9. The spinal fixation system of claim 8 , wherein the cap has a distal bearing surface that is chamfered or domed.
9. The spinal fixation system of claim 8 , wherein the cap has a distal bearing surface that is chamfered or domed. 11. The spinal fixation system of claim 9 , further including a floating washer, the floating washer including a bearing surface that mates with the distal bearing surface of the cap, and rails that slidably engage the connecting plate, whereby the connecting plate is fixed to the bone anchor by compression between the floating washer and the bone anchor.