Surgical assembly, and bone anchor screw and device for extending one such screw that belong to said surgical assembly

摘要

The surgical assembly includes: a bone anchorage screw having an anchorage portion for anchoring in a vertebral column, and a head in the form of a socket; and an extension device adapted to fit over the socket of the bone anchorage screw for forming a longitudinal extension thereto. The extension device includes a first tubular element referred to as an “inner tube”, of inside diameter greater than or equal to the inside diameter of the socket of the bone anchorage screw, and extended longitudinally by two diametrically opposite branches, forming jaws for clamping onto the outside surface of the socket so as to lock onto the socket, and a second tubular element referred to as an “outer tube”, mounted to slide along said inner tube. The outer tube is extended longitudinally by two diametrically opposite branches having their free ends in register with the free ends of the two branches of the inner tube, and being provided with retaining means for co-operating with complementary retaining means arranged on the socket to prevent the branches from moving apart from each.