The carpal insertions of the transverse carpal ligament

To quantitatively define the anatomic insertions of the transverse carpal ligament (TCL) to the carpals.

We dissected 5 fresh-frozen cadaver limbs, isolating the TCL. The ligament insertion sites into bone were clearly marked and photographed. We then used computer software to measure the area of insertion into the individual carpals.

The TCL had consistent insertion sites into the scaphoid, trapezium, pisiform, and hamate. The average insertion of the TCL on the scaphoid was 6 × 6 mm (proximal to distal × radial to ulnar maximum distance), trapezium 13 × 6 mm, pisiform 9 × 6 mm, and hamate 11 × 5 mm. The area of ligament insertion on the scaphoid was 29 mm(2), trapezium was 42 mm(2), pisiform was 38 mm(2), and hamate was 40 mm(2). The perimeter of the ligament insertion on the scaphoid was 21 mm, trapezium was 28 mm, pisiform was 25 mm, and hamate was 29 mm.

The TCL has a broad but definable footprint on the trapezium and scaphoid on the radial side and the hamate and the pisiform on the ulnar side of the carpal tunnel. The distal carpal insertion sites are longer and oblong, whereas the proximal insertion sites are more circular.

Precise knowledge of TCL attachment sites may allow the surgeon greater confidence and safety during procedures that involve its release, such as carpal tunnel release, trapeziectomy, hook of hamate excision, or Guyon canal release.