Bone & Joint Infections Flashcards
Define Osteomyelitis
Infection of bones
Define Septic arthritis
Infection of joints
What is the biggest causes of bone infections?
What are the other causes of bone infections?
(Bacterial)
Staphylococcus aureus
Steptococci (Beta-haemolytic & Strep. Pneumonaie)
Enteric Bacteria (E.Coli, Salmonella species)
Coagulase Negative Staphlococci (Staph. Epidermidis)
Myobacterium Tuberculosis
What is sequestrum?
Infected bone becomes necrotic
Infected bone becomes necrotic- what is this called?
Sequestrum
What is biofilm? Where do they occur?
Bacteria in an organic matrix on an inert surface. Can form on prosthetic joints
What is involucrum?
New bone formation outside sequestrum
What is Cloacae?
Pus from sequestrum escapes through involucrum via holes
What is discharging sinuses?
Infection & pus from cloacae causes skin necrosis
What are the risk factors for a bone & joint infection?
Direct innoculation (Trauma, Medical procedure, Skin Ulcer)
Contigous Spread (eg: nearby SSTI)
Haematogenous Dissemination (IV drug abuse or IV device)
Immunosuppresion (DM, Renal failure, Sickle cell disease)
What are the Microbial Pathology Factors?
Access
Adherance
Invasion
Multiplication
Evasion
Resistance
Damage
Transmission
What is the pathology- Host Response for Osteomyolitis?
Initial abscess starts in cortex progresses into subperiosteal space
Sequestrum
Involucrum
What would you expect to see as a host response in chronic osteomyelitis?
New brittle bone
Pus
Decreased medullary cavity
Dying bone marrow
What are the general clincal features of inflammation?
Pain
Loss of function
Erythema
Warmth
Swelling
What is the presentation of osteomyelitis?
Pain, Swelling, Loss of function, Erythma, Warmth
Fever, pathological fractures, discharging sinuses
What are common forms of osteomyelitis?
(think more causes)
Traumatic infection, Operative infections, Predisposing factors (eg: DM foot), Infected Haematoma, Pressure sores etc..
What are the Inx you would conduct?
(5 key groups)
Bloods:
- FBC & CRP
- Blood tests to look for sepsis- eg: Lactate
- Blood cultures
Skin samples:
- Swabs
Imaging:
- X-Ray: Late changes not early changes visible (periosteal reaction = earliest visible sign)
- CT scans: Show bone changes
- MRI: Good for soft tissue changes
Joints Aspiration:
- MC&S (may show bacteria, crystals, WBCs)
- Synovial fluids may be: Non viscous, Turbid, Purulent, Blood stained
Bone Bx:
- Sample for culture, PCR test & Histopathology
What is the treatment?
- Manage sepsis
- Empirical Abx = IV Fluclox & IV Benpen
- (2-6 weeks IV then 4-6 weeks PO)
- Take samples before Abx if possible
What should you do if there is septic arthritis
Joint washout
When might surgery for osteomyelitis be needed?
If chronic changes have occured
How would you deal with a prosthetic joint infection?
Removal & replace with abx continues in between ops
How can you prevent Bone & Joint infections?
Promt Dx & Tx of predisposing conditions
Aspectic conditions for joint replacements
Antibiotic embedded into cement for prosthetic joints
What is the clinical features of spetic arthritis?
Pain, Loss of function, Erythema, Swelling, Warmth
Fever, Damage to Articular Surface (tends to be more acute presentation as in an enclose space)
