Polyaxial bone screw with helically wound capture connection

In a polyaxial bone screw assembly for surgical implantation and including a shank and a head, the shank having a capture end and an elongate threaded body having an axis of rotation for being driven by rotation into a bone, the head having an outward opening channel adapted to receive a rod within the channel, the head further having an inner cavity and a shank receiving opening, the improvement comprising:

• (a) a capture structure disposed on the shank capture end sized and configured to be receivable through the shank receiving opening, the capture structure having a projection with a tool engagement structure, an upper engagement surface, and a stopping surface;
• (b) a retainer structure, having a cavity defined by a lower chamber, the lower chamber having a protrusion surface that is configured to mate with the stopping surface and the cavity configured to mate with the capture structure within the head cavity so as to polyaxially rotate with the capture structure during positioning of the shank relative to the head, such that the stopping surface makes contact with the inner protrusion within the lower chamber of the retainer structure when the retainer structure is mated with the capture structure, and the capture structure upper engagement surface being located above and in spaced relationship with respect to the retainer structure;
• the capture structure upper engagement surface adapted to engage the rod and receive a downward force from the rod to lock the position of the shank and retaining structure relative to the head;
• and wherein a tool seating surface is disposed on the capture structure, the projection and the capture structure tool seating surface partially defining a recess adapted for receiving a driving tool engaged with the projection and wherein the driving tool is adapted to be in contact with the capture structure tool seating surface when driving the shank body into bone.