MSK: Osteomyelitis Flashcards
What is osteomyelitis?
Infection of the metaphysis of long bones
Where are the most common sites?
Distal femur
Proximal tibia
How is it spread?
Haematogenous, but may arise by direct spread from infected wound
Is the skin swollen directly over the infected site?
Yes
When might osteomyelitis spread to cause septic arthritis?
When the joint capsule is inserted distal to the epiphyseal plate, as in the hip
What are most infections caused by?
Staphylococcus aureus
Other pathogens include streptococcus and haemophilius influenza if not immunised
In sickle cell anaemia there is an increased risk of staphylococcal and salmonella osteomyelitis
From TB - especially in immunodeficient child
How does it present?
Markedly painful, immobile limb (pseudoparalysis)
May not have local signs, especially when flat bone affected (older children tend to localise pain)
Directly over site: swelling, tender, erythema
Refusal to weight bear, limping
What does moving the limb cause?
Severe pain
In adjacent joints there may be..
A sterile effusion
Who may presentation be more insidious in?
In infants
How may infection of pelvis present?
Limp or groin pain
What investigations are needed?
FBC, CRP
Blood cultures
What will x ray show?
Initially normal other than soft tissue swelling
Takes 7-10 days for subperiosteal new bone formation and localised bone rarefaction to become visible
What may USS show at presentation?
Periosteal elevation
What does MRI show?
Subperiosteal pus and purulent debris in the bone
How is it managed?
IV antibiotics until clinical recovery and acute phase reactants returned to normal
Oral therapy for several weeks
Surgical drainage if no rapid response to antibiotics
Affected limb rested in a split and immobilised
