Patent ID: 8906068

Claim:
A spinal fixation system for use in the fixation of a spine comprising: (i) a coupling element having a generally cylindrical wall and a pair of opposed longitudinal apertures through the wall and extending from a top end of the coupling element to an aperture bottom in spaced relation from a bottom end of the coupling element, the generally cylindrical wall defining an interior space of the coupling element dimensioned for admitting a bone fixation element thereinto, the apertures dimensioned for admitting a fixation rod diametrically through the interior space of the coupling element; and a hole through the bottom end of the coupling element dimensioned for admitting a shank of the elongated bone fixation element therethrough, the hole being smaller than a head of the bone fixation element for retaining the head within the interior space of the coupling element, the shank of the bone fixation element extending downwardly from the head of the bone fixation element, the bone fixation element head having a first portion of a first size and a second portion of a second size which is greater than the first size of the first portion, threads on exterior surfaces of the first portion being in contact with the bottom portion of the retaining element; (ii) a securing element having a generally cylindrical body configured to fit within the coupling element, a biasing member located on a lower portion of the securing element; and a substantially concave surface dimensioned for at least partially circumscribing a fixation rod; and (iii) a retaining element having: a substantially concave top surface dimensioned for at least partially circumscribing a fixation rod; an outwardly extending wing; a crimping portion, wherein the crimping portion at least partially compresses when a force is exerted on the retaining element; and a substantially concave bottom surface dimensioned for at least partially circumscribing a head of a bone fixation element, wherein: the substantially concave top surface of the retaining element has a contact area, wherein the contact area is a linear increasing slope extending from a base section toward the wing and wherein the configuration of the contact area does not match the outer surface contour of the fixation rod.