Hemarthrosis and Lipohemarthrosis

Hemarthrosis and Lipohemarthrosis

KEY FACTS

Terminology

• Hemarthrosis: Blood in joint cavity
• Lipohemarthrosis: Blood and fat in joint cavity

Imaging

• Layered joint effusion
• Hemarthrosis initially seen as finely speckled echogenic joint fluid

After ~ 5 minutes, may become 2-layered joint effusion

Superficial hypoechoic layer represents supernatant serum

Deep hyperechoic layer represents dependent red blood cells (RBCs)
• Lipohemarthrosis initially seen as finely speckled echogenic joint fluid

After ~ 10 minutes, may become 3-layered joint effusion

Superficial hyperechoic layer represents floating fat

Central hypoechoic layer represents supernatant serum

Deep hyperechoic layer represents dependent RBCs

± hypoechoic areas within floating fat due to trapped blood
• Hemophilia early arthropathy detection with US score (HEAD-US)
• Targeted examination of elbow, knee, ankle
• Synovial hypertrophy graded as 0 (absent/minimal), 1 (mild/moderate), or 2 (severe) synovial proliferation
• Subchondral bone graded as 0 (normal), 1 (mild), or 2 (moderate/severe) subchondral bone irregularity ± osteophytes
• Cartilage thinning graded as 0 (normal), 1 (mild), 2 (moderate), 3 (severe), or 4 (complete) thinning

Top Differential Diagnoses

• Septic arthritis
• Gout
• Inflammatory synovitis

Diagnostic Checklist

• Lipohemarthrosis is marker of articular surface fracture

TERMINOLOGY

Synonyms

• Posttraumatic hemarthrosis or lipohemarthrosis
• Spontaneous hemarthrosis
• Hemophiliac arthropathy

Definitions

• Hemarthrosis: Blood in joint cavity
• Lipohemarthrosis: Blood and fat in joint cavity

Very specific for intraarticular fracture
• Spontaneous hemarthrosis: Hemarthrosis developing in absence of predisposing trauma, synovial tumor, or hemophilia
• Hemophiliac arthropathy: Arthropathy secondary to repeated hemarthrosis due to inherited clotting disorder

IMAGING

General Features

• Best diagnostic clue

Layered joint effusion
• Location

Knee > ankle > elbow > shoulder > hip

Radiographic Findings

• Hyperdense joint effusion

Density of hemorrhage > simple synovial fluid
• Horizontal beam radiography for lipohemarthrosis: Fat-fluid level due to attenuation differences in fat and blood components

Fat is less dense and floats on blood surface

Lipohemarthrosis is present in 35% of knee intraarticular fractures

– High specificity but low sensitivity for intraarticular fractures

CT Findings

• NECT

Hemarthrosis: 2 distinct layers

– Superficial isodense layer [~ 30 Hounsfield units (HU)] = serum

– Deep hyperdense layer (~ 70 HU) = red blood cells (RBCs)

Lipohemarthrosis: 3 distinct layers

– Superficial hypodense layer (~ -70 HU) = fat

– Central intermediate layer (~ 20 HU) = serum

– Deep hyperdense layer (~ 90 HU) = RBCs

MR Findings

• T2WI

Hemarthrosis: 2 distinct signal bands

– Superficial hyperintense band = serum

– Deep isodense band = dependent RBCs

Lipohemarthrosis: 3 distinct signal bands

– Superficial hyperintense band = floating fat

– Central hyperintense band = serum

– Deep isodense band = dependent RBCs

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Tags: Diagnostic Ultrasound Musculoskeletal

Apr 9, 2020 | Posted by admin in MUSCULOSKELETAL IMAGING | Comments Off

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