Patent ID: 6887242

Claim:
In an anchoring assembly for insertion in skeletal bone, said anchoring assembly having a linking member having a threaded first end for engaging a securing nut and a tapered second end; a bone-engaging member having a first end adapted to engage said bone and a second end comprising a retention cavity constructed and arranged to engage said linking member second end, said retention cavity having a substantially-spherical exterior surface and a circular open mouth, the improvement comprising said retention cavity has a spherical inside wall, said wall narrowing toward said circular mouth; a bracing device in said retention cavity for universal movement within said retention cavity, said bracing device in the form of a split retention ring having a diameter greater than the diameter of said circular open mouth, said split retention ring mounted within said circular mouth of said retention cavity, said split retention ring comprising a main body having a tapered aperture therethrough and a gap, the tapered aperture being complementary to said taper of said linking member second end, thereby preventing removal of said linking member second end from within said retention cavity, and adapted to frictionally engage said linking member second end; whereby tightening of said securing nut draws said linking member second end against said split retention ring forcing said split retention ring along said narrowing spherical inside wall reducing said gap and applying progressive pressure on said linking member and selectively prevents relative motion between said linking member and said bone-engaging member.