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Dorsal ulnolunate ligament

The dorsal ulnolunate ligament (DULL) is a component of the ulnocarpal ligament complex located on the dorsal aspect of the wrist. It connects the ulna (through the triangular fibrocartilage complex, TFCC) to the lunate bone, providing dorsal stabilization between the distal ulna and the proximal carpal row.

This ligament helps coordinate motion between the ulna and lunate, restraining excessive dorsal translation and maintaining carpal stability during pronation-supination and ulnar deviation. It works synergistically with the dorsal radiocarpal and ulnotriquetral ligaments to stabilize the ulnocarpal joint.

Synonyms

  • Dorsal ulnocarpal ligament (ulnolunate part)

  • Dorsal band of the ulnocarpal complex

  • Dorsal ulnolunate component of TFCC

Origin, Course, and Insertion

  • Origin: From the dorsal radioulnar capsule and dorsal aspect of the triangular fibrocartilage complex (TFCC) near the base of the ulnar styloid process.

  • Course: Fibers run obliquely distolaterally across the dorsal ulnocarpal space toward the proximal carpal bones.

  • Insertion: Into the dorsal surface of the lunate, just proximal to its midpoint, where it blends with dorsal intercarpal fibers and the dorsal radiocarpal ligament.

Relations

  • Anteriorly: Lunate bone and proximal carpal joint capsule

  • Posteriorly: Extensor carpi ulnaris tendon and dorsal wrist capsule

  • Medially: Ulnotriquetral ligament and ulnar styloid process

  • Laterally: Dorsal radiocarpal ligament and dorsal lunocapitate fibers

  • Superiorly: Distal radioulnar joint capsule

  • Inferiorly: Dorsal surface of the lunate

Attachments

  • Proximal attachment: Dorsal radioulnar capsule and dorsal TFCC base

  • Distal attachment: Dorsal aspect of lunate bone

  • Associated structures: Blends with fibers of the dorsal ulnocarpal ligament complex and supports the dorsal capsule of the ulnocarpal joint

Function

  • Stabilization: Prevents excessive dorsal translation of the lunate and limits ulnocarpal shearing.

  • Joint coupling: Coordinates movement between the distal ulna and carpal bones during pronation-supination.

  • Tension control: Taut during wrist pronation and ulnar deviation.

  • Protection: Supports the dorsal TFCC and prevents lunate subluxation or instability.

Clinical Significance

  • Ligament tears: May occur with TFCC injuries, ulnar impaction syndrome, or dorsal wrist trauma.

  • Dorsal wrist pain: Common in overuse, falls, or twisting injuries.

  • Instability: Lunate instability or dorsal carpal subluxation can result from ligamentous insufficiency.

  • Degeneration: Chronic repetitive loading leads to thinning or fraying of the ligament fibers.

  • Surgical importance: Repair or reconstruction may be required in cases of TFCC complex disruption or lunate instability.

  • Imaging role: Critical in assessing TFCC integrity, dorsal carpal stability, and post-traumatic wrist disorders.

MRI Appearance

  • T1-weighted images:

    • Ligament: low signal (dark band) extending from dorsal ulna to lunate.

    • Adjacent fat and bone marrow: bright, providing contrast.

    • Disruption or tear: focal interruption or thickening with intermediate signal intensity.

    • Chronic degeneration: irregular, poorly defined margins and focal thinning.

  • T2-weighted images:

    • Normal ligament: low signal (dark line).

    • Partial tear or strain: focal bright signal within ligament fibers.

    • Complete tear: discontinuity with adjacent fluid hyperintensity in ulnocarpal recess.

    • Reactive synovitis or dorsal capsular edema: bright periligamentous signal.

  • STIR:

    • Normal ligament: dark or low signal.

    • Pathologic change: bright hyperintense signal due to edema, inflammation, or partial tear.

    • Highlights small fluid collections along the dorsal capsule.

  • Proton Density Fat-Saturated (PD FS):

    • Normal: dark linear structure with uniform thickness.

    • Partial tear: bright intraligamentous signal or focal thickening.

    • Complete rupture: fluid-filled defect separating the ligament margins.

  • T1 Fat-Sat Post-Contrast:

    • Normal: minimal enhancement.

    • Inflamed or reparative tissue: linear or diffuse enhancement along the ligament course.

    • Postoperative scar or synovitis: enhances strongly; chronic fibrosis remains low signal.

MRI Arthrography Appearance

  • The dorsal ulnolunate ligament forms part of the dorsal boundary of the ulnocarpal joint capsule.

  • Contrast leakage along the dorsal ulnocarpal recess indicates capsular or ligamentous disruption.

  • Partial tear: contrast tracks within the ligament substance but not completely through.

  • Complete tear: free passage of contrast between TFCC and lunate surface.

  • Chronic degeneration: irregular contrast outlines or attenuation of ligament contour.

CT Appearance

Non-Contrast CT:

  • Ligament not distinctly visualized (soft-tissue density).

  • Bony landmarks such as the ulnar styloid and dorsal lunate surface delineate ligament course indirectly.

  • May show calcifications or irregularity in chronic degeneration.

Post-Contrast CT (standard):

  • Capsule and adjacent soft tissues enhance mildly.

  • Inflamed or thickened ligament: appears as a soft-tissue density with periligamentous enhancement.

  • Chronic injury: fibrotic, non-enhancing bands or cortical irregularity at insertion sites.

CT Arthrography Appearance

  • Normal: Ligament appears as a thin, non-opacified dark band separating contrast-filled joint spaces.

  • Partial tear: Contrast partially enters the ligament substance or ulnolunate recess.

  • Complete tear: Contrast freely extends between the ulnocarpal joint and midcarpal space, outlining disrupted fibers.

  • Degenerative change: Irregular ligament contour, fraying, or discontinuous contrast margins.

  • Particularly useful when MRI is contraindicated, providing excellent visualization of the dorsal capsule and TFCC continuity.

MRI image

Dorsal ulnolunate ligament axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Dorsal ulnolunate ligament mri coronal

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Dorsal ulnolunate ligament mri sag image