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
Radiology
MRI examination:
The most sensitive imaging exploration
- 97% sensitivity
- 94% specificity
Useful in the early stages
Unavailable in case of emergency
Sedation is required in younger children
Treatment
- Aspirative serial punctures (articular, subperiosteal, metaphyseal)
- surgery “ubi pus ibi evacua”
- Presence of abscess (pus evacuated when puncture) –surgical emergency
- Radiological evidence of necrosis
- Lack of antibiotic response
- Antibiotic therapy
- Cast immobilization
Surgical treatment
- Aspirative serial punctures : articular -> subperiostic -> metaphyseal
- No abscess (white puncture)
- Conservative treatment + antibiotherapy
- Surgical treatment in case of developing an abscess in evolution
- With abscess (puss in any of the 3 punctures)
- Surgical treatment instituted in emergency
Surgical treatment ‘
- Open irrigation and drainage of pus, hematoma and granulation tissue
- Cortical drilling or fenestration
- Curettage of the medullary canal (with care to avoid growth plate)
- Open of the joint, irrigation and drainage of the joint in case of septic arthritis
Antibiotic therapy
- Initially empirical
- Avoids sepsis and bone destruction
3.Later adjusted according to the results of culture and
sensitivity results
4.Often the culture is negative even if there is local pus (A!Unwise use of antibiotics)
Antibiotic therapy’
Administration
- intravenous
- Oral in the 3rd week if the evolution is favorable
Monitoring the response to treatment
- Unfavorable evolution: clinically, CRP does not decrease,worsening of MRI lesions => re-evaluation of the treatment
Continues for 4-6 weeks
Complications
- Sepsis
- Chronic osteomyelitis (up to 17%)
3.Growth arrest, limb length discrepancy, axial
deviation
- Pathological bone fractures
- Irreversible functional changes
