Fact-sheet: Septic arthritis
Updated on 02/07/2018 at 3:41 PM
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Definition
Intra-articular infection caused by a microorganism.
Diagnosis often delayed (risk of cartilage and/or bone destruction).
Routes of contamination:
- direct inoculation of the organism
- spread from an adjacent bone infection
- hematogenous origin (bacteremia).
Special case: infectious
sacroiliitis: infection of the sacroiliac joint.
Rare form of osteoarticular infection.
Often unilateral.
Organism: tuberculosis / brucellosis / pyogenic
Clinical features
Pain - redness - warmth.
Functional impairment.
Fever.
Soft tissue infiltration +/- collection
Laboratory findings
Inflammatory syndrome.
Positive blood cultures
Radiography
Signs of intra-articular effusion.
Cortical erosions / osteolysis.
Bone sequestrum in advanced forms
Ultrasound
Intra-articular effusion with capsular distension.
Synovitis (synovial thickening and hyperemia).
Ultrasound-guided aspiration
CT
Intra-articular collections with synovial enhancement.
Signs of osteitis (ill-defined cortical erosions, "wet sugar" osteolysis, bone sequestra).
Infiltration (cellulitis) or collection of adjacent soft tissues and muscular structures.
Special case:
Infectious sacroiliitis: Fat infiltration anterior to the sacroiliac joint space (early sign ++)
MRI
= Examination of choice.
Bone marrow edema = early sign.
Joint effusion + synovial enhancement.
Infiltration of periarticular soft tissues +/- abscess collections