Bone and Joint Infection

Prof. Mamoun KremliAlMaarefa College

Bone and Joint Infection

Objectives

Understand the

Pathogenesis,

clinical picture, and

principles of management of

Acute osteomyelitisChronic osteomyelitisChronic specific osteomyelitis – TBAcute septic arthritis

Infection in Bone

Osteomyelitis (Bone and marrow infection):Osteo = bonemyel = bone marrowitis = inflammation

AcuteSub-acuteChronic

Specific (e,g. TB, Brucellosis, Fungal)Non specific (most common)

Route of Infection

Micro-organisms may reach the musculoskeletal tissues by:

Indirect spread via blood stream from a distant site The commonest Prick, injection, boil, distant wound

infection Nose, mouth, respiratory tract,

bowel, genitourinary tract

Direct spread from a contiguous focus of infection

Direct implantation from trauma or surgery

Slide Atlas of Orthop Radiology, A Greenspan. Gower Med Publ.

Factors and Types

Factors affecting type and severity:Type of invaderSite of infectionHost response

TypesPyogenic osteomyelitisSeptic arthritisChronic granulomatous reaction

Tuberculosis of bone or jointIndolent response to unusual organism

Fungal infection

Pathology

Infection: Multiplication and spread of pathogenic organisms within the body tissues

Inflammatory reaction: Acute / Subacute / Chronic Redness, heat, swelling, pain, loss of function

http://sphweb.bumc.bu.edu/

Pathology

Bone infection is different from soft-tissue infection:Bone consists of rigid compartmentsPressure is increased in acute inflammationMore vascular damage and cell death because of the

tight compartmentsIf not rapidly suppressed, will lead to necrosis

Principles of Treatment

1. Analgesia, rest, general supportive measures

2. Identify organism, use effective antibiotics or chemotherapy

3. Release pus as soon as it is detected, and remove avascular and necrotic tissue

4. Stabilize the bone if fractured

Acute pyogenic bone infection

Pathology:Formation of pus

a concentrate of defunct leucocytes, dead and dying bacteria and tissue debris

Localized in an abscess. Pressure builds up (tight space)Local spread

Through the cortexAlong adjacent tissue planesNearby joint

Distant spreadvia lymphatics

causing lymphangitis & lymphadenopathy

via the blood stream (bacteremia & septicemia)

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Principles of Treatment

Acute infections, if treated early with effective antibiotics, can usually be cured

Operative drainage needed once there is pus and bone necrosis

Acute haematogenous OM

Mostly children

Boys> girls

History of trauma often present? Micro-hematoma, ? insignificant

Acute OM - source of infection

Hematological (the commonest)

Infants:infected umbilical cord

Children:Boils, tonsillitis, skin abrasions, pricks, …

Adults:UTI, urinary catheter, indwelling arterial line, septic

tooth, dirty needle…

Acute OM - organisms

Gram +veStaphylococcus aureus (70%)Streptococcus pyogenesStreptococcus pneumoniae

Gram –veHaemophilus influenzae (50% < 4 y)Escherichia coliPseudomonas aeruginosaProteus mirabilisSalmonella species in patients

with sickle cell disease (why?)

http://pedemmorsels.com

http://pedemmorsels.com

Acute OM - children

Metaphysis of long bonesUpper tibia, proximal or distal femur?TraumaPeculiar arrangement of blood

vesselsTerminal arteries twist back in

hairpin loopsVascular stasisLowered oxygen tension

www.heightquest.com

http://cnx.org

Acute OM - children

Metaphysis of long bones

In infants, infection may reach Epiphysisanastomoses between metaphyseal and epiphyseal

blood vessels

www.heightquest.com

Acute OM - pathology

Inflammation: Intra-osseous pressure rises

Sever pain & obstruction of blood flow

SuppurationPus from day 2Sub-periosteal pus collection

Re-enters boneTo soft tissueTo joint

In infants In joints where metaphysis is partly intra-capsular

Hip, shoulder, elbow

www0.sun.ac.za

Acute OM - pathology

May spread to the joint causing Septic ArthritisIn infantsIn joints where

metaphysis is partly intra-capsularHip, shoulder, elbow

Essentials of Orthop Surgery,S Weisel, J Delahay. Saunders

Acute OM - pathology

Necrosis (7 days)Blood supply compromised by

raised pressure, stasis, thrombosis, periosteal stripping

Sequestrum formation (dead bone)

New bone formationSub-periosteal Involucrum formation

Resolution If infection controlled, &

pressure released

Clinical Features - Children

Severe pain

Malaise

Fever

Reluctant to move

Toxemia

History of previous source of infectionSore throat, skin infection, prick, injury

Clinical Features - Children

Localized pinpoint tenderness

Hotness

Local redness, swelling, edema (late signs)

Reduced range of motion

http://quizlet.com

Clinical Features - Infants

Constitutional symptoms may be mild

Failure to thrive, drowsy, irritable

Metaphyseal tenderness

Decreased ROM

Commonest around the knee

History of other infections (umbilical)

Clinical Features - Adults

Commonly thoracolumbar spine

Fever

Backache

History of UTI or urological procedure

Old ,diabetic, immune-compromised,

Diagnosis

History and clinical examination

WBC, ESR, CRP

X-ray (normal in the first (10-14) days

Ultrasound

Bone Scan Tc 99, Gallium 67

MRI

Aspiration

Acute OM - x-rays

First sign (10-14 days)Metaphyseal rarefactionPeriosteal reaction (new bone formation)

Apley,s System of Orthop & Fractures

Acute OM - x-rays

First sign (10-14 days)Metaphyseal rarefactionPeriosteal reaction (new bone formation)

LaterIncreasing ragged appearance (mottling)Sclerosis, rarefactionCavitationSequestrumInvolucrum: new bone formation

Acute OM - ultrasound

Detects sub-periosteal pus collection

Osteomyelitis. Mauricio Baptista

Acute OM - Bone scan

Increased activity – early

Osteomyelitis. Mauricio Baptista

Acute OM – MRI

Distinguish bet. bone & soft tissue infection

Perfect to detect early signs of infection – replacing bone scan

Osteomyelitis. Mauricio Baptista

Acute OM – other tests

WBC: leukocytosis, neutrophils

C-reactive protein: rises very early

ESR: raises several days

Blood culture

Aspiration from sub-periosteal collection or jointGood, even if no pusSmear for cells and bacteriaCulture / sensitivity

Differential Diagnosis

Cellulitis

Acute septic arthritis

Acute rheumatism

Sickle cell crisis