A method and set of instruments are disclosed particularly for carpal tunnel surgeries allowing a precision cut in the transverse carpal ligament (TCL) without direct vision or exposure of the ligament, except for its most proximal edge, but with guidance and safety of the cutting knife, eliminating or, at least, very much decreasing, the probability of cutting lines in the wrong direction and inadvertent (iatrogenic) lesions to the surrounding structures, comprising, in a preferred embodiment: a uniquely shaped cannulated guide rod, through which passes a flexible metal guide needle (33) which serves as a guideline for a uniquely shaped cutting knife or fasciotome (25) having a cannulated finger-like prong in the inferior edge of the blade portion of the knife plus, in a second embodiment of the invention, a sphere (32) coupled to the tip of the superior blunt finger-like prong present in the superior edge of said blade portion of said knife a uniquely shaped cutting knife or fasciotome with a curved shaft at 90° with, in a second embodiment of the invention, a pair of spheres coupled to the tip of two blunt finger- like prongs and an optional uniquely shaped slotted guide cannula (40) with a fenestration at its end tip allowing for the passage of the flexible metal guide needle (33) and, in a second embodiment of the invention, also a restraining metal arch or arch-brake (37) near its distal extremity and at its rear, two ears / handles for its proper handling.La présente invention concerne un procédé et une série dinstruments, utiles en particulier pour les chirurgies du canal carpien. Ledit procédé et ladite série dinstruments permettent une découpe de précision dans le ligament carpien transverse, sans vision ni exposition directe du ligament ‑ à lexception de son bord le plus proximal ‑, tout en guidant et en sécurisant la lame de découpe. Ils permettent ainsi déliminer, ou tout au moins de diminuer considérablement, la probabilité de découper des lignes dans
