Osteomyelitis

2.  Osteomyelitis is the inflammation of the bone or BM
caused by an infecting organism.
 Micro-Organisms may reach bones via the Bloodstream
or by Direct Invasion. (e.g : skin puncture, operation,
open fracture)
 Factors which affects it’s development
◦ Virulence of the organism involved
◦ Host Factors (Age, Immunity, Diseases)
◦ Local factors (site of Involvement, damaged muscle
presence of foreign material , vascularity)

3.  It can be classified on the basis of the causative
organism, the route, duration and anatomic location of
the infection.
 According to duration: acute, subacute, chronic
 In children, osteomyelitis most commonly affects the
long bones of the legs and upper arms.
 Adults are more likely to develop osteomyelitis in the
vertebrae.
 Diabetic patients may develop osteomyelitis in their feet
if they have foot ulcers.
 Osteomyelitis usually begins as an acute infection, but it
may evolve into a chronic condition.

5. 1. Hematogenous Osteomyelitis
• Bacterial seeding from the blood.
• Seen primarily in Children.
• The most common site
 Metaphysis at the growing end of Long Bones in Children
 Vertebrae in Adults; involving two adjacent vertebrae
with intervertebral disk (may occur pelvis, long bones
and clavicle)
2. Direct Inoculation Osteomyelitis
• Its osteomyelitis complicating open fracture or surgical
operation, in which organisms gain entry directly through
the wound.
• Tend to involve multiple organisms. but mainly S.Aureus

7.  Staph. aureus (Most common)
 H.Influenzae (Young Children) (6 week to 4
yrs)
but still, the most common causative organism for
osteomyelitis in young children is staphylococcus
aureus
H.flu infection has become less common due to
vaccination.
 Salmonella infection common in Sickle-Cell
anaemia patients.
 Pseudomonas infection –Most common in IV
drug abusers.
 Fungal OM usually seen in chronically ill patients

8. PATHOMECHANISM
Organisms reach the bone through the blood stream from a septic focus
elsewhere in the body – for instance from a boil in the skin.
Infection begins in the metaphysis of a long bone, which must be presumed to
form a productive medium for bacterial growth.
Acute inflammatory reaction occurs
Pus is formed and soon finds its way to the surface of the bone where it forms a
subperiosteal abscess
Later the abscess may burst into the soft tissues and may eventually reach the
surface to form a sinus.
Blood supply to a part of the bone is cut off by septic thrombosis ofthe vessels .
The ischaemic bone dies and eventually separates from the surrounding
living bone as a sequestrum.
New bone is laid down beneath the stripped-up periosteum, forming an
investing layer
known as the involucrum.

10.  The metaphysis has relatively fewer
phagocytic cells than the physis or diaphysis,
allowing infection to occur more easily in this
area. A resulting abscess breaks through the
thin metaphyseal cortex, forming a
subperiosteal abscess.

11. 1. Inflammation.
• Earliest Change
• Increase interaosseous pressure leads to Pain.
2. Suppuration
• Pus at medulla >> Volkmann canals>>Surface >>
Subperiosteal Abscess>> spread along the shaft>> burst
into the soft tissue
• May extend to Epiphysis in Neonates and Children.
• May extend to Interverteberal Discs in Adults.
3. Necrosis/Sequestrum
• Begin in a week.
• causes : increase in intraosseous pressure, vascular stasis,
infected thrombosis, periosteal stripping which increasingly
compromise blood supply

12. 4. New-bone formation
• New bone formation from the stripped surface of
periosteum
• Bone thickens to form an involucrum enclosing the infected
tissue.
5. Resolution
bone will heal if infection is controlled and intraosseous
pressure is released, though it may remain thickened. or
progress to complications

14. Does infection crosses
PHYSIS ?
or
Does it involves JOINTS
?

15.  In children younger than 2 years, some
blood vessels cross the physis and may
allow the spread of infection into the
epiphysis. For this reason, infants are
susceptible to limb shortening or angular
deformity if the physis or epiphysis
is damaged by infection. Otherwise, the
physis acts as a barrier that prevents the
direct spread of a metaphyseal abscess
into the epiphysis.

16.  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, however, the diaphysis is at greater
risk in these patients.

17.  After the physes are closed, acute hematogenous
osteomyelitis is much less common.
Hematogenous seeding of bone in adults is often
seen in a compromised host. Although it can occur
anywhere and in any part of the bone, generally the
vertebral bodies are affected. In these patients,
abscesses spread slowly and large sequestra rarely
form. If localized destruction of cortical bone
occurs, pathologic fracture can result.

18.  Spread of infection to a contiguous joint
also is affected by the patient’s age. In
children younger than 2 years, the common
blood supply of the metaphysis and
epiphysis crosses the physis and can allow
spread of a metaphyseal abscess into the
epiphysis and eventually into the joint.
 The hip joint is the most commonly affected
in young patients; however, the physes of
the proximal humerus, radial neck, and
distal fibula also are intraarticular, and
infection in these areas can lead to septic
arthritis as well.

19.  In older children, this common circulation is
no longer present, and septic arthritis is rare.
After the physes are closed, infection can
extend directly from the metaphysis into the
epiphysis and involve the joint.
Septic arthritis resulting from acute
hematogenous osteomyelitis is generally seen
only in infants and adults.

20.  Fever , chills and Malaise
 Pain
 Tenderness, Redness, Edema, Warmth (signs of
inflammation)
 Restricted Joint Movement
History preceding Skin Lesion or Sore Throat.
Typically; child, boy. The bones most commonly
affected are the tibia, the femur and the humerus. The onset is rapid. The
child
complains of feeling ill, and of severe pain over the affected bone. There
may be
a history of recent boils or of a minor injury.

21. 1. Lab studies
• CBC: leucocytosis
• Elevated CRP & ESR (nonspecific).
• Blood Culture
• Culture & sensitivity test; by aspiration from the
subperiosteal abscess, +ve in only 50% of patients with
hematogenous osteomyelitis.
2. Radiological studies
• X-ray
• MRI
• Radionuclide bone scanning
• CT scan
• US

22. • 1st 10 days Show No Abnormality .
Only after two or three weeks do visible changes appear, and they
may never do so if efficient treatment is started very early.
• By the end of the 2nd Week signs of rarefaction of
Metaphysis and New Bone Formation. Then sigs of
healing
• Soft-tissue edema at 1-3 days after start of infection.
• Bony changes are not evident for 14-21 days:
– Early radiographic signs of rarefraction (thining of
bony tissue sufficient to cause decreased density of
bone) of the metaphysis and new bone formation
outlining the raised periosteum
– Sclerosis and thickening of the bone cortex at
healing
• Approximately 40-50% focal bone loss is necessary to
cause detectable lucency on plain films; a negative X-
Ray does not exclude osteomyelitis

24. Plain-film radiograph showing
osteomyelitis of the 2nd
metacarpal
• Periosteal elevation
• Cortical disruption
• Medullary involvement.

25.  X-ray of the left ankle of
a 10-year-old boy shows:
 Lucency in the tibial
metaphysis secondary to
acute hematogenous
osteomyelitis (AHO).

26. MRI
• Early detection and surgical localization of osteomyelitis.
• sensitivity 90-100%
• help to distinguish between Bone and Soft-Tissue Infection.
• now superseded isotope scanning as it provides more
anatomical information on the infection.
MRI sagittal section
shows the same
AHO lesions with
the right lesion
extending into the
growth plate.

27. Radionuclide bone scanning
• A 3-phase bone scan with technetium 99m is probably
the initial imaging modality of choice. VS reserved for
the diagnosis of bone infection in the less clinically
accessible sites such as the hip, pelvis and spine.
• Show increase activity (non specific sign of
inflamation).
Accumulation of isotope depends upon the rate of bone
turnover and its vascuarity, so that in the early stages
of disease inadequate blood supply may result in a
‘cold’ lesion. More commonly, within a few hours or
days of the onset of symptoms there is an increased
uptake of isotope, giving a ‘hot’ scan at the site of the
bone lesion.

28. A. Anterior view B. lateral view
 Both showing the accumulation of radioactive
tracer at the right ankle (arrow). This focal
accumulation is characteristic of osteomyelitis.

29. CT scan
• Spinal vertebral lesions
• Complex anatomy (pelvis, sternum & calcaneus)
Ultrasound
• In children with acute osteomyelitis.
• May demonstrate early changes, 1-2 days after onset of
symptoms.
• Shows soft tissue abscess, fluid collection & periosteal
elevation.
• Ultrasonography allows for ultrasound-guided aspiration.
• It does not allow for evaluation of bone cortex.

30.  Criteria (2 of 4):
1. Localized classic physical findings (tenderness,
erythema or edema).
2. Purulent material on aspiration of affected
bone.
3. Positive findings of bone tissue or blood
culture.
4. Positive radiological imaging study.

31. 1. Analgesia
2. Rest of the affected part
3. Antibiotic treatment.
 IV antibiotics for 1-2 weeks then oral for 3-6
weeks.
 Cultures & sensitivity test.
 Why systemic ? To ensure high blood levels.
 Initially broad-spectrum antibiotics such as a third-
generation cephalosporin combined with a synthetic
penicillin is used, but as soon as the causative
organism has been identified the antibiotic to which
it is most sensitive should be ordered.
 MRSA- Use vancomycin instead of the penicillin.
 Antibiotics should be continued for at least 4 weeks,
even when the response has been rapid.

32. Nade in 1983 proposed 5 principles for Acute
hematogenous OM that are still applicable.
1. Appropriate antibiotic is effective before
abscess formation
2. Antibiotics do not sterilise avascular tissues
or abscess, these require surgical removal.
3. If such removal is effective, antibiotics
prevents its reformation.
4. Surgery shoul not damage further ischaemic
bone and soft tissue.
5. Antibiotics to be continues after surgery.

33. ◦ Debridement
◦ Drainage of subperiosteal abscess
◦ Operation may be unnecessary if effective antibiotic
treatment can be begun within 24 hours of the onset of
symptoms, but in practice diagnosis is not always so
prompt, and in that event it seems wiser to undertake
early operation, in order to release pus and to relieve
pain, which is often severe. This should definitely be
performed if there has not been a marked improvement
to the antibiotic treatment within 48 hours.