Apparatus and method for evaluating joint performance
The present invention is generally directed to apparatuses and methods for evaluating the amount of “play” in a joint. In one embodiment, an apparatus is provided that quantifies the rotation of the tibia in response to a known torque. The apparatus is configured to minimize the influence of other joints on the rotation analysis. Other embodiments provide data related to movement of the tibia in other degrees of freedom.
1. An apparatus for evaluating the performance of the knee of a patient's leg in multiple degrees of freedom, said patient having a femur, a knee, a tibia, an ankle and a foot, said apparatus comprising:
A) a frame;
B) a device for securing said femur of said patient relative to said frame;
C) a foot accepting element configured to detachably receive and secure at least a portion of the foot such that force can be transferred from said foot accepting element through said foot to said tibia;
D) a multi-axis pivoting assembly attached intermediate said foot accepting element and said frame, said multi-axis pivoting assembly configured to facilitate multi-axis pivoting of said foot accepting element relative to said frame and said multi-axis pivoting assembly itself comprising:
1) a first pivot subassembly configured to transfer a first torque to said tibia causing movement of said tibia relative to said femur in a first degree of freedom, wherein said first pivot subassembly includes first and second portions having a pivotable connection therebetween along a first pivot axis, wherein said first pivot axis lies in a plane which is further distal than the entirety of the foot of said patient than is said foot accepting element in use, said distal relationship being relative to the leg of the patient; and
2) a second pivot subassembly configured to transfer a second torque to said tibia causing movement of said tibia relative to said femur in a second degree of freedom, wherein said second pivot subassembly includes first and second portions having a pivotable connection therebetween along a second pivot axis; wherein said second pivot axis is at an angle relative to said first pivot axis and is configured to provide a torque about the longitudinal axis of said tibia of said patient in use;
E) a first angle measuring device configured to measure angular displacement of said first pivot subassembly in response to said first torque; and
F) a second angle measuring device configured to measure angular displacement of said second pivot subassembly in response to said second torque.
2. The apparatus as claimed in claim 1 , wherein said first and second pivot subassemblies are selectively independently lockable such that one of said subassemblies does not undergo pivoting while the other is undergoing pivoting.