Orthopaedic Infections Flashcards
What type of bone does osteomyelitis affect?
compact, spongy and bone marrow
What is infection in osteomyelitis usually caused by?
bacteria, occasionally fungal
How can organisms infect bone in osteomyelitis?
trauma, surgery or indirectly by haematogenous spread
In osteomyelitis, what causes osteolysis?
enzymes from leukocytes
What impairs local blood flow in osteomyelitis, making it hard to eradicate?
pus formation
What is the name for a dead fragment of bone which can form in osteomyelitis which usually breaks off?
sequestrium
At what point in osteomyelitis will antibiotics alone not cure the infection?
once an equestrium has formed
What is the name for new bone which will form around the area of necrosis in osteomyelitis?
an involucrum
In the absence of recent surgery, who is acute osteomyelitis likely to occur in?
children or immunocompromised
In children, what to the metaphyses of long bones contain which can result in accumulation of bacteria and infection spreading towards the epiphysis?
abundant tortuous vessels with sluggish flow
In neonates and infants, certain metaphyses are intra articular, including what? What does this mean can happen?
proximal femur, proximal humerus, radial head and ankle
infection can spread into joint causing septic arthritis to also occur
What do infants have which may cause an abscess to extend widely along the subperiosteal space?
loosely applied periosteum
What is Brodie’s abscess?
children develop subacute osteomyelitis with a more insidious onset, where bone reacts by walling off the abcess with a thin rim of sclerotic bone
What does chronic osteomyelitis develop from?
untreated acute osteomyelitis
can be associated with a sequestrum/involucrum
In adults, where does chronic osteomyelitis tend to be?
axial skeleton with haematogenous spread from pulmonary or urinary infections
What may be a cause of peripheral chronic OM?
internal fixation or previous open fracture
What can cause chronic OMG particularly in the spine through haematogenous spread from primary lung infection?
TB
Name the causative organisms for osteomyelitis in newborns (younger than 4 months).
Staph aureus, enterobacter sp, and group A and B strep
Name the causative organisms for osteomyelitis in children (4 months to 4 yrs).
staph aureus, enterobacter sp, group A strep, haemo influenza (reduced with vaccine),
Name the causative organisms for osteomyelitis in children aged 4 to adults?
staph aureus
occasionally enterobacter or streptococcus
Name the causative organisms for osteomyelitis in sickle cell anaemia patients.
Staph aureus most common, also Salmonella (unique to sickle cell patients)
How can osteomyelitis be classed?
superficial (affects outer surface of bone) OR medullary
localized
diffuse (segment of bone is infected leading to skeletal instability)
How is acute osteomyelitis treated?
best guess antibiotics firstly (Fluclox)
unless abscess formation - need surgical drainage
What should be done if acute osteomyelitis fails to resolve after first line of antibiotics?
second line antiBs
or surgery to gain samples for culture
How can chronic osteomyelitis be treated?
NOT by antibiotics alone
ALso need surgery to gain deep bone tissue cultures, to remove sequestrum and excise any infected or non viable bone (DEBRIDEMENT)
What is a problem with debridement?
may result in instability, bone must be stabilized by internal or external fixation
What is the advantage of external fixation?
bone can be subsequently lengthened if it has been shortened as a result of the debridement
What are continued for several weeks after surgery to treat chronic OM?
IV antibs
Who are at particular risk of osteomyelitis of the spine?
poorly controlled diabetics, IV drug users, immunocomp
What is the commonest location where in the spine which OM can present?
lumbar spine
How does a patient present with OM of the spine?
insidious onset of back pain which is constant and unremitting
What are signs of spinal OM?
muscle spasm
spinal tenderness
may have systemic upset
Severe cases of spinal OM may have lower motor neurone/cauda equine syndrome below where and upper motor neurone and myelopathy above where?
L1
What may vertebral collapse lead to in spinal OM?
kyphosis
vertebra plana (flat vertebra)
disc space may reduce
What should also be considered in spinal OM?
endocarditis
What treatment is given for spinal OM?
high dose IV antibiotics after CT guided biopsy to gain tissue culture
may need for several months
May need surgery - debridement, stabilization, fusion of vertebrae
How does septic arthritis present?
severely painful, red, hot swollen and tender joint (similar to gout)
How do pathogens spread to the joint in septic arthritis?
often via the blood or from adjacent tissues
Or from direct penetration e.g. rose thorn, tooth penetration
What is the most common cause of septic arthritis?
staph aureus
In whom is E.coli a cause of septic arthritis?
elderly, immunocomp, IV drug users
Do bacterial infections cause irreversible or reversible damage to hyaline cartilage in joints?
can be irreversible within days
What can metaphyseal osteomyelitis lead to?
septic arthritis
What should be suspected if more than on joint or bone is affected by septic arthritis?
endocarditis
What should be done for any joint suspected of being septic?
aspiration before antibiotics are given
a single dose of antibiotics can lead to a falsely negative gram stain and culture
What is the normal treatment for septic arthritis?
surgical washout
What can act as a very effective culture medium for bacteria to thrive on in soft tissues?
haematoma
How do bacteria normally enter the operative site during surgery?
from patient’s own skin
What is there a risk of when a deep infection complicates a fracture fixation?
chronic osteomyelitis
non union of fracture
Name a bacteria which causes a more low grade infection, most often diagnosed late?
staph epidermis and enterococcus
What is the treatment for orthopaedic infection?
surgery (before antibs)
