The Safety of Entrance Reference Line in Endoscopic Carpal Tunnel Release: A Cadaveric Anatomical Evaluation

ABSTRACT

OBJECTIVE: The purpose of this study is to investigate the anatomic relationship between the neurovasular structures and transverse carpal ligment(TCL) to avoid complications during endoscopic carpal tunnel release. METHODS: Sixteen fresh cadaver hands from 3 men and 5 women(age range, 58~74 years) were used. Neurovascular structures around the TCL were meticulously dissected under a loupe magnification and several morphometric indices were calculated. RESULTS: We found an average length of TCL is 41mm and average distance between the TCL distal margin and superficial palmar arch along the flexor tendon of the ring finger is 9.2mm. In 3 hands, the looped ulnar artery, coursed 1 to 4mm radial to hook of hamate, continuing to the superficial palmar arch. During radial-to-ulnar flexion of the wrist, the looped ulnar artery beyond the hook of hamate shifts more radially (2 to 7mm) with proximal carpal bone. We also noted a Berretini branch located adjacent to the edge of the distal TCL. CONCLUSION: It is appropriate to transect the ligament at least 4mm radial from the radial margin of the hook of hamate or transect the proximal ligament in the radially deviated hand position to protect ulnar neurovascular structure. The proximal portal could be made just ulnar to the palmaris longus tendon to avoid the vascular injury in the proximal portion of the TCL.