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Capitohamate ligament

The capitohamate ligament is one of the intrinsic intercarpal ligaments of the wrist, connecting the capitate and hamate bones across their adjacent articular surfaces. It is a short, strong fibrous band that helps stabilize the capitohamate joint—a critical articulation in the distal carpal row—maintaining carpal alignment and contributing to the stability of the midcarpal joint complex.

The ligament consists of two distinct components: a palmar (volar) and a dorsal portion, both reinforcing the joint capsule. These components act together to limit excessive translation and rotation between the capitate and hamate bones, which is vital for coordinated wrist motion and load transfer.

Synonyms

  • Hamatocapitate ligament

  • Interosseous ligament of capitate and hamate

  • Capitohamate intercarpal ligament

Location and Structure

  • Position: Located in the distal carpal row, connecting the adjacent medial surfaces of the capitate and hamate bones.

  • Type: Intrinsic interosseous ligament, composed of dense collagenous connective tissue.

  • Extent: Lies between the capitate head and hamate body, crossing the midcarpal joint.

  • Divisions: Consists of dorsal and palmar (volar) bands blending with the joint capsule.

Dorsal Capitohamate Ligament

  • Location: Runs across the dorsal surfaces of the capitate and hamate.

  • Orientation: Fibers extend obliquely from the dorsolateral aspect of the capitate to the dorsomedial surface of the hamate.

  • Structure: Thin but strong fibrous band integrated with the dorsal carpal capsule.

  • Function: Reinforces the dorsal midcarpal joint, resists excessive palmar flexion, and contributes to stability during wrist extension.

  • Relations:

    • Superficial: Extensor carpi ulnaris and extensor digitorum tendons

    • Deep: Dorsal joint capsule and dorsal aspects of capitate and hamate

Palmar (Volar) Capitohamate Ligament

  • Location: Spans between the palmar surfaces of the capitate and hamate.

  • Orientation: Fibers pass obliquely and slightly distally, continuous with the palmar midcarpal ligamentous complex.

  • Structure: Broader and stronger than the dorsal component; blends with the palmar intercarpal ligament and the sheath of the flexor tendons.

  • Function: Provides stability during dorsiflexion, limits dorsal translation, and supports the carpal arch.

  • Relations:

    • Superficial: Flexor tendons within the carpal tunnel and flexor retinaculum

    • Deep: Palmar aspect of capitate and hamate, articular capsule

Attachments

  • Proximal attachment: Medial surface of the capitate bone

  • Distal attachment: Lateral surface of the hamate bone

  • Continuity: Merges proximally with intercarpal capsular fibers and distally with adjacent interosseous ligaments (capitolunate and triquetrohamate)

Function

  • Joint stabilization: Maintains articulation between the capitate and hamate in the distal carpal row

  • Force distribution: Aids in transmitting axial loads from the metacarpals to the proximal carpal row

  • Motion limitation: Restricts abnormal translation and torsion during wrist movement

  • Kinematic coordination: Contributes to synchronous motion of the distal carpal row during flexion-extension and ulnar deviation

Clinical Significance

  • Injury or tear: Can occur with carpal trauma, hyperextension, or repetitive loading

  • Carpal instability: Ligamentous laxity or rupture may cause midcarpal instability and pain at the ulnar side of the wrist

  • Degeneration: Chronic stress or osteoarthritis may weaken the ligament and capsule

  • Surgical importance: Must be preserved during carpal fusion, wrist arthroscopy, or ligament reconstruction procedures

  • Imaging role: Evaluated in wrist instability, arthritis, trauma, and post-surgical follow-up

MRI Appearance

  • T1-weighted images:

    • Ligament: low signal (dark) linear band between the capitate and hamate

    • Adjacent bone marrow: bright due to fatty content

    • Cartilage: thin intermediate signal layer at articular surfaces

    • Tears or degeneration: focal disruption or irregular hyperintensity within the ligament

  • T2-weighted images:

    • Normal ligament: low signal, sharply defined

    • Adjacent joint fluid: bright, highlighting ligament margins

    • Partial tears: focal bright hyperintense areas or fiber discontinuity

    • Complete rupture: absence or retraction of ligament with bright intervening joint fluid

  • STIR:

    • Normal ligament: dark to intermediate signal

    • Injury or inflammation: bright hyperintensity in periligamentous soft tissues or marrow edema of capitate/hamate

  • Proton Density Fat-Saturated (PD FS):

    • Ligament: low to intermediate signal

    • Pathology: bright hyperintense zones within or adjacent to ligament (edema, sprain, or partial tear)

    • Excellent for evaluating subtle intercarpal ligament injuries

  • T1 Fat-Sat Post-Contrast:

    • Normal: minimal enhancement of ligament margins

    • Pathology: periligamentous enhancement in inflammation or capsulitis; enhancing fluid may outline torn fibers

MRI Arthrography Appearance

  • Normal: Contrast remains confined to the capitohamate joint space; ligament appears as a thin, intact low-signal band.

  • Partial tear: Small contrast extension or irregularity along one surface of the ligament.

  • Complete tear: Contrast leakage between capitate and hamate bones into adjacent midcarpal compartments, confirming disruption.

  • Utility: Provides clear visualization of intra-articular ligament integrity and subtle fiber defects.

CT Appearance

Non-Contrast CT:

  • Ligament not directly visible, but the bony margins of capitate and hamate are well defined.

  • Joint space: uniform, with smooth cortical margins.

  • Pathology: small osseous avulsions, fractures, or degenerative subchondral cysts suggest ligament injury.

Post-Contrast CT (standard):

  • Ligamentous detail limited; contrast highlights surrounding capsular or synovial thickening.

  • May show enhancing soft tissue density at ligament site in inflammation.

CT Arthrography Appearance

  • Normal: Contrast outlines the capitohamate joint clearly; ligament appears as a non-opacified linear structure between articular surfaces.

  • Partial tear: Contrast insinuates along one border of the ligament without full communication.

  • Complete tear: Free passage of contrast between capitohamate and adjacent midcarpal joints, confirming disruption.

  • Degenerative change: Irregular joint space contour or small contrast-filled recesses adjacent to ligament attachment sites.

MRI images

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

MRI images

Capitohamate ligament axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI images

Capitohamate ligament coronal mri image