Orthopaedic Infections Flashcards
What type of organisms usually cause osteomyelitis?
Mostly bacteria, sometimes fungi
How can organisms get into bone directly?
From penetrating trauma or surgery
How can organisms get into bone indirectly?
Haematogenous spread from infection at a distant site
Which patients are at increased risk of osteomyelitis?
Immunocompromised, chronic disease, elderly and young
What is osteolysis?
An inflammatory response in bone which leads to resorption
Once a bone is infected, enzymes from leukocytes cause local osteolysis which causes what?
Pus to form, which impairs blood flow and makes the infection difficult to eradicate
What is a sequestrum?
A dead segment of bone
Once a sequestrum breaks off in osteomyelitis, how does this alter the treatment?
Antibiotics alone will no longer cure the infection
What is an involucrum?
New bone forming around an area of necrosis
Acute osteomyelitis, in the absence of recent surgery, usually occurs in who?
Children or immunocompromised adults
In children, the sluggish metaphyseal blood flow leads to the accumulation of bacteria and infection spreading towards what part of the bone?
Epiphysis
In neonates and infants, certain metaphyses are intra-articular, what is the significance of this?
Infection of bone can spread into the joint causing co-existant septic arthritis
Infants have a loosely applied periosteum- what is the significance of this?
An abscess can extend widely
What will the onset be of subacute osteomyelitis in children?
Insidious
Subacute osteomyelitis in children may lead to the formation of a Brodie’s abscess- what is this?
The bone reacts to an abscess by walling it off with a thin rim of sclerotic bone
In adults, in which skeleton does chronic osteomyelitis tend to be?
Axial (spine and pelvis)
Chronic osteomyelitis in the axial skeleton of adults usually comes from where?
Haematogenous spread from pulmonary or urinary infections, or discitis
Why does chronic osteomyelitis not present earlier?
It gets suppressed by antibiotics and can lay dormant for many years before reactivating
What are some symptoms that reactivation of chronic osteomyelitis may cause?
Localised pain, inflammation, systemic upset, discharge
What lung infection is known for causing chronic osteomyelitis, especially of the spine?
TB
What is the most common organism causing chronic osteomyelitis?
Staph Aureus
What organism causing osteomyelitis is unique to patients with sickle cell anaemia?
Salmonella
What does it mean if osteomyelitis is classed as ‘diffuse’?
A segment of bone is infected, causing skeletal instability
What is the treatment for acute osteomyelitis?
Best guess antibiotics IV, unless there is an abscess which requires surgical drainage
If an acute osteomyelitis fails to settle after initial treatment, what should be done?
Second line antibiotics or surgery to gain samples/remove infected bone/washout
What are the purposes of surgery fro chronic osteomyelitis?
Gain deep cultures / Remove sequestrum / Debridement
What is the complication of surgical debridement of bone?
Instability
If surgical debridement of a bone results in instability, what needs to be done?
Internal or external fixation
What is the advantage of using external fixation for instability following bone debridement?
The leg can be subsequently lengthened
Which populations are at increased risk of osteomyelitis of the spine?
Poorly controlled diabetics, IV drug users, immunocompromised patients
If osteomyelitis occurs in the spine, which area does it normally affect?
Lumbar
How will patients with osteomyelitis of the spine present?
Insidious onset of back pain which is constant and unremitting
Apart from back pain, what are some other symptoms that people with osteomyelitis of the spine might present with?
Paraspinal muscle spasm, fever, systemic upset
What tests should you do for osteomyelitis of the spine?
MRI and blood cultures
If a patient has osteomyelitis, you should consider which other infection may also be present? How would you test for this?
Endocarditis- ECHO
How is a tissue culture obtained for osteomyelitis of the back?
CT guided biopsy
What is the treatment for osteomyelitis of the spine?
High dose IV antibiotics (possibly for months)
If surgery is required for osteomyelitis of the spine, what can be done?
Debridement, stabilisation and fusion of adjacent vertebrae
What aspect of soft tissue injuries can act as a very effective culture medium for bacteria to thrive on?
Haematoma
What is the concern when a deep infection complicates a prosthetic joint replacement?
Development of chronic infection with pain, poor function sepsis, discharge and loosening
What is the concern when a deep infection complicates a fracture fixation or stabilisation?
Chronic osteomyelitis and non-union of the fracture
What are some common virulent organisms which produce an early prosthetic infection?
Staph aureus, gram - bacilli including coliforms
What are some organisms which may cause a low grade infection of a prosthetic joint and can present up to a year after surgery?
Staph epidermidis, enterococcus
