Device for immobilishing an osteosynthesis pin in a bone part

Device for immobilizing with respect to a fixed element a threaded support pin screwed in a bone part along an axis, comprising a threaded locking sleeve which is connectable by screwing of the fixed element, which is provided with an axial bore which receives the pin, the axis of the threading of this sleeve is offset in relation to the axis of the pin when the pin is in place on the bone part, and/or the axis of the bore of the locking sleeve is offset in relation to the axis of the threading, wherein the fixed element is constituted by a support receiving intermediate pieces which are mounted dispacably and rotationally along a profile of the support, fixing means ensuring the immobilisation of the intermediate pieces with respect to the fixed element, and wherein said support is constituted by a rail of which an internal profile is of hemispherical shape and whose base is pierced with a longitudinal slot adapted to be traversed by the threaded pins,

• the intermediate pieces are constituted by spheres adapted to be positioned at any point of the rail,
• it comprises an upper cover of hemispherical internal profile of which the apex is pierced with a longitudinal slot adapted to be traversed by the threaded pins (21),
• it comprises tightening means adapted to apply the spherical intermediate pieces against the rail in order to immobilise them both in translation and in rotation with respect thereto.