Instrument and method for in situ rod adjustment

A method for advancing a fixation rod relative to an implanted screw assembly, comprising:

• inserting an instrument comprising:
• an outer shaft including a lumen extending from a proximal end to a distal end of the outer shaft;
• an inner shaft within the lumen;
• a roller rotatably coupled with the distal end at an axis and configured to engage the fixation rod;
• and
• an actuator operably coupled with the inner shaft to translate the inner shaft within the lumen and cause rotation of the roller to impart linear movement on the fixation rod;
• positioning the actuator to impart linear movement on the inner shaft to engage the roller with the fixation rod in a drive position;
• and
• positioning the actuator to impart linear movement on the inner shaft to rotate the roller while engaged with the fixation rod;
• wherein the actuator is advanced to the drive position in which the inner shaft advances distally causing increased friction between the roller and the fixation rod.

A method for advancing a fixation rod relative to an implanted screw assembly, comprising:

• inserting an instrument comprising:
• an outer shaft including a lumen extending from a proximal end to a distal end of the outer shaft;
• an inner shaft within the lumen;
• a roller rotatably coupled with the distal end at an axis and configured to engage the fixation rod;
• and
• an actuator operably coupled with the inner shaft to translate the inner shaft within the lumen and cause rotation of the roller to impart linear movement on the fixation rod;
• positioning the actuator to impart linear movement on the inner shaft to engage the roller with the fixation rod in a drive position;
• and
• positioning the actuator to impart linear movement on the inner shaft to rotate the roller while engaged with the fixation rod;
• wherein the actuator advances the inner shaft distally causing the roller to rotate and impart a force to translate the fixation rod.