DISTANCE BETWEEN THE MEDIAN NERVE AND ULNAR NEUROVASCULAR BUNDLE - CLINICAL-SIGNIFICANCE WITH ULTRASONOGRAPHICALLY ASSISTED CARPAL-TUNNEL RELEASE

In ultrasonographically assisted carpel tunnel release, the zone of th e transverse carpal ligament between the median nerve and ulnar neurov ascular bundle is of significance because proximity of the cutting dev ice to these structures depends on its width. In this study, we measur ed the width of the zone at 5 levels in 60 wrists from 54 patients wit h surgery-indicated idiopathic carpal tunnel syndrome. The width of th e 5 levels ranged from 2.8 to 11.2 mm (mean, 7.1 mm) at the hook of th e hamate, 3.0 to 72.5 mm (mean, 7.9 mm) at the distal one fourth of th e carpal tunnel, 2.8 to 12.4 mm (mean, 8.0 mm) at the midsection of th e tunnel, 1.5 to 13.0 mm (mean, 7.4 mm) at the proximal one fourth of the tunnel, and 5.3 to 17.2 mm (mean, 10.2 mm) at the wrist crease. Th ese widths were not significantly col-related with radiographic measur ements of the hand (cord of the radiocarpal joint are, carpal height, third metacarpal, and hand length). We conclude that there is consider able variation of the width among individuals. Based on our clinical e xperience (3 wrists of 3 patients in this study), patients with a widt h of less than or equal to 3 mm at any level should be screened out pr eoperatively by wrist imaging. Our findings also may be of use to surg eons performing endoscopic carpal tunnel release. Copyright (C) 1998 b y the American Society for Surgery of the Hand.