Medical fastener (10), comprising: an elongated shaft (13) having a proximal end (6) and a distal end (4), a first thread (12) helically wound around said tree (13), said first having thread (12) facets defining surfaces as upper (21) and lower (22) flanks, said upper (21) and lower (22) flanks oriented in a substantially parallel relationship, a second thread (24) helically wound around said tree ( 13), characterized in that said second thread (24) has facets (27, 28) oriented substantially diametrically opposite to said first thread facets (21, 22), and that the fastener further comprises a self-tapping cutter (200) at said distal end said cutter having a claw-shaped cutting element claw with a sharp leading edge (53), a blunt rear edge (51) and a channel (55) that operatively communicates with it to receive bone fragments therein, where said second thread facets (27, 28) are substantially parallel to each other, and said first thread (12) has a crest diameter greater than said second thread crest diameter, and where the thread facets (21, 22) of the first thread (12) and the thread facets (27, 28) of the second thread (24) are oriented at right angles to the longitudinal axis (100) of the fastener, where the fastener is adapted to form a bone profile that it appears in the longitudinal section as a series of serrated battlements of square saw.Sujetador (10) médico, que comprende: un árbol (13) alargado que tiene un extremo (6) próximo y un extremo (4) distal, una primera rosca (12) helicoidalmente enrollada alrededor de dicho árbol (13), teniendo dicha primer rosca (12) facetas definiendo superficies como flancos superiores (21) e inferior (22), dichos flancos superior (21) e inferior (22) orientados en una relación sustancialmente paralela, una segunda rosca (24) enrollada helicoidalmente alrededor de dicho árbol (13), caracterizado porque dicha segunda rosca (24) tiene facetas (27, 28) orientadas sustancialmente diametralmente opuesta a dichas primeras facetas
