Apparatus and method for joint characterization and treatment

Abstract

A method for imparting tension across a human knee joint which includes a femur bone, a tibia bone, a patella bone, a patellar tendon, and ligaments, wherein the ligaments and patellar tendon are under anatomical tension to connect the femur and tibia together, creating a load-bearing articulating joint. The method includes: providing a tensioning device, including: a baseplate; a top plate; and a linkage interconnecting the baseplate and the top plate and operable to move the tensioning device between retracted and extended positions, wherein the top plate is pivotally connected to the linkage so as to be able to freely pivot about a pivot axis; positioning the tensioning device between the femur and the tibia; applying an actuating force to the linkage to move the tensioning device towards the extended position, so as to impart a controlled separating force driving the femur and tibia apart to extend the ligaments.

What is claimed is: 
     
         1 . A method for imparting tension across a human knee joint which includes a femur bone, a tibia bone, a patella bone, a patellar tendon, and ligaments, wherein the ligaments and patellar tendon are under anatomical tension to connect the femur and tibia together, creating a load-bearing articulating joint, the method comprising:
 providing a tensioning device, including:   a baseplate;
 a top plate; and 
 a linkage interconnecting the baseplate and the top plate and operable to move the tensioning device between retracted and extended positions, wherein the top plate is pivotally connected to the linkage so as to be able to freely pivot about a pivot axis; 
   positioning the tensioning device between the femur and the tibia;   applying an actuating force to the linkage to move the tensioning device towards the extended position, so as to impart a controlled separating force driving the femur and tibia apart to extend the ligaments.   
     
     
         2 . The method of  claim 1  wherein the actuating force is applied by an actuating instrument coupled to the tensioning device. 
     
     
         3 . The method of  claim 1  further comprising taking measurements of distance and angle between articulating surfaces of the femur and tibia. 
     
     
         4 . The method of  claim 3  wherein the patella and patellar tendon are disposed in a normal anatomical position the measurements of distance and angle are taken. 
     
     
         5 . The method of  claim 3  wherein at least one of the distal and posterior surfaces of the femoral condyles have been cut away to create a flat surface from which measurements of distance and angle can be referenced when the knee joint is in extension and flexion. 
     
     
         6 . The method of  claim 3  further comprising:
 prior to the step of applying an actuating force, inserting a trial component to replicate an articulating geometry of a final implantable device; 
 moving the femur and tibia throughout at least a portion of a range of motion of the knee joint; and 
 taking the measurements of distance and angle as the femur and tibia are moved. 
 
     
     
         7 . The method of  claim 2  further comprising:
 moving the femur and tibia throughout at least a portion of a range of motion of the knee joint; and 
 taking the measurements of distance and angle as the femur and tibia are moved, wherein the proximal end of the tibia has been cut away to create a flat surface from which the measurements of distance and angle can be referenced relative to uncut native surfaced of the condyles of the femur. 
 
     
     
         8 . The method of  claim 1  further comprising:
 moving the femur and tibia throughout at least a portion of a range of motion of the knee joint; and 
 measuring a change in separating force between the femur and tibia as the femur and tibia articulates during the movement. 
 
     
     
         9 . The method of  claim 1  further comprising measuring at least one of: extension gap displacement, flexion gap displacement, and varus or valgus angle by reading numerical analog values indicated on the tensioning device mechanically. 
     
     
         10 . The method of  claim 1  wherein numerical values of at least one of gap displacement, and separating force are sensed electronically from the tensioning device and indicated on a remote device. 
     
     
         11 . The method of  claim 1  wherein numerical values of a least one of gap displacement and angle are interpolated by tracking the real-time position of the femur and tibia bones relative to one another in 3-D space using tracking markers coupled to the femur and tibia bones. 
     
     
         12 . A method for balancing a gap between the tibia and the femur of a knee joint, comprising:
 providing a gap tensioning apparatus including:   a gap tensioner including:
 a baseplate; 
 a top plate; 
 a linkage interconnecting the baseplate and the top plate and operable to move the gap tensioner between retracted and extended positions; and 
 wherein the top plate is pivotally connected to the linkage so as to be able to freely pivot about a pivot axis; 
   inserting the gap tensioner between the tibia and the femur, with the gap tensioner in the retracted position;   actuating the linkage to move the gap tensioner towards the extended position, so as to urge the tibia and the femur apart and apply tension to the medial and lateral collateral ligaments of the knee joint; and   selectively augmenting or releasing at least one of the medial and lateral collateral ligaments so as to change a varus or valgus angulation of the knee joint.   
     
     
         13 . A method of evaluating a human knee joint which includes a femur bone, a tibia bone, a patella bone, a patellar tendon, and ligaments, wherein the ligaments and patellar tendon are under anatomical tension to connect the femur and tibia together, creating a load-bearing articulating joint, the method comprising:
 associating at least one force transducer with the knee joint, the force transducer having at least a two-axis array resolution;   providing an electronic receiving device;   moving the knee joint through at least a portion of its range of motion;   while moving the knee joint, using the electronic receiving device to collect data from the at least one force transducer;   processing the collected position data to produce a geometric model of at least a portion of the knee joint; and   computing one or more tool paths passing through the knee joint.   
     
     
         14 . The method of  claim 13  further comprising:
 prior to the step of moving the knee joint through at least a portion of its range of motion, making a tibial cut along a first cutting plane to cut away a proximal portion of the tibia; 
 providing a gap tensioning apparatus operable to move between retracted and extended positions for distracting the knee joint while permitting varus/valgus angulation, where the at least one force transducer is coupled to the gap tensioning apparatus; and 
 inserting the gap tensioner between the tibia and the femur, with the gap tensioner in the retracted position; and 
 moving the gap tensioner towards the extended position, so as to urge the tibia and the femur apart and apply tension to the medial and lateral collateral ligaments of the knee joint. 
 
     
     
         15 . The method of  claim 13  further comprising:
 associating at least one tracking marker with the knee joint; and 
 while moving the knee joint, using the electronic receiving device to collect the force data and to collect position data from the at least one tracking marker, the force data being correlated to the position data. 
 
     
     
         16 . The method of  claim 13  further comprising:
 coupling at least one tracking marker to the knee joint; 
 receiving data representing an actual position and orientation of the tool relative to the at least one tracking marker; 
 moving a tool along the one or more tool paths, with reference to the data, so as to remove bone from the knee joint, thereby forming a machined feature in the knee joint. 
 
     
     
         17 . The method of  claim 16  further comprising:
 displaying on a display an image representing the actual position and orientation of the tool relative to the computed one or more tool paths; and 
 moving the tool along the one or more tool paths, with reference to the displayed image. 
 
     
     
         18 . The method of  claim 16  wherein the step of moving the tool with reference to the received data comprises:
 determining a difference between the actual position and orientation of the tool and a position and orientation lying on the computed one or more tool paths; and 
 using at least one actuator coupled to the tool, moving the tool in a direction so as to reduce the difference. 
 
     
     
         19 . The method of  claim 13  wherein the at least one force transducer is operable to map a matrix of force magnitudes and direction vectors. 
     
     
         20 . The method of  claim 13  wherein the at least one force transducer is operable to map a matrix of force magnitudes and direction vectors on a nonplanar surface. 
     
     
         21 . The method of  claim 13  wherein the electronic receiving device is inserted as a tibia tray liner for gathering data and confirmation of tibia tray liner thickness with a trial or final tibia tray and a trial or final femoral component in place. 
     
     
         22 . The method of  claim 13  wherein the data is compiled in a database and learning system.