The invention relates to an osteosynthesis device comprising a plate (10) and means for fixing a pin (20) that extends through the plate, in which the plate (10) includes a recess (12) for receiving the fixing means and the recess defines an inner edge (22), said fixing means comprising a ring (14) designed to receive the pin (20) and screwable locking means (32). According to the invention, the plate (10) has a threaded opening (26) on the edge of the recess (12), which opens into the inner edge (22), while the ring (14) is slit radially. The screwable locking means comprise a screw (32) that can be screwed through the threaded opening (26) so as to bear against the ring (14) and cause the ring (14) to bear with force against a portion of the inner edge (22) and tighten the ring (14) on the pin (20).Linvention concerne un dispositif dostéosynthèse comprenant une plaque (10) et des moyens de fixation dune broche (20) en travers de ladite plaque, ladite plaque (20) présentant un évidement (12) pour recevoir lesdits moyens de fixation, ledit évidement définissant un bord interne (22), lesdits moyens de fixation comprenant une couronne (14) destinée à recevoir ladite broche (20) et des moyens de blocage vissables (32) selon linvention ladite plaque (10) présente un orifice taraudé (26) en bordure dudit évidement (12) pour déboucher dans ledit bord interne (22), tandis que ladite couronne (14) est fendue radialement et lesdits moyens de blocage vissables comprennent une vis (32) vissable à travers ledit orifice taraudée (26) pour prendre appui contre ladite couronne (14) et provoquer lappui à force de ladite couronne (14) contre une portion dudit bord interne (22) et le resserrement de ladite couronne (14) sur ladite broche (20).
