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Ulnotriquetral ligament

The ulnotriquetral ligament (UTL) is a key component of the ulnocarpal complex, connecting the ulna to the triquetrum and contributing to the overall stability of the ulnocarpal joint. It forms part of the palmar (volar) portion of the triangular fibrocartilage complex (TFCC) and plays an important role in stabilizing the wrist during pronation, supination, and ulnar deviation.

The ligament functions in coordination with the ulnolunate and ulnocapitate ligaments, collectively referred to as the ulnocarpal meniscal homologue, which anchors the distal ulna to the carpal bones. Damage to the UTL is a common cause of ulnar-sided wrist pain, especially following trauma, degenerative TFCC tears, or repetitive strain injuries.

Synonyms

  • Volar ulnotriquetral ligament

  • Palmar ulnocarpal ligament (ulnotriquetral part)

  • Ulnocarpal ligament to triquetrum

Origin, Course, and Insertion

  • Origin: From the ulnar styloid process and adjacent ulnar fovea on the distal ulna.

  • Course: Extends distally and radially along the volar aspect of the wrist, deep to the flexor carpi ulnaris tendon.

  • Insertion: Attaches to the palmar surface of the triquetrum, and sometimes sends fibers to the lunate or articular disc margin.

Relations

  • Anteriorly: Flexor carpi ulnaris tendon and ulnar neurovascular bundle

  • Posteriorly: Triangular fibrocartilage and ulnar head

  • Laterally: Ulnolunate ligament

  • Medially: Ulnar collateral ligament of the wrist

  • Superiorly: Joint capsule of distal radioulnar joint

  • Inferiorly: Articular disc of the TFCC and triquetrum

Attachments

  • Proximal attachment: Ulnar styloid process and base of the TFCC articular disc

  • Distal attachment: Palmar surface of the triquetrum

  • Associated structures: Merges with fibers of the ulnolunate and ulnocapitate ligaments, forming a continuous volar ulnocarpal band

Function

  • Joint stability: Provides static stabilization to the ulnocarpal joint and supports the TFCC

  • Load transmission: Transfers compressive and shear forces from the carpus to the ulna during wrist motion

  • Movement control: Restrains excessive palmar translation of the triquetrum during ulnar deviation

  • Functional synergy: Works with ulnolunate ligament to maintain ulnocarpal congruity

Clinical Significance

  • TFCC injuries: The UTL is often involved in degenerative or traumatic TFCC tears

  • Ulnar wrist pain: Commonly associated with ligament attenuation or partial rupture

  • Ulnocarpal abutment syndrome: Chronic impaction between ulna and carpus stresses the UTL

  • Arthroscopic findings: Appears as a volar band continuous with the TFCC disc and ulnolunate ligament

  • Surgical relevance: Preservation critical during arthroscopic TFCC debridement or ulnar shortening osteotomy

  • Imaging relevance: MRI and CT arthrography are essential for assessing UTL continuity and TFCC integrity

MRI Appearance

  • T1-weighted images:

    • Ligament: low signal (dark) linear band connecting ulna to triquetrum

    • Surrounded by bright fat signal in adjacent soft tissue planes

    • Tear or degeneration: focal discontinuity or intermediate-signal thickening within the ligament

  • T2-weighted images:

    • Normal ligament: low signal (dark), sharply defined margins

    • Partial tear: linear or focal bright signal within ligament substance

    • Complete tear: discontinuity with adjacent joint effusion or fluid tracking along ligament path

    • Associated TFCC injury: increased signal in adjacent articular disc

  • STIR:

    • Normal: dark to intermediate low-signal band

    • Pathology: bright hyperintense signal indicating edema, strain, or partial tear

    • Detects subtle periligamentous inflammation or joint fluid accumulation

  • Proton Density Fat-Saturated (PD FS):

    • Normal ligament: dark linear structure

    • Tear or degeneration: bright signal foci or diffuse hyperintensity

    • Excellent for evaluating partial-thickness tears or early degeneration

  • T1 Fat-Sat Post-Contrast:

    • Normal: minimal or no enhancement

    • Inflamed or degenerative ligament: peripheral or diffuse enhancement

    • Postoperative scarring: enhances more uniformly than recurrent tear

MRI Arthrography Appearance

  • Direct MR arthrography: Contrast outlines the ligament and enters joint spaces.

  • Normal ligament: Appears as a continuous dark band with smooth margins; no contrast penetration.

  • Tear: Contrast extends into or beyond the ligament fibers, outlining a linear bright cleft between the ulna and triquetrum.

  • Degenerative changes: Mild irregularity, thickening, or focal enhancement of adjacent capsule.

  • TFCC involvement: Contrast leakage into the distal radioulnar joint or ulnocarpal recess may accompany complex tears.

CT Appearance

Non-Contrast CT:

  • Ligament: not directly visualized due to soft-tissue density

  • Bony landmarks (ulnar styloid and triquetrum) provide indirect reference points

  • Secondary signs: small avulsion fragments or periarticular sclerosis in chronic stress injuries

Post-Contrast CT (standard):

  • Mild enhancement of surrounding soft tissues or capsule if inflammation present

  • Used mainly for postoperative or degenerative evaluation

CT Arthrography Appearance

  • Normal ligament: Seen as a fine, continuous low-attenuation band bridging the ulna and triquetrum, without contrast penetration

  • Tear: Contrast enters or surrounds the ligament, forming a linear or irregular hyperdense cleft

  • Partial tear: Contrast partially tracks along the ligament margins

  • Complete tear: Full contrast communication between ulnocarpal and distal radioulnar joint spaces

  • Chronic degeneration: Irregular margins, thickened appearance, or subtle calcification near attachment sites

MRI images

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

MRI images

Ulnotriquetral ligament mri coronal image

MRI images

Ulnotriquetral ligament mri sag image