Acute osteomyelitis Flashcards
Definition
Osteomyelitis=
osteon (bone) +myelo (bone marrow) +itis (inflammation)
= inflammation of the bone, bone marrow, produced by
infection on a hematogenous way (most common)
with a pyogenic germ, cutaneous of predilection, which appears at the level of the metaphyses of the long bones
Classification
Source of the infection
Hematogenous osteomyelitis (the most common route – hematogennous spred from bacteremia – consequance of other infections such as otitis media, pharyngitis, sinusitis)
Contiguous infection (local invasion or direct inoculation from penetrating trauma)
Classification
Based on the time of onset
Acute – symptomatology for less than 2 weeks
Subacute – between 2 and 6 weeks
Chronic - more than 6 weeks (about 17% of acute osteomyelitis becomes chronic)
Etiology
- Staphilococcus aureus and streptococcus: 60-90%
- Gram negative bacillus (Escherichia coli or Haemophilius influenzae)
- Pneumococcus
- Mycobacterium tuberculosis
- Rare: fungal, anaerobi
Etiological particularities:
Age
Comorbidities
Other particular circumstances
Epidemiology
- The prevalence of S. aureus infections has decreased from 55% to 31% in the last 20 years (by increasing personal hygiene)
- Osteomyelitis produced by direct inoculation or contiguity has increased in incidence
- Due to increase of road accidents and osteosynthesis surgeries
- Osteomyelitis has a high incidence in immunocompromised people
- Gender ratio b / f: 2.5 / 1
- Are frequently monomicrobial
Location
AHO most commonly affects the metaphyseal region of long bones:
- Femur (27%)
- Tibie (22%)
- Humerus (12%)
Contiguous osteomyelitis:
- Entrance gate (known/inapparent)
- Folliculitis, infected wounds, erosions, panaritium, prolonged intravenous approaches
- Iatrogenic
Location - theory
Hobo, 1921:
Slow and turbulent blood
Flow in the metaphyseal region = favorite space
for bacterial insemniation
↓
metaphyseal abscess
Pathophysiology
For the joints with the metaphysis located
intraarticularly (shoulder, elbow, hip and ankle), we can
see the extension of the bone infection => septic
arthritis!!!!
Pathophysiology’
0-18 months: neonate the entire epiphysis shares a blood supply with the metaphysis => epiphyseal abscess
> 18 months: after development of the secondary ossification center, the metaphysis and epiphysis have
separate blood supplies
When the growth ends, the communication between
the 2 circulations resumes
Diagnosis
- Clinical examination
- Laboratory findings
- Ultrasound
- Radiography
- MRI
6.Aspiration culture and blood culture- essential for the
etiological diagnosis
Clinical exam
- Fever, dehydration, glassy eyes
- Fatigue, irritability
- Altered general condition
- Limiting mobility
- Local signs (swelling, pain, hyperemia, local temperature rise)
- Pain like a fracture but with normal X-ray
Clinical exam - newborn
Fever may be missing
only 50% have fever
General exam– essential: inspection of position and spontaneous movements Assessment of mobility of all joints Pseudoparalytic attitude Lack of spontaneous movements
A!!! There may be multiple sites of osteomyelitis
Laboratory studies
- Complete blood count (wbc)
- Inflamation markers (CRP – most sensitive and reliable, ESR,Fibrinogen)
- Blood culture
- Procalcitonin
- Cultures from the abscess
- Cultures from the bone tissue (necrosis area)
A! Results may be inconclusive when we have a fistula and we are harvestig purulent material from the skin
Radiology
X-Ray:
unchanged in the firs 10-20 days, initially swelling of the soft tissue
Osteopenia, bone destruction, periosteal reactions, sclerosis (late)
Dd: neoplastic lesions, fractures
(cortical erosion of the distal femoral metaphysis)
Radiology
ultrasonography:
May detect subperiosteal abscess
Evaluates the adjacent joint
