Patent ID: 8734496

Claim:
An implant comprising: a joining member having a bone contact surface and an opposite upwardly facing surface and at least one opening with a groove formed around an inner circumference of the opening, said groove having an axially spaced upper and lower surface; a bone-anchor capable of being accommodated in the opening between said groove and said bone contacting surface; and an annular split-ring mounted in said groove, the annular split-ring sized to expand upon insertion of the anchor element into the opening and to come into direct contact with a head of the bone anchor to hold the bone anchor in the opening, said split-ring having an upper surface and a lower surface for respectively engaging said upper and lower surface of said groove, wherein the split-ring defines a distance between an inner and outer diameter of the annular split-ring, the outer diameter having a plurality of cutout portions so that the distance between the split-ring inner and outer diameters has alternating wider and narrower portions.