Surgical instrument for moving a vertebra

A surgical instrument for moving a first bone portion of a body relative to a second bone portion of the body, the surgical instrument comprising:

• a cannula for forming a passage into the body and for defining an operative space adjacent the first and second bone portions;
• a first device that is extendable through the passage formed by the cannula, the first device including an actuatable clamp for clamping on a fastener fixed to the first bone portion and a threaded carriage that is movable axially relative to the clamp in a direction away from the first bone portion when subjected to a predetermined axial load;
• and
• a second device that is also extendable through the passage formed by the cannula, the second device including a threaded portion adapted for threaded engagement with the carriage of the first device and an end 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 end portion being adapted for pressing the member against the rod, relative rotation between the first and second devices during threaded engagement of the carriage of the first device and the threaded portion of the second device causing relative axial movement between the second device and the carriage of the first device,
• the carriage being stationary relative to the clamp of the first device when a force necessary to produce relative movement between the first and second bone portions is below the predetermined axial load so that relative rotation between the first and second devices moves the clamp and the fastener fixed to the first bone portion and the first bone portion relative to the second bone portion and relative to the rod.

A surgical instrument for threadedly connecting a member and a fastener, the surgical instrument comprising:

• a first device including an actuatable clamp for clamping on the fastener and a threaded carriage that is movable axially relative to the clamp in a direction away from the fastener when subjected to a predetermined axial load;
• and
• a second device including a threaded portion adapted for threaded engagement with the carriage of the first device and an end portion for supporting the member to be threadedly connected to the fastener, relative rotation between the first and second devices during threaded engagement of the carriage of the first device and the threaded portion of the second device causing relative axial movement between the second device and the carriage of the first device,
• the carriage moving axially away from the fastener that is clamped by the clamp of the first device when a force applied exceeds the predetermined axial load so that the member is rotated relative to the fastener but is not moved axially relative to the fastener in response to relative rotation between the first and second devices,
• the carriage being stationary relative to the fastener that is clamped by the clamp of the first device when the force applied is below the predetermined axial load so that relative rotation between the first and second devices results in the member being threadedly connected to the fastener.