Dynamic ligament balancing system

Abstract

A method and system for measuring tension, pressure, and distance of knee tissue, the system comprising a prosthetic inlay device comprising at least two platform structures, wherein each of the platforms are supported on a scissor arm structure and a coil spring, a force sensing sensor configured beneath each coil spring, and a connector cable coupled to the force sensing sensors.

What is claimed is: 
     
         1 . A system for measuring tension, pressure and distance of joint tissue, the system comprising:
 a prosthetic inlay device comprising:   at least two independent platform structures, wherein each of the independent platform structures are supported on a spring, and wherein each of the independent platform structures corresponds to a portion of a bone and is configured to variably depress the spring by the corresponding portion of the bone through a range of motion of a joint including the bone when the prosthetic inlay device is placed in situ;   a force sensing sensor configured beneath each spring, the force sensing sensor detecting pressures from depressing the spring at each of the at least two independent platform structures; and   a communication interface coupled to the force sensing sensors, the communication interface transmitting data corresponding to the detected pressures to a computing device, the data representative of a set of heights corresponding to displacement of the at least two independent platform structures associated with each of the corresponding portions of the bone at a plurality of reference angles of the joint.   
     
     
         2 . The system of  claim 1  wherein the prosthetic inlay device further comprises a pin positioning block. 
     
     
         3 . The system of  claim 1  wherein the computing device is further configured to display the set of heights corresponding to one or more of the plurality of reference angles of the joint. 
     
     
         4 . The system of  claim 1  wherein the set of heights include a pre-operative set of heights and a post-operative set of heights. 
     
     
         5 . The system of  claim 4  wherein the computing device is further configured to determine differences between the pre-operative set of heights and the post-operative set of heights. 
     
     
         6 . The system of  claim 5  wherein the computing device is further configured to indicate given ones of the plurality of reference angles that are either in-range or out-of-range based on the differences. 
     
     
         7 . The system of  claim 5  wherein the computing device is further configured to generate a color indicator based on degree of deviation of the post-operative set of heights from the pre-operative set of heights. 
     
     
         8 . A method, in a data processing system comprising a processor and a memory, for measuring tension, pressure, and distance of knee tissue, the method comprising:
 receiving, by a computing device, a first set of signals from a ligament balancing device including at least two independent platform structures, wherein each of the platform structures are supported on a spring and corresponds to a portion of a bone, and force sensing sensors that measure force applied to each of the at least two independent platform structures that variably displace each of the springs by corresponding portions of the bone through a range of motion of a knee including the bone when the ligament balancing device is placed in situ, the first set of signals representative of force applied to each of the at least two independent platform structures by the corresponding portions of the bone at one or more knee flexion angles prior to a prosthetic operation;   identifying, by the computing device, a first set of medial and lateral forces at the one or more knee flexion angles from the first set of signals;   receiving, by the computing device, a second set of signals from the ligament balancing device, the second set of signals representative of force applied to each of the at least two independent platform structures by the corresponding portions of the bone at the one or more knee flexion angles subsequent to the prosthetic operation;   identifying, by the computing device, a second set of medial and lateral forces at the one or more knee flexion angles from the second set of signals;   determining, by the computing device, a first set of heights that represent displacement of the at least two independent platform structures based on the first set of medial and lateral forces and a second set of heights correspond to displacement of the at least two independent platform structures based on and the second set of medial and lateral forces; and   displaying, by the computing system, the first set of heights and the second set of heights at the one or more knee flexion angles.   
     
     
         9 . The method of  claim 8  further comprising:
 determining, by the computing device, an amount of difference between the first set of heights and the second set of heights at each of the one or more knee flexion angles; and 
 displaying, by the computing device, an indication for the one or more knee flexion angles based on the determined amount of difference between the first set of heights and the second set of heights. 
 
     
     
         10 . The method of  claim 9  wherein the indication includes either an in-range indicator or and an out-of-range indicator based on the differences. 
     
     
         11 . The method of  claim 9  wherein the indication includes a color indicator based on degree of deviation of the second set of heights from the first set of heights