Position Change of the Neurovascular Structures around the Carpal Tunnel with Dynamic Wrist Motion.
OBJECTIVE
The purpose of this study was to determine the anatomic relationships between neurovascular structures and the transverse carpal ligament so as to avoid complications during endoscopic carpal tunnel surgery.


METHODS
Twenty-eight patients (age range, 35-69 years) with carpal tunnel syndrome were entered into the study. We examined through wrist magnetic resonance imaging in three different positions (neutral, radial flexion, and ulnar flexion) and determined several anatomic landmark (distance from the hamate hook to the median nerve, ulnar nerve, and ulnar vessel) based on the lateral margin of the hook of the hamate. The median nerve and ulnar neurovascular structure were studied with the wrist in the neutral, ulnar, and radial flexion positions.


RESULTS
The ulnar neurovascular structures usually passed just over or ulnar to the hook of the hamate. However, in 12 hands, a looped ulnar artery coursed 0.6-3.3 mm radial to the hook of the hamate and continued to the superficial palmar arch. The looped ulnar artery migrates on the ulnar side of Guyon's canal (-5.2-1.8 mm radial to the hook of the hamate) with the wrist in radial flexion. During ulnar flexion of the wrist, the ulnar artery shifts more radially beyond the hook of the hamate (-2.5-5.7 mm).


CONCLUSIONS
It is appropriate to transect the ligament greater than 4 mm apart from the lateral margin of the hook of the hamate without placing the edge of the scalpel toward the ulnar side. We would also recommend not transecting the transverse carpal ligament in the ulnar flexed wrist position to protect the ulnar neurovascular structure.
Department of Neurosurgery, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
Jae Yoel
JY
Kwon
Ji Young
JY
Kim
Jae Taek
JT
Hong
Jae Hoon
JH
Sung
Byung Chul
BC
Son
Sang Won
SW
Lee