Osteomyelitis - TM

Question 1

What is it?

Answer 1

Infection of bone
Either acute or chronic

Question 2

How can it be caused?

Answer 2

3 routes of spread:
* Haematogenous
* Direct inoculation (eg following open #)
* Direct spread from nearby infection (eg adjacent septic arthritis)

Question 3

Most common causative organisms

Answer 3

• Staphylococcus aureus
• Streptococi
• H.influenzae
• P.aeruginosa (esp IV drug users)
• Salmonella - in people with sickle cell disease

Question 4

Pathophys of osteomyelitis

Answer 4

• Bacteria enter bone tissue
• Express adhesins to latch onto host tissue and proteins
• Pathogens then propagate, spread and seed further into the tissue

Question 5

What can happen in chronic osteomyelitis?

Answer 5

• 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

Question 6

What is an involucrum?

Answer 6

• Following sequestrum formation
• Region becomes encased in thick sheath of new periosteal bone

Question 7

RF OM

Answer 7

• Diabetes mellitus
• Immunosupression
• Alcohol excess
• IV drug user

Question 8

OM and diabetic foot case

Answer 8

• 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

Question 9

Clinical features of OM

Answer 9

• 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

Question 10

What is Potts disease?

Answer 10

• 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

Question 11

Potts disease investigation and management

Answer 11

• MRI spine
• Most cases need prolonged anti-TB medication
• Sometimes surgery is needed for abscess drainage

Question 12

Investigations for OM

Answer 12

• 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

Question 13

Findings on x-ray for OM

Answer 13

• 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)

Question 14

Management OM - medical

Answer 14

• 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

Question 15

Management OM - surgery

Answer 15

• 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

Question 16

Complications of OM

Answer 16

• Sepsis
• Septic arthiritis
• Soft tissue infection
• Children - growth disturbances, premature physeal growth closure
• Chronic infection

Question 17

Chronic OM presentation

Answer 17

• Localised ongoing pain
• Draining sinus tract
• Can have NORMAL inflam markers and NEGATIVE blood cultures

Question 18

Management of chronic OM

Answer 18

• Surgical local bone and soft tissue debridement
• Extensive long term abx therapy
• –> complex reconstruction and prolonged rehab