Download BONE AND JOINT INFECTIONS

Infection in Bone and Joint
Presented By:
Fadel Naim M.D.
Orthopedic Surgeon
IUG
Osteomyelitis
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osteon (bone)
myelo (marrow)
itis (inflammation)
Inflammation and destruction of bone
caused by aerobic and anaerobic
bacteria, mycobacteria, and fungi
The term osteomyelitis does not specify the
causative organism or the disease process
Epidemiology
Common in young children
 Common with malnutrition, immunodeficiency
- with decreased resistance of the patient
 Boys> girls
 History of trauma
 Decreasing in incidence & severity & mortality
with advent of newer antibiotics

Osteomyelitis
Classification:

Duration
Acute, Subacute or Chronic

Route of infection Hematogenous or Exogenous

Host response
Pyogenic or Granulomatous
Acute Pyogenic Osteomyelitis
infants
Staphylococcus aureus, Streptococcus
agalactiae, Escherichia coli
children over
one year
Staphylococcus aureus, Streptococcus
pyogenes, and Haemophilus influenzae
adults
Staphylococcus aureus
Source Of Infection
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Hematogenous
spread
Direct inoculation
Contiguous focus
of infection
 The
most common site is
the rapidly growing and
highly vascular
metaphysis of growing
bones
– The apparent slowing or
sludging of blood flow as
the vessels make sharp
angles at the distal
metaphysis
predisposes the vessels to
thrombosis
 the bone itself to localized
necrosis and bacterial
seeding
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The joint is usually
spared from infection
unless the metaphysis
is intracapsular, as is
found in the proximal
part of:
– The radius
– The humerus
– The femur
Age variation
Neonates:

Extensive bone necrosis

Increased ability to absorb large sequestrum

Increased ability to remodel

Epiphysio-metaphyseal vascular connection
– leading to secondary septic arthritis
Age variation
Adults:

No subperiosteal abscess due to adherent
periosteum
– Soft tissue abscess

Vascular connection with the joint leading to
secondary septic arthritis
Clinical Pictures
Pain, restless
 Malaise and fever
 The limb is held still
(pseudo paralysis)
 Sometimes mild or
absent (neonates)

Acute Osteomyelitis
Diagnosis
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History and clinical examination
CBC, ESR, B.C.
X-ray (normal in the first (10-14) days
Ultrasound
Bone Scan Tc 99, Gallium 67
MRI
Aspiration
Radiographic Findings
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Usually reflect the destructive process
but lag at least two weeks behind the
process of infection
The earliest changes are:
– Swelling of the soft tissue
– Periosteal thickening and/or
elevation
– Focal osteopenia

At least 50% to 75% of the bone
matrix must be destroyed before
radiographs show lytic changes
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(A) Proximal humerus at day 1 of infection - no visible changes.
(B) Proximal humerus at day 12 of infection
Plain-film radiograph
showing osteomyelitis of
the second metacarpal
(arrow).
 Periosteal elevation,
cortical disruption and
medullary involvement
are present.
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
The above X-ray of the left
ankle of a 10-year-old boy
shows lucency in the tibial
metaphysis secondary to
acute hematogenous
osteomyelitis (AHO).
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The above X-ray of the right
ankle of a 10-year-old boy
shows lucency in the tibial
metaphysis secondary to
acute hematogenous
osteomyelitis (AHO).
Here is an X-ray of an AHO lesion extending into the growth plate

MRI :
Radiological studies
Early detection and surgical localization of
osteomyelitis.
Sensitivity ranges from 90-100%.

Radionuclide bone scanning :
A 3-phase bone scan with technetium 99m is
probably the initial imaging modality of
choice
Show increase activity but it is a non
specific sign of inflamation.
This MRI sagittal section shows the
same AHO lesions with the right lesion
extending into the growth plate.
Bone scans, both anterior (A) and lateral (B), showing the
accumulation of radioactive tracer at the right ankle (arrow).
This focal accumulation is characteristic of osteomyelitis.
Labratory

The leukocyte count (WBC), erythrocyte
sedimentation rate (ESR), and C-reactive
protein level (CRP) should be monitored
– At the time of admission
– During treatment
– During follow-up

In all patients with osteomyelitis on a weekly
basis
Diagnosis requires 2 of the 4 following criteria:
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Purulent material on aspiration of affected bone
Positive findings of bone tissue or blood culture
Localized classic physical findings of bony
tenderness, with overlying soft-tissue erythema or
edema
Positive radiological imaging study
Differential Diagnosis
Acute Septic Arthritis
 Acute monoarticular
rheumatoid arthritis
 Sickle cell crisis
 Cellulitis
 Ewing’s Sarcoma

Complications
Septicemia & metastatic abscesses
 Septic arthritis
 Growth disturbance (children)
 Pathological fracture
 Chronic osteomyelitis
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SUBACUTE OSTEOMYELITIS
Subacute Osteomyelitis
Results from a less virulent Microorganism,
or a patient with an elevated resistance.
 Occurs Mostly at the Distal Femur or
Proximal Tibia
 On X-Ray: Brodie’s Abcess

 Small and Oval in shape
 It is surrounded by sclerotic bone
 May be mistaken for Ostieoid Osteoma
Subacute Osteomyelitis
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An image depicting subacute osteomyelitis
Chronic Osteomyelitis

The coexistence of infected, nonviable
tissues and an ineffective host response
leads to the chronicity of the disease
Chronic Osteomyelitis
Factors responsible for chronicity
Local factors: Cavity, Sequestrum, Sinus,
Foreign body, Degree of bone necrosis
 General: Nutritional status of the involved
tissues, vascular disease, DM, low immunity
 Organism: Virulence
 Treatment: Appropriateness and compliance
 Risk factors: Penetrating trauma, prosthesis,
Animal bite
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Pathologic features of chronic osteomyelitis
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Sequestrum:
When both the medullary and the periosteal blood
supplies are compromised, large areas of dead bone
(sequestra) may be formed
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Involucrum:
New bone forms from the surviving fragments of
periosteum and endosteum in the region of the
infection to form an encasing sheath of live bone
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sinus tract:
A bone cavity may persist or the space may be filled
with fibrous tissue, which may connect with the skin
surface by the sinus tract
Sequestrum
Chronic Osteomyelitis
Types
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A complication of acute Osteomyelitis

Post traumatic

Post operative
Chronic Osteomyelitis
Low grade fever, if present
 ESR usually elevated, reflecting chronic
inflammation
 The blood leukocyte count ( WBC ) is
usually normal
 If a sinus tract becomes obstructed, the
patient may present with a localized
abscess and/or an acute soft-tissue
infection

Chronic Osteomyelitis
Organism
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Usually mixed infection
Mostly staph. Aureus E. Coli . strep
pyogen, proteus
Treatment of Osteomyelitis
A
close interaction between various
specialists is important to improve
the management of this disease
– Orthopaedic surgeons
– Plastic and vascular surgeons
– Infectious disease specialists
Treatment of Osteomyelitis
1.
2.
3.
4.
5.
6.
7.
Adequate drainage
Thorough débridement
Obliteration of dead space
Wound protection
Specific antimicrobial coverage
Correcttion of host defects
Improving the nutritional, medical, and
vascular status of the patient
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Good nutrition
Smoking cessation
Control of specific diseases such as diabetes
Bone Stabilization
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If skeletal instability is present measures must be taken
to achieve stability with plates, screws, rods, and/or an
external fixator.
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External fixation is preferred over internal fixation.
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Ilizarov external fixation:
– allows reconstruction of segmental defects and difficult infected
nonunion.
– An extended period of treatment with the device, averaging 8.5
months.
– The sites of the wires or pins usually become infected and the
device is painful.
Soft-tissue Coverage
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Adequate soft-tissue coverage of the bone is necessary
to arrest osteomyelitis
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Small soft-tissue defects may be covered with a splitthickness skin graft
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For large soft-tissue defects or an inadequate softtissue envelope, local muscle flaps and free
vascularized muscle flaps may be placed in one or two
stages
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Healing by so-called secondary intention should be
discouraged
Septic Arthritis
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Septic arthritis :
– Direct invasion of joint space by a
variety of microorganisms,
including a variety of bacteria,
viruses, mycobacteria, and fungi.
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Reactive arthritis:
– A sterile inflammatory process,
may be the consequence of an
infectious process located
somewhere else in the body.
Septic Arthritis
 50%
of cases in children <3
years
 The hip joint is the common site
in <3years, whereas the knee
joint is more common in older
children.
 7.8
cases per 100,000 person-years
 The incidence of gonococcal arthritis is
2.8 cases per 100,000 person-years
 Septic arthritis is becoming increasingly
common among people who are
immunosuppressed and elderly people
who have a variety of co-morbid
diagnoses

Most of these infections occur in very
young and very old people and among
people who abuse intravenous drugs
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The most commonly involved joint:
– Knee (50%)
– Hip (20%)
– Shoulder (8%)
– Ankle, and wrists (7% each)
– Elbow, interphalangeal,
sternoclavicular, and sacroiliac joints
each make up 1-4% of cases
Risk Factors
 Corticosteroids-33%
 Existing
arthritis-24%
 Infection elsewhere-22%
 DM-13%
 Trauma-12%
 None-8%
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Two major classes :
– Gonococcal
– Nongonococcal

Neisseria gonorrhoeae remains the most frequent
pathogen (75% of cases) among younger sexually
active individuals
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Staphylococcus aureus is the most common cause of
the vast majority of cases of acute bacterial arthritis in
adults and children older than 2 years

Organisms may
invade the joint by:
– Direct inoculation
– Contiguous spread
from infected
periarticular tissue
– Bacteremia (the
most common route)
Acute Septic Arthritis
Differential Diagnosis
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Acute osteomyelitis
Trauma
Irritable joint
Hemophilia
Rheumatic fever
Gout
Diagnosis
History
Because joint infections are uncommon, be
attentive to features of the patient's history
that may indicate an infectious process and
not a primary rheumatological or orthopedic
process
Inspection
Thorough inspection of
all joints for signs of
inflammation is
essential for
diagnosing infection :
– Erythema
– Swelling (90% of cases)
– Warmth
– Tenderness
– Limitation of both active
and passive ROM
Synovial Fluid Examination
Leukocyte count
 Appearance on gram stain
 Polarizing microscopy
examination
 Culture of the fluid
 Culture of the synovial
fluid or of synovial tissue
itself is the only definitive
method of diagnosing
infective arthritis

Imaging Studies
 Plain
radiographs of some limited value
in evaluating a joint for infection
– Radiographs are most useful in ruling out
underlying osteomyelitis or periarticular
osteomyelitis resulting from the joint
infection itself
– Periarticular soft tissue swelling is the
most common finding
 Ultrasonography
may be used to
diagnose effusions
Acute Septic Arthritis
Treatment
– Aspiration
– Antibiotics
– Splintage
– Surgical drainage
– Treatment of complications
Management of Infective Arthritis
 Management
of infective arthritis focuses
on:
– Adequate and timely drainage of the
infected synovial fluid
– Administration of appropriate antimicrobial
therapy

Usually, the antibiotic must be administered parenterally
for 3-4 weeks, but each case needs to be evaluated
individually
– Immobilization of the joint to control pain
Drainage

The choice of the type of drainage, whether
percutaneous or surgical, has not been resolved
completely

Aspirating the joint 2-3 times a day may be necessary
during the first few days
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Surgical drainage is indicated:
– For the appropriate choice of antibiotics
– Vigorous percutaneous drainage fails to clear the infection
after 5-7 days
– The infected joints are difficult to aspirate (eg, hip)
– Adjacent soft tissue is infected
Prognosis
50% of adults with septic arthritis have
significant sequelae of decreased ROM or
chronic pain after infection
 poor outcome in the following:

– Age older than 60 years
– Infection of the hip or shoulder joints
– Underlying rheumatoid arthritis
– Positive findings on synovial fluid cultures after
7 days of appropriate therapy
– Delay of 7 days or more in instituting therapy