Bone and Joint Infections Flashcards
5 cardinal features of inflammation?
Rubor (redness) Calor (heat) Dolor (pain) Tumor (swelling) Functio laesa (loss of function)
Specimens for diagnosis in bone and joint infection?
If indicated, blood culture, joint aspirate, wound swab, etc
Blood tests for bone and joint infection?
- CRP, PV (non-specific marker of inflammation
- WCC
- ESR
Imaging for bone and joint infections?
X-rays can show, e.g: bone abscesses
Technetium (bone) scan - osteoblast reaction at infected sites lights up but this is non-specific
MRI (can show assoc. soft tissue issues)
5 types of bone and joint infections?
- Acute osteomyelitis
- Chronic osteomyelitis
- Septic arthritis
- Soft tissue infections
- Infected arthroplasty
Situations where acute osteomyelitis can occur?
Mostly occurs post-trauma/with open fractures (esp. if an inadequate operation is done)
Children or immunosuppressed individuals (haematogeneous spread)
Pathogens in acute osteomyelitis?
Staph. aureus (most common)
In children, consider Haemophilus
However, any bacterium can cause this
Treatment of acute osteomyelitis?
Once diagnosed, antibiotics and, if there is pus, drainage
Describe chronic osteomyelitis
Pus spreads into the bone’s blood vessels, impairing their flow, and areas of devitalized infected bone form
New bone forms around the necrotic area (called involucrum)
Diagnosis of chronic osteomyelitis?
Blood tests are not very useful
Plain X-rays (can show bone abscesses as an area of lucency with sclerosis around it) and MRI
Treatment of chronic osteomyelitis?
Not every patient requires surgery, as bacteria can become dormant for decades at a time
Open surgery is generally used, whereby the involucrum is opened
Mechanisms by which septic arthritis occurs?
- From inoculation
- From metaphyseal spread
- Direct haematogeneous spread
Importance of septic arthritis diagnosis?
Emergency, as pus can destroy cartilage and the joint
Treatment of septic arthritis?
Drain pus + antibiotics
If the joint is prosthetic, it can be removed and replaced at a later date
Types of soft tissue infections?
Cellulitis (use antibiotics that cover Staph. and Strep. like Flucloxacillin and Benzylpenicillin)
Necrotising fasciitis
Presentation of necrotising fasciitis?
Tend to present with septic shock and are disproportionately unwell; if a hand is pressed on the skin, it feels like bubble wrap underneath
Risk factors for necrotising fasciitis?
Immunosuppression
Cancer
Injury, e.g: with exposure to soil
Treatment of necrotising fasciitis?
Identify the pathogen (biopsy and debridement tend to occur together)
Surgical removal of dead tissue or foreign body
Drainage of pus
Target antibiotics (do not wait to ID the pathogen)
Describe infected arthroplasty
Infected prosthetic joint (a type of DEEP infection); this is a problem that can never be completely cured
Often caused by Staph. epidermidis (produces slime/biofilms)
Hx questions with infected arthroplasty?
Was there ever a wound problem?
Has it ever been pain free? (if not, this is a worrying sign)
Ix for infected arthroplasty?
CRP
Joint aspiration
Bone technetium scan
X-ray
Describe sinuses in infected arthroplasty
A sinus tract can communicate with the infected arthroplast (producing a line between cement and bone on Ix and also filling with dye)
Treatment of infected arthroplasty?
Drainage of pus
Prophylaxis of infected arthroplasty?
Systemic antibiotics for 24 hours starting with induction, usually co-amoxiclav, and local antibiotics (e.g: in cement)
Clean air theatre and controlled duration of surgery
