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Dorsal trapeziotrapezoid ligament

The dorsal trapeziotrapezoid ligament (DTTL) is one of the key intrinsic intercarpal ligaments that stabilizes the articulation between the trapezium and trapezoid bones in the distal carpal row. It reinforces the dorsal aspect of the trapeziotrapezoid joint capsule and plays a vital role in maintaining the integrity of the radial carpal column, especially during wrist motion and load transmission.

It works in conjunction with the palmar trapeziotrapezoid ligament (PTTL) on the volar surface, forming a paired stabilizing complex that secures the trapezium–trapezoid articulation and supports the carpometacarpal (CMC) joint of the thumb.

Synonyms

  • Dorsal trapezium–trapezoid ligament

  • Dorsal trapeziotrapezoid intercarpal ligament

  • Palmar trapeziotrapezoid ligament (volar counterpart)

Location and Structure

  • The trapeziotrapezoid joint lies between the trapezium (laterally) and trapezoid (medially) in the distal carpal row.

  • The DTTL spans the dorsal surfaces of these two bones, forming a short, oblique, and robust fibrous band.

  • The PTTL runs across the palmar aspect, forming a thinner but important stabilizing layer that blends with the joint capsule.

  • Both ligaments are part of the intrinsic intercarpal ligament complex, directly connecting adjacent carpal bones.

Attachments

  • Proximal attachment (Dorsal): Dorsal ridge of the trapezium

  • Distal attachment (Dorsal): Dorsal ridge of the trapezoid

  • Proximal attachment (Palmar): Volar surface of the trapezium, near the scaphotrapezial joint

  • Distal attachment (Palmar): Volar surface of the trapezoid, blending with the anterior capsule of the trapeziotrapezoid joint

Relations

  • Dorsally: Extensor carpi radialis longus and brevis tendons cross superficially

  • Palmarly: Flexor carpi radialis tendon and the palmar fascia of the wrist

  • Laterally: Trapezium bone and base of the first metacarpal (thumb)

  • Medially: Trapezoid bone and base of the second metacarpal

  • Deep: Articular capsule of the trapeziotrapezoid joint

  • Superficial: Dorsal intercarpal fascia and overlying extensor retinaculum

Function

  • Joint stabilization: Maintains alignment between the trapezium and trapezoid, preventing excessive shear or rotation

  • Load distribution: Helps distribute forces across the radial column of the wrist during grip and thumb movement

  • Kinematic control: Restrains abnormal translation or separation at the trapeziotrapezoid joint

  • Dynamic support: Assists in stabilizing the base of the thumb (first CMC joint) during opposition and grasping

Clinical Significance

  • Sprains or partial tears: Common in repetitive wrist loading (athletes, manual laborers)

  • Degeneration: May occur in conjunction with scaphotrapeziotrapezoid (STT) arthritis

  • Instability: Disruption may contribute to radial column instability and basal thumb pain

  • Post-traumatic changes: May follow wrist fractures, especially trapezium or trapezoid fractures

  • Surgical relevance: Important landmark during trapeziectomy, ligament reconstruction, and wrist arthrodesis

MRI Appearance

  • T1-weighted images:

    • Ligament appears as a thin, low-signal (dark) linear band between the trapezium and trapezoid.

    • Surrounded by bright fat, allowing clear visualization.

    • Chronic scarring or thickening may show intermediate signal intensity.

  • T2-weighted images:

    • Normal ligament: low signal (dark band) against intermediate joint fluid background.

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

    • Complete tear: full-thickness defect with joint fluid interposition between bone margins.

    • Associated degenerative changes: irregular articular cartilage or subchondral cysts.

  • STIR:

    • Normal ligament: intermediate-to-dark signal.

    • Injury: bright hyperintense signal within or around ligament (edema, strain, or capsular inflammation).

    • Highlights subtle periligamentous edema.

  • Proton Density Fat-Saturated (PD FS):

    • Normal: low-signal linear structure with sharp borders.

    • Partial tears: focal bright signal or fiber irregularity.

    • Surrounding synovitis: mild periligamentous hyperintensity.

  • T1 Fat-Sat Post-Contrast:

    • Normal ligament: minimal enhancement.

    • Inflammation: mild linear or periligamentous enhancement.

    • Chronic degeneration: heterogeneous or patchy enhancement due to granulation tissue.

CT Appearance

Non-Contrast CT:

  • Ligament not directly visualized; appears as a thin low-density line between trapezium and trapezoid.

  • Bony margins are smooth and sharply defined in normal anatomy.

  • Degeneration: joint space narrowing, sclerosis, subchondral cysts, or marginal osteophytes.

  • Helpful for assessing associated carpal bone fractures or osteoarthritic changes.

Post-Contrast CT (standard):

  • Enhancing periligamentous soft tissues may indicate inflammation or fibrosis.

  • Distinguishes ligamentous injury from surrounding fat and capsule.

CT Arthrography Appearance

  • Normal:

    • Ligament appears as a thin low-density structure between trapezium and trapezoid, with contrast confined to joint recesses.

    • Joint capsule remains intact with smooth articular margins.

  • Partial tear:

    • Focal leakage of contrast into periligamentous tissues or interstitial gaps.

    • Slight irregularity or thinning of the ligament contour.

  • Complete tear:

    • Free communication of contrast between the trapeziotrapezoid and adjacent STT joint spaces.

    • Contrast extends into the interosseous region, confirming capsuloligamentous disruption.

  • Degenerative changes:

    • Contrast outlines irregular articular surfaces, joint space narrowing, and small subchondral cysts.

Palmar (Volar) Trapeziotrapezoid Ligament

  • Location: Spans the volar surfaces of the trapezium and trapezoid, forming part of the palmar intercarpal ligament complex.

  • Appearance: Thinner and flatter than its dorsal counterpart; blends with the palmar joint capsule.

  • Function: Resists hyperextension and contributes to volar carpal stability.

  • MRI/CT Appearance: Similar to dorsal ligament—low-signal band on MRI, thin low-density line on CT. Injury or strain appears as focal hyperintensity or periligamentous edema.

MRI image

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