Positioning Systems and Methods for Implanting an Energy Absorbing System

Abstract

Positioning instruments and related methods are described for implanting an energy absorbing system for treating joints. The positioning instruments and methods allow the energy absorbing system to be positioned at a joint such that the desired motion will occur for the particular design of a particular energy absorbing system which is to be implanted. The positioning instruments include a locating instrument for locating an anatomical feature and a target location for implantation of the energy absorbing system, a verification instrument for verification of the target location, a placement guide for guiding placement of a part of the energy absorbing system, and positioning device for aligning portions of the energy absorbing system.

1 . A method of implanting a device at a joint comprising:
 inserting a first reference marker into a first bone of the joint;   inserting a second reference marker into a second bone of the joint;   connecting the first and second reference markers to a verification tool;   moving the joint through a predetermined range of motion and utilizing the verification tool to determine whether the first and second reference markers move in a desired kinematic pattern with respect to one another throughout the predetermined range of motion;   relocating one of the reference markers if the desired kinematic pattern is not achieved; and   implanting the device across the joint.   
     
     
         2 . The method of  claim 1 , wherein the device is an energy absorbing device. 
     
     
         3 . The method of  claim 1 , wherein the first and second reference markers are temporary markers which are removed when the device is implanted. 
     
     
         4 . The method of  claim 1 , wherein the desired kinematic pattern includes motion of the first and second reference markers away from one another as the joint is moved through the predetermined range of motion from extension to flexion. 
     
     
         5 . The method of  claim 3 , wherein joint is a knee joint. 
     
     
         6 . The method of  claim 1 , wherein the first and second markers comprise elongated members having an end configured for inserting into bone and a free end, and wherein the verification tool has openings for receiving the free ends of the elongated members. 
     
     
         7 . The method of  claim 1 , wherein the verification tool includes an indicator which indicates whether the first and second reference markers move in a desired kinematic pattern. 
     
     
         8 . The method of  claim 5 , wherein the second marker is inserted into the second bone through the opening in the verification tool. 
     
     
         9 . The method of  claim 1 , wherein the verification tool is configured to measure a distance between the first and second reference markers while the joint is moved through the predetermined range of motion. 
     
     
         10 . The method of  claim 1 , wherein the first and second markers are K-wires and are inserted along substantially parallel paths. 
     
     
         11 . The method of  claim 1 , wherein the joint is a knee and the first marker is positioned on a femur relative to a midpoint of Blumensaat's line. 
     
     
         12 . A verification tool for verification of a location for implantation of an extra-articular energy absorbing device at a joint, the tool comprising:
 a tool body;   a first connection member on the tool body, the first connection member configured to be connected to a first reference marker located in a first bone, the first connection member allowing rotation of the tool with respect to the first bone;   a second connection member on the tool body, the second connection member configured to be connected to a second reference marker located in a second bone, the second connection member allowing rotation of the tool with respect to the second bone, wherein at least one of the first and second connection members is movable with respect to the tool body; and   a gauge configured to provide a user with information about the location of at least one of the first and second reference markers as the joint is articulated.   
     
     
         13 . The tool of  claim 12 , wherein the at least on of the first and second connection members is movable with respect to the tool body solely in one dimension. 
     
     
         14 . The tool of  claim 12 , further comprising an indicator configured to determine whether the first and second reference markers move in a desired kinematic pattern. 
     
     
         15 . The tool of  claim 14 , wherein the indicator is a visual indicator. 
     
     
         16 . The tool of  claim 14 , wherein the desired kinematic pattern is a pattern in which the first and second reference markers move apart as the joint moves from extension to about 45 degrees of flexion. 
     
     
         17 . A system for placing an energy absorbing device at a joint comprising:
 a base configured to be secured to a bone adjacent a joint;   a placement guide removably attachable to the base, wherein the placement guide includes an offset member one end of which is connected to the placement guide and an opposite end of which is configured to contact the bone.   
     
     
         18 . The system of  claim 17 , wherein the placement guide is removable from the base after the base has been secured to the bone. 
     
     
         19 . The system of  claim 17 , wherein the offset member is configured to slide over a reference wire fixed to the bone. 
     
     
         20 . The system of  claim 17 , wherein the offset member is pivotable with respect to the base when the placement guide is attached to the base. 
     
     
         21 . The system of  claim 17 , wherein the placement guide further comprises an elongate member extending from the guide in a direction towards an opposite bone of the joint and configured for orienting the base on the bone. 
     
     
         22 . A tool for locating a center of rotation for an implantable articulating joint device, the tool comprising:
 a tool body having at least one radiographic marker configured for locating an anatomical reference location on a bone; and   means for marking a target location for an implantable articulating joint device at a predetermined distance and direction away from the anatomical reference location.   
     
     
         23 . The tool of  claim 22 , wherein the anatomical reference location is on a femur at the center of Blumensaat's line. 
     
     
         24 . The tool of  claim 22 , wherein the radiographic marker comprises concentric radiopaque circles. 
     
     
         25 . The tool of  claim 22 , wherein the means for marking is an opening configured to receive a marker which is inserted into the bone. 
     
     
         26 . The tool of  claim 22 , wherein the target location is a center of rotation for the implantable articulating joint device. 
     
     
         27 . A method for locating a center of rotation for an implantable articulating joint device, the method comprising:
 locating an anatomical reference location on a bone with a tool having radiopaque markers; and   marking a target location for an implantable articulating joint device at a predetermined distance and direction away from the anatomical reference location by inserting a marker through an opening in the tool.   
     
     
         28 . The method of  claim 27 , wherein the target location is a center of rotation for the implantable articulating joint device and further comprising implanting the articulating joint device. 
     
     
         29 . A method of implanting an energy absorbing device at a joint comprising:
 securing a first base member to a bone on a first side of a joint;   affixing an absorber to the first base member, the absorber having at least one articulation;   temporarily restraining the articulation of the absorber to a limited range of motion less the a full range of motion of the articulation with a removable restraint;   positioning and securing a second base member to a bone on a second side of the joint while the articulation of the absorber is temporarily restrained; and   removing the restraint.   
     
     
         30 . The method of  claim 29 , wherein the restraint is a positioning collar arranged to be placed between the first base and the absorber to limit articulation of the absorber. 
     
     
         31 . A system for placing an energy absorbing device at a joint comprising:
 a base configured to be secured to a bone adjacent a joint and including a first placement guide mounting surface and a first connector component;   a placement guide including a second placement guide mounting surface, a second connector component adapted to mate with the first connector component, and an offset member, the placement guide being attachable to the base in an attached position such that the first and second placement guide mounting surfaces abut when the first and second connector components mate.   
     
     
         32 . The system of  claim 31 , wherein the placement guide is removable from the base after the base has been secured to the bone. 
     
     
         33 . The system of  claim 31 , wherein the offset member has a first and a second end, the first end of the offset member being configured to contact the bone when the placement guide is in the attached position and the base is in a position at which it is to be secured to the bone. 
     
     
         34 . The system of  claim 31 , wherein the offset member comprises a longitudinal opening and is configured such that a reference marker fixed to the bone is adapted to extend through the longitudinal opening. 
     
     
         35 . The system of  claim 31 , wherein the placement guide is attachable to the base in only one attached position. 
     
     
         36 . The system of  claim 31 , wherein the placement guide further comprises an elongate member extending from the guide in a direction towards an opposite bone of the joint and configured for orienting the base on the bone. 
     
     
         37 . The system of  claim 31 , wherein the placement guide includes a locking arm adapted to engage with the base for locking the placement guide in the attached position. 
     
     
         38 . The system of  claim 37 , comprising a removable pin adapted to engage the locking arm to prevent unlocking of the placement guide from the attached position. 
     
     
         39 . A method for positioning a base for an implant at a joint, comprising:
 inserting a first elongated reference marker into a first bone of the joint so that one end of the first reference marker is inserted into the bone and the other end of the first reference marker is free;   placing a preassembled combination of a base and a placement guide on the bone of the joint so that the first reference marker extends through a first guide hole in the placement guide;   inserting a second elongated reference marker through a second guide hole in the placement guide and into the bone of the joint while orienting the combination and the second reference marker so that, when the second reference marker is inserted into the bone, the second reference marker extends in a predetermined relation to the first bone and a second bone of the joint.   
     
     
         40 . The method of  claim 39 , comprising detaching the placement guide from the base by moving a locking arm of the placement guide from a locking position in which the locking arm locks the placement guide relative to the base to an unlocked position. 
     
     
         41 . A tool for selecting one base from among a plurality of bases having different base geometries for an implant at a joint, comprising:
 a tool body having a bone contacting surface shape generally corresponding to a bone contacting surface shape of the plurality of bases from which the one base is to be selected;   a guide opening on the tool body through which an elongated reference marker is adapted to extend;   indicia corresponding to at least some of the plurality of bases,   wherein, when the tool body is positioned on a bone of the joint so that the reference marker extends through the guide opening and the tool body is in a desired alignment with the bone, the reference marker is disposed in a position relative to the indicia that indicates one base is to be selected.   
     
     
         42 . The tool of  claim 41 , wherein the guide opening is generally conical, with a wide end of the cone being disposed on a side of the tool body opposite a side of the tool body intended to face the bone. 
     
     
         43 . The tool of  claim 42 , wherein the indicia are disposed on the tool body at the wide end of the cone of the guide opening. 
     
     
         44 . A method for selecting a base from among a plurality of bases having different base geometries for an implant at a joint, comprising:
 inserting an elongated reference marker into a bone of the joint so that one end of the reference marker is inserted into the bone and the other end of the reference marker is free;   positioning a trial so that a surface of the trial is in a desired alignment with the portion of the bone and so that the free end of the reference marker extends through a guide opening on the trial; and   selecting one base from among the plurality bases depending upon a position of the reference marker relative to one or more indicia associated with the guide opening.