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Dorsal radial tubercle (Lister’s tubercle)

The dorsal radial tubercle, commonly known as Lister’s tubercle, is a prominent bony ridge located on the dorsal surface of the distal radius, approximately midway between the radial and ulnar styloid processes. It acts as a pulley for the extensor pollicis longus (EPL) tendon, redirecting its course toward the thumb, and serves as a crucial surface landmark in wrist anatomy and surgical approaches.

This tubercle is palpable beneath the skin on the dorsal wrist and lies posterior to the distal radioulnar joint and proximal to the radial styloid. It divides the dorsal wrist extensor tendons into medial and lateral compartments, providing orientation during tendon and fracture surgery.

Synonyms

  • Lister’s tubercle

  • Dorsal tubercle of radius

  • Radial dorsal prominence

Location and Structure

  • Situated on the dorsal aspect of the distal radius, near the junction of its middle and lateral thirds.

  • The tubercle projects dorsally as a small bony ridge or prominence that varies in size and contour among individuals.

  • Forms part of the distal radial dorsal surface, covered by periosteum and closely related to the overlying extensor retinaculum and tendons.

  • Functions as an osseous pulley for the extensor pollicis longus tendon, altering its direction of pull toward the thumb.

Relations

  • Anteriorly: Distal radius metaphysis and radiocarpal joint

  • Posteriorly: Skin, subcutaneous tissue, and extensor retinaculum

  • Medially: Extensor pollicis longus tendon (passes around it)

  • Laterally: Extensor carpi radialis longus and brevis tendons

  • Inferiorly: Articular surface of distal radius articulating with the scaphoid and lunate

Attachments

  • Periosteum and retinacular fibers adhere over its surface.

  • The extensor retinaculum anchors adjacent to the tubercle, forming a pulley mechanism for the EPL tendon.

  • Occasionally, the radiate carpal ligaments and thin fibrous septa of the dorsal compartments attach partially to its borders.

Function

  • Pulley mechanism: Acts as a fixed bony fulcrum for the extensor pollicis longus tendon, changing its direction laterally toward the thumb.

  • Mechanical advantage: Enhances extension and abduction efficiency of the thumb at the interphalangeal and carpometacarpal joints.

  • Landmark utility: Serves as a key surgical and radiologic landmark for identifying dorsal compartments and evaluating distal radius fractures.

  • Separation of compartments: Divides the dorsal extensor tendons into medial (EPL, EDC, EDM) and lateral (ECRL, ECRB, APL, EPB) groups.

Clinical Significance

  • Lister’s tubercle fracture: May accompany distal radius fractures; displacement can cause EPL tendon irritation or rupture.

  • Tendinopathy: Friction between EPL tendon and tubercle can result in chronic tenosynovitis or attritional tear.

  • Post-surgical landmark: Used during open reduction internal fixation (ORIF) of distal radius fractures to locate dorsal compartments.

  • Variation: Prominence or accessory ossicle (Listersian tubercle variant) may mimic osteophyte or foreign body on imaging.

  • EPL rupture: Commonly occurs due to ischemia or mechanical attrition over a prominent or roughened tubercle, especially after fracture healing.

MRI Appearance

  • T1-weighted images:

    • Cortex: Low signal (dark), sharply marginated.

    • Marrow: Bright signal from fatty content within cancellous bone.

    • Overlying tendons: Low-signal linear bands (EPL passing medially and posteriorly).

    • Peritubercular fat: Bright, outlining the bony contour.

    • Fracture or edema: Focal low-signal line with surrounding intermediate signal.

  • T2-weighted images:

    • Cortex: Low signal.

    • Marrow: Bright, slightly less intense than T1.

    • Adjacent soft tissues: Intermediate-to-bright signal.

    • EPL tendon pathology: Bright hyperintensity around or within tendon sheath indicating tenosynovitis or partial tear.

    • Fracture or bone bruise: Linear low-signal defect with surrounding hyperintense marrow edema.

  • STIR:

    • Normal bone: Intermediate-to-dark signal.

    • Marrow edema or fracture: Bright hyperintensity with indistinct trabecular margins.

    • Soft tissue inflammation: Increased peritendinous signal around EPL tendon.

  • Proton Density Fat-Saturated (PD FS):

    • Normal bone: Intermediate-to-dark signal, smooth cortex.

    • EPL tenosynovitis or irritation: Bright peritendinous hyperintensity.

    • Fracture line or contusion: Focal bright signal in subcortical region.

    • Excellent for evaluating tendon sheath pathology and subtle bone marrow changes.

  • T1 Fat-Sat Post-Contrast:

    • Normal bone: Mild uniform enhancement.

    • Inflammatory lesions: Periosteal or tendon sheath enhancement.

    • EPL tendinitis: Enhancing peritendinous tissue with mild fluid accumulation.

    • Post-fracture granulation: Linear enhancement at cortical margins or callus region.

CT Appearance

Non-Contrast CT:

  • Cortex: High attenuation, dense and well-defined.

  • Marrow: Intermediate attenuation with visible trabecular pattern.

  • Morphology: Bony ridge posteriorly projecting from distal radius, easily visualized in sagittal and axial planes.

  • Pathology:

    • Fracture: cortical break or step-off along dorsal radius.

    • Prominent or hypertrophic tubercle: may indent or compress EPL tendon groove.

    • Osteophyte formation or accessory ossicle clearly delineated.

CT VRT 3D image

Dorsal radial tubercle (Lister’s tubercle) CT 3D VRT image -img-00000-00000

MRI image

Dorsal radial tubercle (Lister’s tubercle) axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Dorsal radial tubercle (Lister’s tubercle) sag cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

CT image

Dorsal radial tubercle (Lister’s tubercle) ct sagittal image