US Patent 7618444 Surgical instrument for moving a vertebra

A surgical instrument includes a first device adapted to be connected to a fastener fixed to a first bone portion. A second device includes a first portion associated with the first device and a second portion for supporting a member which engages the fastener fixed to the first bone portion and secures a rod connected to the second bone portion to the fastener. The second portion is adapted for pressing the member against the rod. The first device has a part that prevents the second device from moving toward the fastener that is connected to the first device so that the member is rotated relative to the fastener but is not moved axially relative to the fastener in response to rotation of the second device.