9. Infections Flashcards by Thomas Etue

Diabetic, steroid-immunosuppressed, and
hemodialysis patients are particularly vulnerable
to

suppurative osteomyelitis

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mc source/spread of osteomyelitis

Hematogenous

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4 Major Pathways of Spread of Suppurative

Osteomyelitis:

Hematogenous
Spread from contiguous source of infection
Direct implantation
Postoperative infection (iatrogenic)

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Fever
Chills
Pain
Swelling
Loss of limb function
Elevated WBC
ESR, +CRP

Suppurative Infection Infants/Young Children

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Chronic, insidious process
Fever
Malaise
Edema
Erythema
Pain

Suppurative Infection

in Adults

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Boys between ages 2-12 are most

susceptible to

suppurative osteomyelitis

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Usually affects large tubular bones of

extremities

suppurative osteomyelitis

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Diaphyseal and metaphyseal vessels penetrate physis to enter epiphysis

Infantile Vascular Pattern of infection

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Physis becomes effective barrier around age

8-18 months

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High incidence of septic arthritis with epiphyseal

involvement in

infantile osteomyelitis

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Slow turbulent blood flow in metaphysis
rendering great environment for infection
with no metaphyseal vessels penetrating the
physis

Childhood Vascular Pattern of infection

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In adults communication between epiphysis and

metaphysis occurs via

blood vessels that

gradually penetrate physis as it fuses

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Increased intramedullary pressure in bone due to

pus formation

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Hyperemia adjacent to infarction that stimulates

osteoclastic activity resulting in

regional osteoporosis

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Infection penetrates endosteum entering Haversion systems crossing cortex to the

subperiosteal space

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Few Sharpe’s fibers attaching periosteum to cortex in children, thus periosteum is easily stripped away
from cortex which results in

periostitis aka periosteal reaction

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Cortical and medullary infarcts result in

Sequestrum

Dead bone

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to wrap or cover

involucrum

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defect in involucrum which decompresses bone by discharging inflammatory products
from bone

Cloaca

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Associated with chronic osteomyelitis and allows seeding of adjacent soft tissues

Cloaca

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Chronic ulcer with draining sinus, that has

become malignant

Marjolin Ulcer

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defined as the

malignant degeneration of a chronic wound or scar

Marjolin’s Ulcer

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On biopsy Marjolin’s Ulcer have been most commonly identified as

squamous cell and basal cell carcinomas

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If even remote clinical suspicion of bone

infection, do

bone scan or MRI

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MRI with and without Gd contrast is Excellent for Detecting

Infection

Soft tissue findings on plain film may be seen within | __ days of bacterial contamination of bone

Bone sequestrum occurs ~3-6 weeks after onset usually appear

sclerotic

90% of infections involve

extremities

Highest incidence of suppurative spondylitis occurs in

debilitated patients (50-60)

cortical erosion and | intramedullary sequestrum seen in

Chronic Osteomyelitis

mc complaint in spinal infection

Back pain

what % of the time is spinal infection misdiagnosed?

33%

- < 20 - Loss of disc height - Paraspinal edema (abscess) - Endplate destruction patchy lysis of vertebral body

disc infection

Initial focus of Irregularity and radiolucency at anterior vertebral endplate

Adult Spondylitis

a spreading diffuse | inflammatory process with formation of suppurative/purulent exudates or pus.

Phlegmon

Localized aborted form of suppurative osteomyelitis

Brodies Abscess

Presentation mimics osteoid osteoma with localized limb pain that is nocturnal; alleviated by aspirin

brodies abscess

Usually have had distant infection that has seeded to bone and mc male children

Brodies Abscess

what is mc found with Brodies Abscess, | however lesion may be sterile

Staphylococcus Aureus

Oval, elliptical, serpiginous, radiolucency with | margin of heavy reactive sclerosis usually >1.0cm

Brodies Abscess

Brodies abscess MRI findings

Variable signal internally, with low signal of marginal sclerosis (penumbra sign)

Eccentrically located radiolucent lesion crossing the epiphyseal plate

Brodies Abscess: | Subacute osteomyelitis

Proper ID of pathogen is essential for TX of

Chronic Osteomyelitis (MC Staphylococcus aureus)

Sclerosis, cortical thickening, periosteal reaction | (laminated or solid), lysis, sequestra

Chronic Osteomyelitis

Why might antibiotics not help much for chronic osteomyelitis?

blood supply is separated from organisms due to bone fragmentation

Leading cause of death in Western Society at | beginning of 20th Century from Inhalation of Mycobacterium tuberculosis

Non-Suppurative Osteomyelitis: | Tuberculosis (TB)

Infection of the musculoskeletal system from TB is | commonly caused by

hematogenous spread of primary pulmonary focus

Insidious back pain, decreased ROM, focal tenderness NOT accompanied by fever, night sweats, toxicity, or prostration

Non-Suppurative Osteomyelitis: | Tuberculosis (TB)

sudden onset of lower limb paraplegia

Pott’s Paraplegia

70% of TB patients are

<5yo

Pott’s Paraplegia is associated with

Tubercular Spondylitis, aka

Pott’s Disease

Pott’s Disease is mc in

lower thoracic and upper lumbar spine

Pott’s Disease spreads via

Batson’s venous plexus

What is initially involved, in Pott's disease?

Subchondral anterior vertebral endplate

Tubercular Spondylitis: Pott’s Disease, spreads by into the disc by

direct extension into disc as vertebral body | collapse occurs

* Abscess formation * Subligamentous dissection * Granulomatous formation * May cause Pott’s paraplegia

Paravertebral soft tissue involvement from Pott’s Disease

Calcification of psoas abscess indicates

healing of abscess in muscle and inactivity of | infection

Computed tomographic scan of the abdomen showing a left iliopsoas abscess (arrow) that likely originated from

tuberculous osteomyelitis

Extensive paraspinal abscess formation with little osseous involvement

Subligamentous Dissection

Produces shallow erosion of anterior vertebral body that resembles lymph node or aortic aneurysm erosion

Subligamentous Dissection

Subligamentous extension may lead to Pott’s disease (disc space narrowing with vertebral collapse) resulting in

Gibbus Deformity

Subligamentous extension may lead to Pott’s disease (disc space narrowing with vertebral collapse) resulting in

Gibbus Deformity

Advanced TB causing multiple level collapse with infection and disc deterioration

Pott’s Paraplegia

75% of Tubercular Arthritis affect

hip and knee

Initial lesions of Tubercular Arthritis simulate

RA since affects bare | areas of joint initially

– Nonuniform destruction of joint – Cartilage and bone destruction with sequestrum formation

Tubercular Arthritis

Low grade TB results in hyperemia which causes

localized osteoporosis

21 days latent radiographic period, Early changes include lytic destructive lesion places in anterior corner of vertebral endplate, coupled with loss of disc space height

Tubercular Spondylitis

Displacement of paraspinal line (extrapleural sign) | and Usually affects TL junction, usually L1

Tubercular Spondylitis

Pear shaped configuration that frequently calcifies

Tubercular Spondylitis

Vertebral body lysis results in pathologic vertebral body collapse, coupled with disc destruction and inability to visualize discs

Tubercular Spondylitis

Angular kyphotic deformity aka

Gibbus Deformity

Gibbus Deformity may cause ____ vertebra

tall

tubercular arthritis shoes early

joint widening due to effusion

- Early joint widening due to effusion - Subchondral bone destruction - Articular cartilage destruction - joint space narrowing - periarticular osteoporosis

Tubercular Arthritis:

End stage tubercular spondylitis is

fibrous ankylosis of joint

Bony ankylosis and periosteal reaction is common in

pyogenic infection

Management of skeletal TB includes

debridement and arthrodesis

Diffuse soft tissue swelling, bone expansion, and thinning of cortex

spina ventosa in Tuberculous Dactylitis

9. Infections Flashcards

(80 cards)