bone and joint infections Flashcards
-septic arthritis -pott's disease -osteomyelitis -prosthetic bone + joint infection
Define septic arthritis
infectious agent in a joint leading to arthritis
Define osteomyelitis
infection and inflammation of bone marrow
Difference between acute + chronic septic arthritis
acute = PYOGENIC (fever + malaise) chronic= non pyogenic
Most common organism causing septic arthritis
staphylococcus aureus
- gram positive cooci
- 60% all cases
Pathogenesis is septic arthritis
infection in joint
- activates innate immune system - immune cells lead to pro-inflammatory cytokine release - joint destruction
- toxins + enzyme released by the pathogen itself - joint destruction
Most commonly affected joint in septic arthritis
knee joint = 50% cases
Biggest risk factors for septic arthritis in adults
- pre-exisitng arthritis = OA/RA
- trauma (surgery/joint replacement)
Biggest cause for septic arthritis in kids
idiopathic
followed by pre-existing infection
Synovial joint examination results in septic arthritis
SF- purlent (yellow-puss)
- high leukocytes count - gram stain positive (1/3rd cases) - low glucose (respiration for pathogens)
Blood test results in septic arthritis
- raised ESR or CRP (inflammation)
- neutrophilia (esp in kids)
Radiological changes in septic arthritis
-soft tissue swelling
-joint capsule distension
(>2wks before changes seen - joint destruction already occurred)
Differential diagnosis for septic arthritis
- gout
- pseudogout
- OA
- RA
Radiological features for septic arthritis
similar presentation to OA
- narrowing joint space
- bone erosions
- effusion
BUT CYST FORMATION + NO OSTEOPHYTES
Management of septic arthritis
- DRAINAGE - debridement + wash out (lowers bacterial load)
- broad spectrum antibiotics (prior to blood culture)
- blood culture
- gram specific antibiotics
Name some broad spectrum antibiotics
CI-PRO-FLOXA-CIN
PIPER-A-CILLIN
Name an antibiotic which can be given as a foam directly to the joint
(instead of standard oral method for antibiotics)
CLINDA-MYCIN
Name a gram positive antibiotic
FLUCLOXACILIN
Name an antibiotic used specifical in chronic osteomyleitis
vancomycin (with cement beads)
What is the most common route of infection in septic arthritis and osteomyelitis
HAEMTOGENOUS
what type of osteomyelitis is seen more commonly in kids
acute OM
-kids are vulnerable to OM - due to open EGP
What is Pott’s disease
OM of the vertebral bodies caused by infection with tuberclin (TB)
(spinal OM =>45yr olds)
what are the 2 predisposing factors for OM
1.impaired blood flow
diabetes + DVT + radition fibrosis + small risk with SC patients
2.impaired immunity -malnutrition, elderly, neonates + infants (not fully vaccinated + underdeveloped immune system)
In OM, what is the biggest predisposing factor for impaired blood flow
DIABETES MELLITUS (30-40% of OM patients)
clincial features of OM
- abrupt onset of fecer (esp in kids)
- decreased limb movement
- localised
diagnosis of OM
RADIOLOGICAL FINDINGS - lytic center with ring of sclerosis
+blood culture
Complications of OM
- amyloidosis
- SCC
Management of OM
- surgical debridement + wash out (remove dead bone)
- reconstruct bone (using allograft + autograft)
- antibotics (4-6wks- 1st 2 wks IV)
Prosthetic bone and joint infection
- causes
- RF
- prevention
- inoculation at surgery / post op sepsis
- old age/obesity/ RA/corticosteroid therapy
- aseptic operating theatre/pre-op antibiotics
Management options for prosthetic bone + joint infection
- retain/ remove +replace prosthesis - debridement + wash out + antibiotics (then replace
- resection athroplastyr
- L.T supressive antibiotics
