L4 - Clinical Investigatoins - Bone, Joint, Soft Tissue Flashcards
If bacteremia or sepsis is suspected what test should be performed?
Blood culture
What procedure should be performed to diagnose a septic joint or septic arthritis?
Joint arthrocentesis to make a diagnosis if there are no contraindications
What are examples of non-gonococcal septic joint DDx?
Gonoccocal arthritis Gout or pseudo gout Knee trauma RA Rheumatic fever (rare but still on boards) Adult Still’s dz Lyme dz
What are examples of gonoccoal septic joint DDx?
Endocarditis
Sacroidosis
Meningococcemia
What are inflammatory examples for acute mono arthritis DDx?
Infection
Crystal induced (gout or pseudo gout)
Reactive artists
Seronegative sponyloarthropathy, CT dz
What are non-inflammatory examples for acute mono arthritis DDx?
Trauma
Non traumatic bleeding (coagulopathy)
Sickle cell crisis
Which studies should be considered for evaluation of a septic joint?
Synovial fluid WBC count
Synovial fluid gram stain
Synovial fluid culture
Crystals
The likelihood of septic arthritis is directly related to what?
The WBC count
Counts >50k and especially 100k suggest septic arthritis
A synovial fluid WBC count <20k suggests what?
Against septic arthritis
Crystal arthritis (acute gout flare) can have a similarly high WBC count and commonly mimics what?
Septic arthritis
What is a synovial fluid gram stain?
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
What is a synovial fluid culture?
In cases of non gonococcal septic arthritis the synovial fluid culture is positive over 60% of the time
What are crystals?
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
What are the three types of osteomyelitis?
Hematogenous osteomyelitis
Vertebral osteomyelitis
Non-hematogenous osteomyelitis
What is hematogenous osteomyelitis?
Develops in the setting of bacteremia (e.g. endocarditis or another endovascular infection)
What is vertebral osteomyelitis?
Develops due to hematogenous spread, local tissue invasion (e.g. from psoas abscess) or direct inoculation after a procedure
What is non-hematogenous osteomyelitis?
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
What are some DDx for osteomyelitis?
Cellulitis Septic arthritis Gout Diabetic or arterial insufficiency ulcer Tuberculous or mycotic bone infection Rheumatic fever Metastatic cancer Multiple myeloma Avascular necrosis
What is the most sensitive imaging modality of osteomyelitis?
MRI
What are the two ways to make a diagnosis of osteomyelitis?
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)
What is sporotrichosis?
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
What is the most common form of sporothrichosis?
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
What is the progression of sx for sporotrichosis?
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
