A system for correcting a position of bones, bone parts, or vertebrae includes a first bone anchor including a shank for anchoring in bone and a receiver for connecting a rod to the shank, a second bone anchor including a shank for anchoring in bone and a receiver for connecting the rod to the shank, and an instrument including a positioning member, a first coupling member for coupling the positioning member to the first bone anchor, and a second coupling member for coupling the positioning member to the second bone anchor. The first and second coupling members are movable relative to one another. The receiver is pivotable relative to the shank for at least one bone anchor. The at least one bone anchor can assume a locked configuration where an angular position of the receiver relative to the shank is locked while the rod remains movable relative to the receiver.
