Risk of neurovascular injury with limited-open carpal tunnel release: Defining the safe-zone

Limited-open carpal tunnel release was performed in ten cadaver arms using the Safeguard system. The Safeguard guide was intentionally placed off of the longitudinal middle/ring finger axis, either in 15 degrees of radial deviation or 15 degrees of ulnar deviation. Despite the errant placement, carpal tunnel release was performed without damage to any neurovascular structure. The proximity of neurovascular structures to the middle/ring finger axis was measured in all ten cadaver specimens. From this, a safe-zone was defined for endoscopic or limited-open carpal tunnel release. The safe-zone expands when surgery is performed from distal to proximal. The area of the safe-zone is greatest when a protective guide is placed between the bursal sac of the carpal canal and the flexor retinaculum.