Osteomyelitis - TM Flashcards
1
Q
What is it?
A
Infection of bone
Either acute or chronic
2
Q
How can it be caused?
A
3 routes of spread:
* Haematogenous
* Direct inoculation (eg following open #)
* Direct spread from nearby infection (eg adjacent septic arthritis)
3
Q
Most common causative organisms
A
- Staphylococcus aureus
- Streptococi
- H.influenzae
- P.aeruginosa (esp IV drug users)
- Salmonella - in people with sickle cell disease
4
Q
Pathophys of osteomyelitis
A
- Bacteria enter bone tissue
- Express adhesins to latch onto host tissue and proteins
- Pathogens then propagate, spread and seed further into the tissue
5
Q
What can happen in chronic osteomyelitis?
A
- Infection –> devasculariasation of bone
- = necrosis
- = resorption of surrounding bone
- Can cause floating piece of dead bone called a sequestrum - acts as a reservoir for infection
6
Q
What is an involucrum?
A
- Following sequestrum formation
- Region becomes encased in thick sheath of new periosteal bone
7
Q
RF OM
A
- Diabetes mellitus
- Immunosupression
- Alcohol excess
- IV drug user
8
Q
OM and diabetic foot case
A
- Infections occur commonly in diabetic patients on the feet
- Often due to minor trauma
- But due to poor blood flow and neuropathy infections develop quickly and go untreated
- = increased risk of OM
9
Q
Clinical features of OM
A
- Severe pain in affected region
- Low grade pyrexia
- Tender, swollen, erythematous
- Sometimes unable to weight bear
If chronic some patients have no systemic symptoms
If in proximal bones, may just be painful
10
Q
What is Potts disease?
A
- Infection of vertebral body and intervertebral disc by Mycobacterium tuberculosis
- Present with lower back pain +/- neuro features, low grade fever
- Start in disc and then spread to regions around
- Typically thoraco-lumbar
11
Q
Potts disease investigation and management
A
- MRI spine
- Most cases need prolonged anti-TB medication
- Sometimes surgery is needed for abscess drainage
12
Q
Investigations for OM
A
- FBC, CRP
- Blood cultures
- Plain radiographs - but poor accuracy
- MRI scan
- Nuclear medicine scans
- Gold standard - culture via bone biopsy at debridement - but not always needed if clear signs on imaging and +ve cultures
13
Q
Findings on x-ray for OM
A
- Osteopaenia (see through)
- Periosteal thickening (whiter brighter outside of bone)
- Endosteal scalloping (loss inner lining bone)
- Focal cortical bone loss
- New bone apposition (thickening diameter of bone)
14
Q
Management OM - medical
A
- Longer antibiotic therapy - eg longer than 4 weeks (usually 6)
- Tailored to cultures or BNF recommends flucloxacillin +/- fusidic acid or rifampicin for first 2 weeks
- If MRSA - vancomycin/teicoplanin
- Usually via paraenteral PICC line
15
Q
Management OM - surgery
A
- Needed if patient clinically deteriorates or if progressive bone destruction
- Need surgical debridement
- If necrotising soft tissue or systemtic need urgent surgucal debridement
- Leave soft tissue envelope over site to allow healing
- If hardware involve - need specialist input
