Is complete release of all volar carpal canal structures necessary for complete decompression in endoscopic carpal tunnel release?

This study investigated the need to completely divide the flexor retinaculum to achieve full decompression of the median nerve in the carpal canal, using carpal canal pressure measurements at the mid-point and/or the proximal one-third of the flexor retinaculum to analyse the degree of decompression after release of successive lengths of the flexor retinaculum from the distal holdfast fibres to its proximal margin. Pressure measurements were taken at each operative step in the resting hand position and during active power gripping. The pressure measurements indicated that decompression of the carpal canal was achieved both at rest and on active gripping after complete division of the flexor retinaculum. However, pressure measurements indicated that complete decompression had not been achieved during active power gripping with the proximal one-third of the flexor retinaculum intact. These results demonstrate the need for complete release of the full length of the flexor retinaculum, including the distal holdfast fibres.