Patent ID: 8092502

Claim:
A polyaxial bone screw assembly comprising: a) an elongate shank having a body with a longitudinal axis for fixation to a bone, and a capture structure having a first radiused surface, a first helically wound guide and advancement structure with a major diameter and an axial projection extending upwardly above the capture structure, the axial projection including a top surface with a second radiused surface different from that of the first radiused surface; and b) a head having an inner cavity and a second helically wound guide and advancement structure defining a capture structure loading aperture positioned at a bottom end of the head, the aperture having a diameter and communicating with the cavity, the first helically wound guide and advancement structure being mateable with the second helically wound guide and advancement structure to provide for rotatable uploading of the capture structure through the aperture into the cavity, the major diameter of the first helically wound guide and advancement structure being larger than the loading aperture diameter, the capture structure being swivelably received in the cavity during positioning of the shank relative to the head and being urged into frictional engagement with the head in a locked configuration.