Acute hematogenous osteomyelitis is the most common type of bone infection seen in children. It typically involves the metaphysis of long bones. Staphylococcus aureus is the most common causative organism. Symptoms include fever and local swelling and tenderness. Diagnosis involves blood tests, imaging like x-rays and MRI, and abscess aspiration if present. Treatment consists of IV antibiotics with surgical drainage if abscess is identified, along with supportive care and monitoring for complications like pathological fractures or chronic osteomyelitis.

1. ACUTE OSTEOMYELITIS

2. Osteomyelitis
Osteomyelitis is defined as an inflammation of the bone
caused by an infecting organism
Mostly bacterial, can be fungal

3. Osteomyelitis
The infection may be limited to a single portion of the
bone or may involve the marrow, cortex, periosteum,
and the surrounding soft tissue
The infection generally is due to a single organism, but
polymicrobial infections can occur, especially in
diabetic foot

4. CLASSIFICATION
Duration of symptoms
Acute < 2 weeks
Subacute 2-3 weeks
Chronic > 3 weeks
 Mechanism of infection
exogenous or hematogenous
Based on the host response to the disease
pyogenic or nonpyogenic

5. ACUTE HEMATOGENOUS
OSTEOMYELITIS
Acute hematogenous osteomyelitis is the most
common type of bone infection and is usually is seen in
children
Staph aureus is the common organism

6. The causes of bacteremia
Localized trauma
Chronic illness
Malnutrition
Inadequate immune system
In many cases, the exact cause of the disease cannot
be identified

7. Pathology
In children, the infection generally involves the
metaphyses of rapidly growing long bones

8. Why metaphysis is infected?
Vascular loops present in the long bone metaphysis
that take sharp bends and empty into venous lakes,
create areas of turbulence where bacteria accumulate
and could cause infection

9. Why metaphysis is infected?
Relative absence of macrophages in metaphyseal bone
Gaps in the endothelium of growing metaphyseal
vessels allow passage of bacteria that may adhere to
type I collagen in the hypertrophic zone of the physis
S.aureus surface antigens may play a key role in this
local adherence
Micro haematoma due to trauma is common in
metaphysis

10. Pathology
Bacterial seeding
Inflammatory reaction, which can cause local ischemic
necrosis of bone and subsequent abscess formation
Intramedullary pressure increases
Purulent material escape through the cortex into the
subperiosteal space
Subperiosteal abscess then develops
Periosteum is lifted away from bone
Ischaemia of bone
Extensive sequestra formation and chronic osteomyelitis

11. Pathology

12. Pathology
The age distribution of acute hematogenous
osteomyelitis in children is bimodal
Children younger than 2 years
Children 8 to 12 years old
In children younger than 2 years, some blood
vessels cross the physis and may allow the spread of
infection into the epiphysis

13. Pathology
In children older than 2 years, the physis effectively acts
as a barrier to the spread of a metaphyseal abscess
Because the metaphyseal cortex in older children is
thicker, the diaphysis is at greater risk in these patients
If the infection spreads into the diaphysis, the endosteal
blood supply may be jeopardized
With a concurrent subperiosteal abscess, the periosteal
blood supply is damaged and can result in extensive
sequestration and chronic osteomyelitis if not properly
treated

14. Causative Organisms
S. aureus
Group B streptococcus
Gram negative coliforms
Haemophilus influenzae infections occur
primarily in children 6 months to 4 years old

15. Symptoms
General – fever, sweating, chills and rigors, patient
is usually in shock
Local – local swelling, limitation of movement

16. Signs
General – increased temperature, increased
pulse rate, signs of dehydration and shock
Local – tenderness, local erythema, raised
temperature, decreased movements, fluctuation
(20%) and effusion (10%) may be present

17. Diagnosis
Evaluation of Acute Hematogenous Osteomyelitis
 History and physical examination
Laboratory tests:
 White blood cell count
 Erythrocyte sedimentation rate
 C-reactive protein
 Plain radiograph
 Technetium-99m bone scan
 MRI
 Aspiration for suspected abscess

18. X-rays
< 48 hours
Few changes
Rarefaction is the earliest sign
Loss of demarcation of line between subcutaneous
shadows and muscles
Appearance of transverse lines of increased densities
outward from the muscles
>2 weeks
Periosteal new bone formation is seen
Rarefaction

19. 
Osteomyelitis of the tibia in a
young child. Numerous
abscesses in the bone show
as radiolucency.

20. General supportive care
Intravenous fluids
Appropriate analgesics
Comfortable positioning of the affected limb
Frequent serial examinations should be done

21. Treatment
Empirical antibiotic coverage for the most likely
infecting organism should be started if Gram
stain is negative, and the patient should be
carefully monitored
The C-reactive protein should be checked every
2 to 3 days after the initiation of antibiotic
therapy
If no appreciable clinical response to antibiotic
treatment is noted within 24 to 48 hours, occult
abscesses must be sought, and surgical drainage
should be considered

22. Treatment
If an abscess requiring surgical drainage is found by
subperiosteal or bone marrow aspirate, surgical
drainage and intravenous antibiotics based on the
Gram stain should be started

23. Treatment
The two main indications for surgery in acute
hematogenous osteomyelitis are
(1) the presence of an abscess requiring drainage
(2) failure of the patient to improve despite
appropriate intravenous antibiotic treatment

24. Surgery
The objective of surgery is to drain any abscess cavity
and remove all nonviable or necrotic tissue
 When a subperiosteal abscess is found in an infant,
several small holes should be drilled through the cortex
into the medullary canal
If intramedullary pus is found, a small window of bone
is removed
The skin is closed loosely over drains, and the limb is
splinted
 The limb is protected for several weeks to prevent
pathological fracture

25. Complications
Septicemia and pyemia
Septic arthritis
Chronic osteomyelitis
Pathological fractures
Growth disturbances