Patent ID: 7641674

Claim:
An anchor assembly for engaging a connecting element along the spinal column, comprising: an anchor member engageable to a vertebral body; a receiver at a proximal end of said anchor member, said receiver defining a passage for receiving the connecting element therethrough and an internal thread profile extending from said passage; and an engaging member threadingly engageable with said internal thread profile, wherein said engaging member includes a rotational center and an end surface having a plurality of elongated, arcuate projecting members extending therefrom about said rotational center, said projecting members being structured to deform an outer surface of said connecting element when said engaging member is threadingly engaged to said internal thread profile of said receiver with said projecting members in contact with the connecting element, wherein a first one of said projecting members extends partially about said rotational center on a first side of said rotational center along an arc having a first radius from said rotational center of said engaging member and a second one of said projecting members extends partially about said rotational center on a second side of said rotational center along an arc having a second radius from said rotational center of said engaging member and opposite said first side and in substantially non-overlapping relation with said first projecting member with a part of said first projecting member overlapping with a part of said second projecting member, wherein said first projecting member includes a first height extending from said end surface and said second projecting member includes a second height extending from said end surface, said first height being greater than said second height and said first radius being greater than said second radius, wherein said first projecting member and said second projecting member each include a leading end wall formed by a sloped surface extending from said end surface to an outer end of said respective projecting member with said leading end wall of at least one of said first and second projecting members forming a cutting edge to facilitate entry of said at least one of said first and second projecting members into the connecting element as said engaging member is threadingly engaged to said internal thread profile of said receiver and said outer end is continuous and arcuate from said leading end wall along a length of said at least one of said first and second projecting members.