Osteomyelitis is a bacterial infection of bone that is most commonly caused by Staphylococcus aureus. Symptoms vary depending on age but may include fever, pain, and limping. Diagnosis involves blood cultures, bone biopsy, and imaging tests like MRI. Treatment requires prolonged antibiotic therapy along with surgical drainage of abscesses. Outcomes are generally good if appropriate treatment is provided, but recurrence can occasionally occur.

1. Osteomyelitis
Gesit Mtaferia (MD)

2. Osteomyelitis
• Etiology
• Bacteria are the most common pathogens
• Staphylococcus aureus is the most common infecting organism in all age
groups
• GBS and Escherichia coli - neonates
• After 6 yr of age- caused by S. aureus, streptococcus, or Pseudomonas
aeruginosa
• Pseudomonas infection - puncture wounds of the foot
• Salmonella species ,S. pneumoniae and S. aureus - children with sickle cell
anemia

3. Etiology….
• A microbial etiology is confirmed in ∼60% of cases of osteomyelitis.
• Blood cultures are positive in ∼50% of patients
• Prior antibiotic therapy and the inhibitory effect of pus on microbial
growth might explain the low bacterial yield

4. Epidemiology
• The median age is ∼6 yr
• The incidence of in children is estimated to be 1 : 5,000.
• More common in boys than girls
• The majority of osteomyelitis cases in previously healthy children are
hematogenous
• Minor closed trauma is a common preceding event in cases of osteomyelitis,
occurring in ∼30% of patients.
• Infection of bones can follow penetrating injuries or open fractures
• Bone infection following orthopedic surgery is uncommon
• Impaired host defenses also increase the risk of skeletal infection

5. MICROORGANISMS ISOLATED FROM PATIENTS WITH OSTEOMYELITIS AND THEIR CLINICAL ASSOCIATIONS

6. Pathogenesis
• In the metaphysis, nutrient arteries branch into nonanastomosing
capillaries under the physis
• Blood flow in this area is “sluggish,” predisposing to bacterial invasion
• Once a bacterial focus is established, phagocytes migrate to the site
and produce an inflammatory exudate (metaphyseal abscess)

7. Pathogenesis….
• As the inflammatory exudate progresses, pressure increases spread
through the porous metaphyseal space via the haversian system and
Volkmann canals into the subperiosteal space.
• Purulence beneath the periosteum may lift the periosteal membrane
of the bony surface, further impairing blood supply to the cortex and
metaphysis
• In newborns and young infants, transphyseal blood vessels connect
the metaphysis and epiphysis, so it is common for pus from the
metaphysis to enter the joint space

8. Clinical Manifestations
• The earliest signs and symptoms of osteomyelitis, often subtle and
nonspecific, are generally highly dependent on the age of the patient.
• Neonates might exhibit pseudoparalysis or pain with movement of
the affected extremity (e.g., diaper changes).
• Older infants and children are more likely to have fever, pain, and
localizing signs such as edema, erythema, and warmth.
• With involvement of the lower extremities, limp or refusal to walk is
seen in approximately half of patients.

9. Clinical Manifestations….
• Pelvic osteomyelitis can manifest with subtle findings such as hip,
thigh, or abdominal pain
• Long bones are principally involved in osteomyelitis
• femur and tibia are together constitute almost half of all cases
• Upper extremities account for one fourth of all cases.
• Flat bones are less commonly affected

10. Clinical Manifestations…
• There is usually only a single site of bone or joint involvement.
• Several bones are infected in <10% of cases; the exception is
osteomyelitis in neonates,
• Children with subacute symptoms and focal finding in the
metaphyseal area (usually of tibia) might have a Brodie abscess, with
radiographic lucency and surrounding reactive bone.

11. Diagnosis
• The diagnosis of osteomyelitis is clinical; blood cultures should be
performed in all suspected cases
• aspiration or biopsy of bone or subperiosteal abscess for Gram stain,
culture, and bone histology
• No specific laboratory tests for osteomyelitis
• WBC,ESR, orCRP are elevated

12. Diagnosis….
• Radiographic Evaluation
• Radiographic studies play a crucial role in the evaluation of
osteomyelitis
• MRI has emerged as the most sensitive and specific test and is widely
used for diagnosis
• long bones do not show lytic changes for 7-14 days after onset of
infection
• Infection in flat and irregular bones can take longer to appear.

13. Diagnosis….
• MRI is more sensitive than CT or radionuclide imaging in acute
osteomyelitis and is the best radiographic imaging technique for
identifying abscesses and for differentiating between bone and soft-
tissue infection
• Radionuclide imaging can be valuable , especially early in the course
of infection and/or multiple foci

14. Differential Diagnosis
• cellulitis or trauma (accidental or abuse)
• Myositis or pyomyositis
• Appendicitis, urinary tract infection, and gynecologic disease
• leukemia
• Neuroblastoma
• Primary bone tumors

15. Treatment
• Optimal treatment of skeletal infections requires collaborative efforts
of pediatricians, orthopedic surgeons, and radiologists.
• Antibiotic Therapy
• The initial empirical antibiotic therapy is based on knowledge of likely
bacterial pathogens at various ages, the results of the Gram stain of
aspirated material, and additional considerations.

16. Treatment….
• Duration of antibiotic therapy is individualized depending on the
organism isolated and clinical course.
• For most infections including those caused by S. aureus, the minimal
duration of antibiotics is 21-28 days, a total of 4-6 wk of therapy may
be required.
• Changing antibiotics from the intravenous route to oral
administration when a patient's condition clearly has improved and
the child is afebrile for ≥48-72 hr, may be considered.

17. Treatment….
• Surgical Therapy
• When frank pus is obtained from subperiosteal or metaphyseal
aspiration surgical drainage usually indicated
• Treatment of chronic osteomyelitis consists of surgical removal of
sinus tracts and sequestrum, if present.
• Antibiotic therapy is continued for several months or longer until
clinical and radiographic findings suggest that healing has occurred.
• Physical Therapy
• The major role of physical medicine is a preventive one

18. Prognosis
• When pus is drained and appropriate antibiotic therapy is given, the
improvement in signs and symptoms is rapid
• Recurrence of disease and development of chronic infection after
treatment occur in <10% of patients
• Long-term follow-up is necessary with close attention to range of
motion of joints and bone length

19. Septic Arthritis
• In infants and children has the potential to cause permanent disability
•Etiology
Haemophilus influenzae type b accounted for more than half of all
cases
Staphylococcus aureus - in all age groups
S. pneumoniae is most likely in the first 2 years of life
Group B streptococcus - in neonates
Fungal infections - as part of multisystem disease

20. Epidemiology
• More common in young children
• Half of all cases occur by 2 yr of age and 3/4 of all cases occur by 5 yr
of age
• Adolescents and neonates are at risk of gonococcal septic arthritis
• The majority of infections in otherwise healthy children are of
hematogenous origin

21. Epidemiology….
• Infection of joints can follow penetrating injuries , arthroscopy,
prosthetic joint surgery, intra-articular steroid injection, and
orthopedic surgery
• Immunocompromised patients and those with rheumatologic joint
disease are also at increased risk of joint infection

22. Pathogenesis
• Septic arthritis primarily occurs as a result of hematogenous seeding
• Less often, organisms enter the joint space by direct inoculation or
extension from a contiguous focus.
• Synovial and cartilage destruction results from a combination of
proteolytic enzymes and mechanical factors.

23. Clinical Manifestations
• Most septic arthritises are monoarticular
• The signs and symptoms depend on the age of the patient
• Early signs and symptoms may be subtle
• In neonates and young infants is often associated with adjacent
osteomyelitis
• Older infants and children might have fever and pain, with localizing
signs
• joints of the pelvis and lower extremities, limp or refusal to walk is
often seen
• Erythema and edema of the skin and soft tissue overlying the site

24. Clinical Manifestations
• Septic arthritis of the hip is an exception because of the deep location
of the hip joint
• Joints of the lower extremity constitute 75% of all cases of septic
arthritis
• The elbow, wrist, and shoulder joints are involved in about 25% of
cases

25. Diagnosis
• Blood cultures
• Aspiration of the joint fluid and anlysis
• white blood cell count and differential, ESR, and CRP
• Radiographic studies play a crucial role in evaluating septic arthritis.
• Conventional radiographs, ultrasonography, CT, MRI, and radionuclide
studies can all contribute to establishing the diagnosis

26. Treatment
• Optimal treatment of septic arthritis requires cooperation of pediatricians,
orthopedic surgeons, and radiologists to benefit the patient.
• Antibiotic Therapy
• The initial empirical antibiotic therapy is based on likely pathogens at
various ages, Gram stain
• Duration of antibiotic therapy
Ten to 14 days is usually adequate for streptococci, S. pneumoniae, and K.
kingae;
longer therapy may be needed for S. aureus and gram-negative infections
Oral antibiotics can be used to complete therapy once the patient is
afebrile for 48-72 hr

27. Treatment….
• Surgical Therapy
• Infection of the hip is generally considered a surgical emergency
because of the vulnerability of the blood supply to the head of the
femur
• For joints other than the hip, daily aspirations of synovial fluid may be
required

28. Prognosis
• When pus is drained and appropriate antibiotic therapy is given, the
improvement in signs and symptoms is rapid.
• Failure to improve or worsening by 72 hr requires review of the
appropriateness of the antibiotic therapy, the need for surgical
intervention
• Recurrence and chronic infection after treatment occur in <10% of
patients.