The Carpal Insertions of the Transverse Carpal Ligament

PurposeTo quantitatively define the anatomic insertions of the transverse carpal ligament (TCL) to the carpals.MethodsWe 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.ResultsThe 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 mm2, trapezium was 42 mm2, pisiform was 38 mm2, and hamate was 40 mm2. 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.ConclusionsThe 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.Clinical relevancePrecise 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.