Bone and Joint Infections Flashcards
What are some investigations that can be done for bone and joint infections?
Useful blood tests = CRP, PV
Occasionally useful blood tests = blood cultures, white cell count, ESR
X-rays, technetium scan, MRI
When does acute osteomyelitis mostly occur?
Post-trauma or post-operative (inoculation of infectious agent)
How does acute osteomyelitis spread in children and the immunosuppressed?
Haematogenous spread
What are some causative organisms of acute osteomyelitis?
Most common = Staph aureus
Haemophilus influenza in children
Also pseudomonas and enterobacteriaceace
What are risk factors for acute osteomyelitis?
Smoking, diabetes (especially diabetic foot ulcers), kidney failure
What are the symptoms of acute osteomyelitis?
Fever, swelling and warmth of affected joint, pain, fatigue
How is acute osteomyelitis treated?
Surgery and drainage of pus may be needed, treated with antibiotics for 4-6 weeks
How is chronic osteomyelitis diagnosed?
Blood tests often unhelpful, use plain x-rays and MRI
Gold standard diagnosis = positive bone cultures and histopathologic examination of bone
What may occur in chronic osteomyelitis?
Bone sequestration and destruction
Involucrum = growth of new bone around dead bone
What is the most common causative organism in chronic osteomyelitis?
Staph aureus
How is chronic osteomyelitis treated?
By removing all pathogens and devitalised tissue, usually by surgical debridement
How can septic arthritis be spread?
From inoculation, metaphyseal spread or direct haematogenous spread
What are the symptoms of septic arthritis?
Swelling, redness and heat in joints that develop quickly over a few hours or days, most common in hips and knees
What are some risk factors for septic arthritis?
Diabetes, IV drug users, joint prostheses, underlying joint disease
What are the causative organisms of septic arthritis?
Most commonly staph aureus and haemophilus influenzae
E.coli and pseudomonas in IV drug users and elderly
What are the investigations and treatment for septic arthritis?
Investigations = blood tests, synovial fluid sample, maybe MRI Treatment = treated with antibiotics for 4-6 weeks and drainage of fluid (arthrocentesis)
What are some examples of soft tissue infections?
Cellulitis and necrotising fasciitis
How should cellulitis treated?
Use best guess antibiotics to cover staph and strep, often flucloxacillin and benzylpenicillin
What are some predisposing events of necrotising fasciitis?
Surgical wounds, puncture wounds form IV drugs, insect bites
What are the general treatments for soft tissue infections?
Debridement following biopsy, let out any pus, antibiotics may be prescribed at low maintenance dose after infection has cleared
What is infected arthroplasty?
Deep infection of prosthetics, usually joint replacements
Symptoms = increased pain and stiffness of joint, swelling, fatigue, fever
What are important questions to ask in a patient with a suspected infected arthroplasty?
Was there ever a wound problem?
Has the wound ever been pain free?
What are some risk factors for an infected arthroplasty?
Immune deficiency or immunosuppression, diabetes, peripheral vascular disease, obesity
What investigations can be done for infected arthroplasty?
CRP, joint aspiration, bone scan (technetium 99), x-ray
How should an infected arthroplasty be treated?
Debridement, single staged surgery (less popular) or staged surgery (usually two staged, needs 6 weeks of follow up IV antibiotics)
What are some elements of surgery controlled to ensure the environment is as sterile as possible?
Easily measured = clean air theatres, local and systemic antibiotics, duration of surgery
Difficult to measure = neat surgery, quality of hand washing, theatre discipline
What are some ways to deliver prophylaxis?
Laminar flow, 24hrs antibiotics starting with induction, antibiotics in cement
What are some antibiotics given for prophylaxis?
Co-amoxiclav, flucloxacillin + gentamicin, clindamycin, co-trimoxazole
What are some common pathogens that prophylaxis is used to protect against?
Staph aureus, staph epidermidis (coagulase negative staph)
What is the aim for infections occurring following joint replacement surgery?
Deep infection of the average joint infection should occur in less than 1% of cases
What is the prognosis like for children with acute bone and joint diseases?
Generally have good outcomes
