Paediatric Osteomyelitis and Pyomyositis

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DR SHEHU M

LECTURER/ PAEDIATRICIAN

DEPARTMENT OF SURGERY

BHUTH, JOS

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OUTLINE

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• Introduction
• Etiology
• Pathophysiology
• Clinical Presentation
• Laboratory investigations
• Treatment
• Complications
• Summary

INTRODUCTION

• Osteomyelitis is inflammation of the bone and marrow caused by an infecting organism

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• 1/10000 - 1/ 20 000

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• 1 in 5000 children younger than 13 years old

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• mean age 6.6 years

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• 2.5 times more common in boys

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• more common in the first decade of life due to the rich metaphyseal blood supply and immature immune system

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• not uncommon in healthy children

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• Pre antibiotic era 20-50 mortality

ETIOLOGY

• Staph aureus

• Group B Strep

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• Kingella kingae

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• Pseudomonas

• H. influenza

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• Mycobacteria tuberculosis

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• Salmonella

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PATHOPHYSIOLOGY

• local trauma and bacteremia lead to increased

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susceptibility to bacterial seeding of the metaphysis

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• history of trauma is reported in 30% of patients

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acute osteomyelitis

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• most cases are hematogenous

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• initial bacteremia may occur from a skin lesion

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• infection, or even trauma from tooth brushing

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PATHOPHYSIOLOGY

• sluggish blood flow in metaphyseal capillaries due

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to sharp turns results in venous sinusoids

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which give bacteria time to lodge in this region

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• the low pH and low oxygen tension around the

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growth plate assist in the bacterial growth�

• infection occurs after the local bone defenses have

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been overwhelmed by bacteria

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PATHOPHYSIOLOGY

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• spread through bone occurs via Haversian and

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Volkmann canal systems

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• purulence develops in conjunction with osteoblast

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necrosis, osteoclast activation, the release of

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inflammatory mediators, and blood vessel and

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thrombosis

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• a subperiosteal abscess develops when the purulence

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• breaks through the metaphyseal cortex

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PATHOPHYSIOLOGY

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• septic arthritis develops when the purulence breaks through an

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• intra-articular metaphyseal cortex (hip, shoulder, elbow, and

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ankle) (NOT KNEE)

• Infants <1 year of age can have infection spread across the

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growth plate via capillaries causing osteomyelitis in the

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epiphysis and septic arthritis

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• chronic osteomyelitis

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• periosteal elevation deprives the underlying cortical bone of blood

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• supply leading to necrotic bone (sequestrum)

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PATHOPHYSIOLOGY

• the necrotic bone which has become walled off

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• from its blood supply and can present as a nidus

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• for chronic osteomyelitis

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• an outer layer of new bone is formed by the

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• periosteum (involucrum)

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involucrum

• a layer of new bone growth outside existing bone seen in

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osteomyelitis

chronic abscesses may become surrounded by sclerotic bone

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and fibrous tissue leading to a Brodie's abscess

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Classification

• Acute osteomyelitis

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• Subacute osteomyelitis

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uncommon infection with bone pain and radiographic changes

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without systemic symptoms

increased host resistance, decreased organism virulence,

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and/or prior antibiotic exposure

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• Chronic osteomyelitis

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Clinical presentation

• History

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limb pain

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recent local infection or trauma

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limp or refusal to bear weight

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generally not toxic appearing

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+/- fever

Clinical presentation

• History

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limb pain

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recent local infection or trauma

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limp or refusal to bear weight

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generally not toxic appearing

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+/- fever

Clinical presentation

Physical exam

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• inspection & palpation

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edematous, warm, swollen, tender limb

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evaluate for point tenderness in pelvis, spine, or limbs

range of motion

restricted motion due to pain

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Lab Investigations

Radiographs

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recommended views

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• obtain AP and lateral of the suspected area

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findings

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early films may be normal or show loss of soft tissue planes and

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soft tissue edema

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• new periosteal bone formation (5-7 days)

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• osteolysis (10-14 days)

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• late films (1-2 weeks) show metaphyseal rarefaction

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(reduction in metaphyseal bone density) or possible abscess

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Lab Investigations

• Bone scan

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indications

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• nondiagnostic x-ray

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• need to localize pathology in infant or toddler with non-focal

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exam

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technetium-99m can localize the focus of infection and show

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a multifocal infection

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• 92% sensitivity

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a cold bone scan may be associated with more aggressive

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infections

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Lab Investigations

• CT

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indication

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• more helpful later in the disease course to demonstrate bone

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changes or abscesses

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• MRI

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• detects abscesses and early marrow and soft tissue edema

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indications

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• can assist with decision making when a poor clinical response

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to antibiotics or surgical drainage considered

Lab Investigations

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• WBC count

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• elevated in 25% of patients and correlates poorly with

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treatment response

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• C-reactive protein

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• elevated in 98% of patients with acute hematogenous

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osteomyelitis

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• becomes elevated within 6 hours

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• most sensitive to monitor therapeutic response

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• declines rapidly as the clinical picture improves

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Lab Investigations

• CRP is the best indicator of early treatment success and

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normalizes within a week

• failure of the C-reactive protein to decline after 48 to 72 hours

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of treatment should indicate that treatment may need to be altered

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• ESR

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• elevated in 90% of patients with osteomyelitis

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• rises rapidly and peaks in three to five days, but declines too

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slowly to guide treatment

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• less reliable in neonates and sickle cell patients

Lab Investigations

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• plasma procalcitonin

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• new serologic test that rises rapidly with a bacterial infection, but

remains low in viral infections and other inflammatory situations

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• elevated in 58% of pediatric osteomyelitis cases

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• bone aspiration

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helps establish a definitive diagnosis

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50% to 70% of affected patients have positive cultures

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• blood culture

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is positive only 30% to 50% of the time and will likely be negative soon

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after antibiotics are administered, even if treatment is not progressing

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satisfactorily

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Lab Investigations

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• Aspiration

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• assists in diagnosis and management

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• helps guide antibiotic selection when organism identified

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(50% of the time)

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• proceed with surgical drainage if pus is aspirated

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• Biopsy and culture

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consider when diagnosis not clear (i.e. subacute

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osteomyelitis) and need to rule out malignancy

Treatment

• Nonoperative treatment

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• antibiotic therapy alone

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indications

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• early disease with no subperiosteal abscess or abscess within

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the bone

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• surgery is not indicated if clinical improvement obtained within

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48 hours

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• antibiotics

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• generally, nafcillin or oxacillin,

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• MRSA (then use clindamycin or vancomycin)

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Treatment

• if gram stain shows gram-negative bacilli - add a third generation

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• cephalosporin

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• convert to organism-specific antibiotics if organism identified

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• mycobacterium tuberculosis

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• treatment for initial 1 year is multiagent antibiotics and rarely

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surgical debridement due to risk of chronic sinus formation

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• duration

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• typically treat with IV antibiotics for four to six weeks

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• intravenous versus oral

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• often a case by case decision with input from infectious

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disease consultation

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Treatment

• Operative treatment

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• surgical drainage, debridement, and antibiotic therapy

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• indications

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• deep or subperiosteal abscess

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• failure to respond to antibiotics

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• chronic infection

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• contraindications

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• hemodynamic instability,

Complications

• DVT

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• incidence

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• is an infrequent complication in children

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• risk factors

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• CRP > 6

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• surgical treatment

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• age > 8-years-old

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• MRSA

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Complications

• treatment

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therapeutic anticoagulation

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• Meningitis

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• Septic arthritis

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risk factors

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• bones with intra-articular metaphysis are at risk (shoulder,

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elbow, hip, ankle)

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• neonates

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treatment

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• irrigation and debridement

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Complications

• Growth disturbances and limb-length discrepancies from

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growth plate involvement

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treatment

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• observation and possible corrective surgery depending on

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severity or projected severity

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• Pathologic fractures

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• Prognosis

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• Mortality decreased from 50% to <1% with development of

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antibiotics

Osteomyelitis

INTRODUCTION

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• Pyomyositis is a purulent infection of skeletal

muscle that arises from hematogenous

spread, usually with abscess formation.

• Described by Zur 1885

EPIDEMIOLOGY

EPIDEMIOLOGY

RISK FACTORS

MICROBIOLOGY

• Staphylococcus aureus is the most common cause of pyomyositis
• 90 % of tropical cases, 75% percent of temperate cases.
• Group A streptococci is the second most common pathogen
• E. coli pyomyositis is an emerging infection among patients with hematologic malignancy.
• Pyomyositis can also be polymicrobia

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CLINICAL MANIFESTATION

• Fever
• Pain with cramping localized to a single muscle group
• Predilection muscle sites
• Recurrent infection
• Course of pyomyositis is variable
• Three clinical stages

Stage 1

• Only 2%
• < 10days
• Crampy local muscle pain, swelling, and low-grade fever.
• Induration of the affected muscle may be present
• A deep abscess may not be discretely palpable, but the muscle may have a "woody" texture on palpation
• Fluctuation is not present
• Pus -ve.
• Leukocytosis

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Stage 2

• 90 %
• 10 to 21 days
• Fever, muscle tenderness, and edema
• Abscess +ve
• Pus on aspiration
• Marked leukocytosis

Stage 3

• Severely ill/ toxic
• The affected muscle is fluctuant
• Rhabdomyolysis
• septic shock, endocarditis, septic
• emboli, pneumonia, pericarditis,
• septic arthritis, brain abscess,
• acute renal failure

DIFFERENTIAL DIAGNOSIS

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• Cellulitis

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• Deep vein thrombosis

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• Osteomyelitis

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• Diabetic muscle infarction

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• Spontaneous gangrenous myositis

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• septic arthritis

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• contusion, hematoma
• neoplasm

DIAGNOSIS

Management

Summary

• Osteomyelitis/ pyomyositis in the pediatric population is most

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often the result of hematogenous seeding of bacteria to the

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metaphyseal region of bone and muscle group respectively.

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• Diagnosis is generally made with X-ray studies/ Biopsy

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• Treatment is nonoperative with antibiotics in the absence of

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an abscess. Surgical debridement is indicated in the

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presence of an abscess for osteomyelitis.

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