(3) Septic Arthritis, Chronic Osteomyelitis, TB Flashcards
What is septic arthritis?
non-spinal joint infection
How is septic arthritis commonly spread?
hematogenous or direct implantation
What is the most common infectious organism of septic arthritis?
staph aureus
What are the clinical features of septic arthritis?
- chills
- fever
- edema
- pain
- limping
- erythema
- ^ESR
- ^WBC (left shift)
What are the imaging features of septic arthritis?
- joint effusion distorts fat folds (fat pad signs)
- rapid loss of jt space
- loss of subchondral white line
- aggressive bone destruction
- Late: bony/fibrous ankylosis
What is the most reliable radiographic finding for septic arthritis?
loss of subchondral white line
What are the common locations of septic arthritis?
- MC: knee & hip
- MCPs (fight bite)
What is the most common infectious organism to cause septic arthritis in an IV drug user?
staph aureus
What is the 2nd most common infectious organism to cause septic arthritis in an IV drug user?
pseudomonas
Which organism is known to cause septic arthritis at an increased frequency in IV drug users than other populations?
pseudomonas
What is the term for septic arthritis caused by pseudomonas in an IV drug user?
mainliner syndrome
What are the preferential locations of septic arthritis is IV drug users caused by pseudomonas?
“S” joints:
- spine
- SI
- symphysis
- SC
- (S)acromioclavicular
What is chronic osteomyelitis?
unresolved osteomyelitis (suppurative form of bone/marrow infection)
What are the radiographic findings of chronic osteomyelitis?
- sclerosis
- solid wavy periosteal bone formation
- cortical thickening
- can be superimposed osteolysis
If chronic osteomyelitis undergoes malignant degeneration, what might it become?
- fibrosarcoma
- squamous cell carcinoma
What is the term for squamous cell carcinoma occurring along a draining sinus tract of chronic osteomyelitis?
Marjolin ulcer
Chronic inflammation of the dermis due to a draining sinus tract of chronic osteomyelitis can cause ____
skin ulcers
(if this becomes squamous cell carc = Marjolin ulcer)
What condition can predispose someone to skin ulcers and infections, osteomyelitis, and neuropathic arthropathy?
diabetes
(i.e., foot ulcers that go unnoticed)
What is gas gangrene?
bacterial infection (clostridium) manifesting as gas formation within the soft tissue
Tuberculosis (TB) and syphilis are ____ infections
non-suppurative
What populations are primarily affected by TB?
immunocompromised
What is the infectious organism of TB?
Mycobacterium tuberculosis
Describe the primary stage of TB.
- infects lungs
- acts like simple pneumonia
- leads to granulomatous reaction
- may stay clinically silent for life
Describe the secondary (post-primary) stage of TB.
- reactivation of organism (when immunocompromised)
- spreads to other organs & bone via blood
What age group is primarily affected by skeletal TB?
2-30yrs
(Rare in 1st yr of life)
What are the symptoms of skeletal TB?
- insidious/slow onset
- pain
- decreased ROM
- focal tenderness
What are the 2 most common skeletal locations of TB?
- spine (50%)
- hips (30%)
TB in the spine was formerly known as ____
Pott disease
TB in the spine is called ____
TB spondylodiscitis
What part of the spine is TB more common in?
Thoracolumbar spine
How do the symptoms of TB spondylodiscitis compare to suppurative spondylodiscitis?
Much lower grade
____ can result when the spine collapses due to TB spondylodiscitis.
Pott paraplegia
What are the early imaging findings of TB spondylodiscitis?
- disc space loss (slower than suppurative)
- ant. vertebral body destruction
- subligamentous spread
- propensity to skip levels
What are the late imaging findings of TB spondylodiscitis?
- patho. vertebral collapse
- angular kyphosis (Gibbous deformity)
- calcified abscesses (retropharyngeal, paravertebral, psoas)
What is the term for the radiographic sign of a calcified psoas abscess?
Snowflake sign
(TB spondylodiscitis)
What is Phemister’s triad of TB arthritis?
- progressive & slow jt space narrowing
- juxta-articular osteoporosis
- peripheral/marginal erosions of articular surfaces
(Affecting 1 jt, vs. RA)
What is the term for TB in the finger creating fusiform swelling?
Spina ventosa
(TB dactylitis = fusiform swelling)
What is the term for TB of the frontal bone with scalp abscesses?
Pott puffy tumor
What is the term for subgluteal infective bursitis with direct extension of TB to the ischial tuberosity?
Weaver bottom
What is the likely diagnosis? Give 4 radiographic findings.
Dx: Chronic osteomyelitis
- atrophy
- sclerosis
- cortical thickening
- wavy periosteum
Give 2 differential diagnoses.
- Chronic osteomyelitis
- Paget sarcoma
What radiographic finding helps narrow your differentials?
Positive Waldenstrom sign = Intracapsular effusion in kids
(Dx: septic arthritis)
What is the diagnosis?
Septic arthritis
What is the most likely diagnosis?
Septic arthritis
What is the likely diagnosis? What condition could have caused this?
Dx: septic arthritis
Diabetes
What is the diagnosis? What radiographic sign supports your diagnosis?
Dx: TB spondylodiscitis
Snowflake sign
What is the likely diagnosis?
Septic arthritis
What findings are present?
- Loss of disc space
- loss of subchondral white line
(Dx: spondylodiscitis)
What finding is present?
paraspinal edema
What is the diagnosis?
Chronic osteomyelitis
