biopsy has a higher diagnostic yield than needle biopsy
An inferred diagnosis with a combination of clinical features (e.g. imaging findings, positive blood cultures)

Question 21

What is sporotrichosis?

Answer 21

A relatively rare infection caused by the fungus sporothrix
Occurs when the fungus gets into the skin via small cut, scrape or puncture, such as from a rose thorn
Rose gardeners dz, rose pickers dz

Question 22

What is the most common form of sporothrichosis?

Answer 22

Cutaneous sporotrichosis
Often found on the hand and arm of someone who has been handling contaminated plant materials
Sx usually appear between 1-12 weeks after infection

Question 23

What is the progression of sx for sporotrichosis?

Answer 23

A small painless pink, red or purple bump forms where the fungus entered the skin
The bump gets bigger an starts to look like an open sore
More bumps or sores might appear in the near vicinity of the original bump