Rheumatology Flashcards
Osteomyelitis
inflammatory condition of bone caused by an infecting organism, most commonly Staphylococcus aureus.
When to suscept acute osteomyelitis
Most commonly in an unwell child with a limp, or in an immunocompromised patient.
When to suscept chronic osteomyelitis
most commonly in adults with a history of open fracture, previous orthopaedic surgery, or a discharging sinus
Osteomyelitis- signs- acute
Systemic- Fever, rigors, sweats, malaise
Local- tenderness, warmth, erythema, and swelling
Osteomyelitis- signs- chronic
Systemic- Fever, rigors, sweats, malaise
Local- tenderness, warmth, erythema, and swelling
draining sinus tract
deep / large ulcers that fail to heal despite several weeks treatment (DM ulcer)
non-healing fractures
Native vertebral osteomyelitis- signs
Local back pain associated with systemic symptoms, paravertebral muscle tenderness and spasm
Osteomyelitis RFs
previous osteomyelitis
penetrating injury
intravenous drug misuse
diabetes
Osteomyelitis- investigations
FBC- may be raised WBC (chronic is normal)
ESR/ CRP- usually raised
Blood culture- to identify suitable antibiotic
Plain x-ray of affected area
MRI/ CT
Osteomyelitis- investigations- plain x ray
Chronic- cortical erosion,
periosteal reaction,
mixed lucency,
Sclerosis
sequestra
soft tissue swelling
Osteomyelitis- investigations- MRI
marrow oedema from 3-5 days
Delineates cortical, bone marrow and soft tissue inflammation
Osteomyelitis- investigations- definitive diagnosis
Bone biopsy- 2 samples
Positive blood cultures (50% of acute OM)
Osteomyelitis- differential diagnosis
Soft tissue infection (Cellulitis and erysipelas)
Charcot joint
Avascular necrosis of bone (Causes: steroid, radiation, or bisphosphonate use)
Gout (uric acid crystals in joint fluid / more acute presentation)
Fracture
Bursitis
Malignancy
Osteomyelitis- treatment
Surgical- Debridement or Hardware placement or removal
Antimicrobial therapy
Osteomyelitis- treatment- antimicrobial therapy
Initial broad spectrum empiric therapy
Tailored to culture and sensitivity findings
Bone penetration of drug
Prolonged duration (6 weeks<)
Routes of Osteomyelitis
- Direct inoculation of infection into the bone
trauma or surgery,
poly/ monomicrobial - Contiguous spread of infection to bone
- Haematogenous seeding- children (long bones)>adults (vertebrae), monomicrobial
Routes of Osteomyelitis- Contiguous spread of infection to bone
-from adjacent soft tissues and joints, polymicrobial or monomicrobial,
-older adults: DM, chronic ulcers, vascular disease, arthroplasties / prosthetic material
Osteomyelitis- typical microbe causes
Staphylococcus aureus,
coagulase-negative staphylococci,
aerobic gram-negative bacilli
Osteomyelitis- histopathology- acute changes
Inflammatory cells
Oedema
Vascular congestion
Small vessel thrombosis
Osteomyelitis- histopathology- chronic changes
neutrophil exudates
lymphocytes & histiocytes
Necrotic bone ‘sequestra’
new bone formation ‘involucrum’
Pathogenesis of OM – Host factors
Behavioural factors- risk of factors
Vascular supply- arterial disease, DM, sickle cell disease
Pre-existing bone/ joint problem
Immune deficiency
Periprosthetic joint infection
Infectious complication following total joint arthroplasty (TJA)
Periprosthetic joint infection- common causes of infection
Gram‐positive bacterium is still the most common pathogenic bacteria in PJI
Staphylococcus epidermidis and Staphylococcus aureus were the largest in number.
Periprosthetic joint infection- upper vs lower limb
Propionibacteria more sig problems in upper limb
Periprosthetic joint infection- upper limb and propionibacteria
They are colonisers of humans from the above the waist
Can even be shed by blinking the eyes
Therefore may represent more of a threat in upper limb prostheses and Spines