Radioscaphocapitate ligament

The radioscaphocapitate ligament is one of the intracapsular, extrinsic palmar radiocarpal ligaments and a volar stabilizer of the wrist ^1-3.

Gross anatomy

The radioscaphocapitate ligament connects the palmar surface of the distal radius with the scaphoid and the capitate bone, running in an oblique orientation and composes the radial and a part of the volar radiocarpal joint capsule ^1-4. It runs adjacent to the long radiolunate ligament, separated by the interligament sulcus. Together with the ulnocapitate ligament, it forms the palmar greater arc or arcuate ligament ^2,3.

Attachments

The proximal insertion or origin of the radioscaphocapitate ligament is located in the volar area from the radial styloid process to the middle of the scaphoid fossa ^1-3.

It covers and stabilizes the waist of the scaphoid bone like a sling and connects to the proximal surface of the distal pole. From there, fibres run to the palmar surface of the capitate bone, where they insert after blending with fibres from the ulnocapitate and scaphotriquetral and volar scaphotrapeziotrapezoid ligaments ^1-5.

Radiographic features

Ultrasound

The radioscaphocapitate ligament can be visualized on ultrasound with the transducer placed at the volar aspect of the radial side of the slightly extended wrist in the longitudinal plane and then rotated towards the capitate bone. The long axis of the ligament is displayed as a fibrillary structure attaching the distal radius to the scaphoid and capitate bone ^2,3.

MRI

The radioscaphocapitate ligament is easily seen on MRI. It can be best appreciated on coronal, sagittal or 3D images and usually shows a hypointense, striated appearance. The interligament sulcus, which separates the radioscaphocapitate ligament from medially adjacent and more proximally coursing long radiolunate ligament, can be delineated as a fluid intense structure.

Related pathology

The ligament is most likely injured or involved in the following pathologic conditions ^ref7,8:

• nondissociative carpal instability (CIND)
  • ulnar translocation (type 1): rheumatoid arthritis, Madelung deformity
  • radial translocation
  • radiocarpal translocation
• midcarpal instability (MCI)
  • dorsal midcarpal instability

See also

• wrist ligaments