Effects of endoscopic release of the transverse carpal ligament on carpal canal volume.

Ten hands in 10 patients with carpal tunnel syndrome were treated by subcutaneous transverse carpal ligament release using the Universal Subcutaneous Endoscope system. We analyzed the morphologic changes of the carpal canal with magnetic resonance imaging (0.064 T) before and after the operation. The axial plane, which includes the beak of the trapezium and the hook of the hamate, was selected for analysis. The soft tissue boundaries of the carpal canal were outlined at the plane. The cross-sectional area of the carpal canal was 232 +/- 49 mm2 before surgery and 320 +/- 108 mm2 after surgery. There was a 33% +/- 15% increase of the carpal canal cross-section after transverse carpal ligament release. The transverse carpal ligament became more outwardly convex after the operation. The endoscopic procedure is effective for increasing the cross-sectional area and volume of the carpal canal.