Osteosarcoma and Osteomyelitis Flashcards
What is an osteosarcoma?
A primary osseous malignant neoplasm composed of mesenchymal cells producing osteoid and immature bone, even if only in small amounts.
What is an Ewings sarcoma?
Soft tissue sarcoma in the bone
What are osteosarcoma and Ewing’s sarcoma?
Child/ Adolescent bone tumours
Osteosarcoma is more common than Ewing sarcoma
Who is more likely to have bone tumour?
Males
Ewing sarcoma happens in younger children
What are the clinical features of bone tumours?
• Limbs are the most common site
• Persistent localised bone pain
o Indication for an X-ray
• Most patients are otherwise well
What investigations do you do for bone tumours?
• Plain X-ray
o Shows bone destruction and periosteal new bone formation
o In Ewing sarcoma, there is often a substantial soft tissue mass
• MRI
• Bone scan
• Chest CT (to look for lung metastases)
• Bone marrow sampling (exclude bone marrow involvement)
What is the management for bone tumours?
- Surgery with adjuvant or neo-adjuvant chemotherapy
- Amputation is avoided if possible
- Radiotherapy may be used for local disease or where resection is impossible
What is osteomyelitis?
Infection of the METAPHYSIS of the
long bones, usually due to
haematogenous spread of the pathogen
What causes osteomyelitis?
Due to biofilm-forming bacteria
A biofilm is a highly structured community of bacterial cells that adhere to an inert or living
surface
What are common sites for osteomyelitis?
o Distal femur
o Proximal tibia
How does osteomyelitis progress onto septic arthritis?
Where the joint capsule is inserted distal to the epiphyseal plate (e.g. as in the hip), osteomyelitis may spread to cause septic arthritis
What pathogens can cause osteomyelitis?
o Staphylococcus aureus: most common o Streptococcus ▪ Group B Strep in neonates ▪ Beta haemolytic Strep o Haemophilus influenzae o In sickle cell anaemia, there is increased risk of staphylococcal and salmonella osteomyelitis o Tuberculosis: rare but consider in immunodeficient child
What are the clinical features of osteomyelitis?
• Markedly painful, immobile limb (pseudoparesis)
• Acute febrile illness
• Swelling of skin and exquisite tenderness over the infected site
• Movement of limb causes severe pain
• May be a sterile effusion of an adjacent joint
• Back pain (vertebral infection)
• Limp or groin pain (pelvis infection)
• Occasionally there may be multiple foci e.g. disseminated staphylococcal or H influenzae
infection)
What investigations do you do for osteomyelitis?
• Blood cultures (usually positive)
o Take BEFORE starting antibiotics
• WCC and CRP are raised
• X-rays are initially normal
o After 7-10 days, subperiosteal new bone formation and localised bone
rarefaction become visible
• Ultrasound may show periosteal elevation at presentation
• MRI allows identification of infection in the bone (subperiosteal pus and purulent debris in
the bone)
• Radionuclide bone scan may be helpful if the site of infection is unclear
What is the management of acute osteomyelitis?
o High-dose IV empirical antibiotics (usually for 2-4 weeks)
o Once the patient has demonstrated clinical recovery and acute-phase reactants have
returned to normal, patients can be switched to oral antibiotics
o The regimen should be altered once results of MC&S arrive
o NOTE: in children who respond well, early transition to oral antibiotics (after 3 days
to 1 week) may be considered
o Affected limbs should be immobilised, analgesia should be given and associated
comorbidities should be addressed
o Surgical debridement may be necessary if there is dead bone or a biofilm
