A polyaxial bone screw assembly comprises a shank (4) having an upper portion (8) and a body (6) for fixation to a bone (15), a receiver (10) defining an open channel (56) with the shank being swivelable during positioning with respect to the receiver and a retaining and articulating structure (12) attachable to the shank upper portion and having a formation (106) formed in a top thereof for receiving a driving tool (31) for driving the shank into bone, the shank having a cannulation (44) along its entire length. The driving tool (31) also has a cannulation (176), the arrangement being such that, when inserting the shank (4) in the bone, a pin (49) passing through both cannulations (44, 176) serves as a guide.
