Two degree of freedom system and method for spinal applications

Abstract

A method and system to align a pin or drill a tunnel along a single line in space with a two degree of freedom (2-DOF) surgical device in a patient is provided. A plane is defined relative to a desired location for an implant or tunnel on a bone, where the implant or tunnel has an axis. An end-effector of the 2-DOF surgical device is aligned coincident with the plane, and the 2-DOF surgical device is moved side-to until a first indicator signals when the end-effector aligns with an entry point for the desired location for the implant or tunnel on the bone. A tip of the end-effector is anchored into the bone at the entry point; and the 2-DOF surgical device is rotated about the anchored tip until a second indicator signals when the end-effector aligns with the axis of the implant or tunnel at the desired location.

1 . A method to align a 2-DOF hand-held surgical device along an axis, comprising:
 defining a plane relative to a desired location for an implant or tunnel on a bone, said implant or tunnel having an axis;   aligning an end-effector of the 2-DOF surgical device coincident with the plane; and   moving the 2-DOF surgical device about the bone while the end-effector maintains coincidence with the plane until a first indicator signals when the end-effector aligns with at least one of: an entry point for the desired location for the implant or tunnel on the bone; or the axis of the implant or tunnel at the desired location.   
     
     
         2 . The method of  claim 1  further comprising:
 moving the 2-DOF surgical device side-to-side while the end-effector maintains coincidence with the plane until the first indicator signals when the end-effector aligns with the entry point for the desired location for the implant or tunnel on the bone; 
 anchoring a tip of the end-effector into the bone at the entry point; and 
 rotating the 2-DOF surgical device about the anchored tip while the end-effector remains coincident with the plane until a second indicator signals when the end-effector aligns with the axis of the implant or tunnel at the desired location. 
 
     
     
         3 . The method of  claim 1  further comprising inserting the end-effector into the bone. 
     
     
         4 . The method of  claim 2  wherein the first indicator and the second indicator are the same indicator. 
     
     
         5 . The method of  claim 1  wherein the first indicator is at least one of: a red and a green signal; and a blinking light that changes frequency based on how closely the end-effector aligns with the entry point or axis of the implant or tunnel at the desired location. 
     
     
         6 . The method of  claim 2  wherein the second indicator is at least one of: a red and a green signal; and a blinking light that changes frequency based on how closely the end-effector aligns with the axis of the implant or tunnel at the desired location. 
     
     
         7 . The method of  claim 1  wherein the first indicator is displayed using a monitor, or an on-board indicator of the 2-DOF surgical tool that provides feedback to the user. 
     
     
         8 . The method of  claim 7  wherein the on-board indicator comprises one or more light emitting diode (LED) for direct visual feedback when the 2-DOF surgical tool is aligned with at least one of the entry point or the axis of the implant or tunnel. 
     
     
         9 . The method of  claim 8  further comprising displaying a virtual model of the bone is on the monitor, where the defined plane, axis of the implant or tunnel, and a real-time axis of the end-effector are superimposed on the virtual bone model. 
     
     
         10 . The method of  claim 10  further comprising aligning the superimposed real-time axis of the end-effector with the superimposed axis of the implant or tunnel. 
     
     
         11 . The method of  claim 8  wherein the monitor further provides visual feedback as at least one of: a red and a green signal; and a blinking light that changes frequency based on how closely the end-effectors aligns with the entry point. 
     
     
         12 . The method of  claim 2  wherein the second indicator is a power control to the end-effector wherein when the end-effector aligns with the axis of the implant or tunnel, the power to a drill of the end-effector is automatically turned on to insert the end-effector into the bone; and
 wherein if the end-effector veers off-axis from the axis, or the tip moves from the entry point, then power to the drill is automatically turned off. 
 
     
     
         13 . The method of  claim 1  wherein the end-effector comprises one of a dill bit, pedicle screw, bone screw, bone pin, a hollow drill bit, burr, bone nail, a reamer, broach, or an implant. 
     
     
         14 . The method of  claim 1  wherein the plane is defined using pre-operative bone data (CT, MRI, images, 3D bone models) and a pre-operative planning software program. 
     
     
         15 . The method of  claim 1  wherein the desired placement for the implant or tunnel is defined using tools or widgets in a planning software program, the tool and widgets comprising at least one of virtual models of tunnels, virtual models of an implant, a set of points, lines, splines, or planes positionable relative to a set of pre-operative bone data, and a drawing toolbox. 
     
     
         16 . A system for implementing the method  claim 1  wherein said system comprises:
 a computing system; 
 an articulating 2-DOF surgical device; and 
 a tracking system. 
 
     
     
         17 . The system of  claim 16  wherein the articulating 2-DOF surgical device comprises:
 a working portion configured to articulate; 
 a hand-held portion pivotably connected to the working portion by a front linear rail and a rear linear rail, said front linear rail and said rear linear rail actuated by a set of components in the hand-held portion to adjust pitch and translation of the working portion relative to the hand-held portion, said front linear rail and said rear linear rail each having a first end and a second end; and 
 a tracking array having a set of three or more fiducial markers rigidly attached to the working portion to permit a tracking system to track a position and orientation (POSE) of the working portion. 
 
     
     
         18 . The system of  claim 17  further comprising:
 a front actuator that powers a front ball screw, and a back actuator that powers a back ball screw, where the first end of both said front linear rail and said rear linear rail are each attached to said working portion via a set of hinges allowing said working portion to pivot relative to said front linear rail and said rear linear rail; and 
 a set of ball nuts integrally attached at a second end of both said front linear rail and said rear linear rail, said set of ball nuts in mechanical communication with both said front ball screw and said back ball screw; said set of ball nuts translate along the axis of the ball screws to adjust the pitch and translation of said working portion. 
 
     
     
         19 . The system of  claim 16  wherein the articulating 2-DOF surgical device further comprises an on-board indicator configured to provide feedback to a user based on an actual position of said working portion relative to a desired position for said working portion.