6: Bone and joint infections Flashcards
Infection presents with all the cardinal features of ___, but not all ___ is infectious.
inflammation
What are the cardinal features of inflammation?
Rubor - redness
Calor - hot
Dolor - painful
Tumor - swelling
Loss of function
Generally, when should you start antibiotics?
What are the exceptions?
When you know for sure that it’s an infection - through investigation
If the patient is imminently going to die / lose stuff - sepsis, necrotising fasciitis
How long should suspected bone and joint infection specimens be cultured for?
1 week
otherwise standard 48hrs
What are some inflammatory markers analysed in blood tests?
CRP
PV
ESR
What cells pick up technetium?
Osteoblasts
So scan indicates increased turnover, metabolic activity
What does MRI pick up as opposed to X-ray?
Soft tissue swelling, fluid
Useful for seeing pus-filled abscesses in osteomyelitis
What is osteomyelitis?
Infection of bone
What is the most common means of developing acute osteomyelitis?
Post-trauma / open fractures
By which means may infection get to bone in children and immunosuppressed people?
Haematogenous spread (via blood)
Which bugs are usually responsible for acute osteomyelitis in:
a) adults
b) children?
a) Adults - Staph. aureus
b) Kids - Haemophilus
What must be done to open fractures to reduce the risk of osteomyelitis?
Debridement
What process gives pathogens an opportunity to spread to bone via blood vessels?
Thrombosis
revise virchow’s triad
Which scan is good for picking up osteomyelitis?
MRI scan
If there’s pus in a wound, what should you do?
Drain it
Why don’t antibiotics help when abscesses are involved in osteomyelitis?
Abscess has no blood supply so antibiotic won’t penetrate it
What can the drained pus from an abscess be used for?
Culture
What is sequestrum?
Dead bone
Does sequestrum has a blood supply?
No
Sequestrum should be (removed from / left in) a wound.
removed from
What occurs if acute osteomyelitis isn’t treated?
Chronic osteomyelitis
If chronic osteomyelitis isn’t treated, where can the pus go?
What happens to bone as a result of the pus?
Joint cavities
Underneath periosteum
More bone death
What is an involucrum?
Growth of new bone around sequestrum as seen in osteomyelitis
Which joint infection aggressively destroys joints within 1-2 days?
Septic arthritis
Septic arthritis tends to affect (adults / children).
children
If a joint space reappears on X-ray in a patient with osteoarthritis, what’s happened?
Filled with pus
Patient has septic arthritis
What conditions are associated with septic arthritis?
Sepsis
Septicaemia
Does osteomyelitis lead to septic arthritis?
Can do
and vice versa
What does dark bubbles in soft tissue on a X-ray indicate?
Gas-forming organisms in soft tissue
Patient may have crepitus
Soft tissue infection doesn’t produce any pus early on. What are good “best guess” antibiotics used to treat it?
Flucloxacillin
Benzylpenicillin
Which soft tissue infection, causing severe pain, causes death within days if not treated?
What sign may they have on palpation?
Necrotising fasciitis
Crepitus - gas forming organisms in soft tissue
How is necrotising fasciitis treated?
Removal of all affected tissue
Samples obtained from debridement and pus draining can be used for what?
Biopsy
Culture
In which groups of patients should back pain be taken very seriously?
Red flag patients
Children
Teenagers
What is septic arthritis called if it’s found in the intervertebral discs?
Discitis
What organism tends to cause discitis?
Staph. aureus
Patients with discitis are given ___ and only operated on if they don’t respond. Why?
antibiotics
Spine is really difficult to operate on
What foreign body, found in joints, can become infected?
Joint replacements
What types of Staph. are associated with prosthetic joint infections?
Coagulase negative Staph.
e.g staph epidermidis
What is produced by microbes in joints, making treatment with antibiotics difficult?
Biofilms
slimy stuff
Demarcation of the bone and cement surfaces around prosthetic joints indicates ___ of the joint secondary to what?
loosening of prosthetic joint
Infection
What must be released from infected prosthetic joints?
Pus
How are operating theatres kitted out to reduce rates of infection?
Air control - clean filtered air pumped in via laminar flow diffuser
What other factors affect the rate of infection in operating theatres?
Hand washing (5 mins)
Neat surgery
What is given to the patient as infection prophylaxis before surgery?
Antibiotics
4Cs, flucloxicillin
sa and se most responsible for infections
mrsE treated with tychoplanin
