Compact mechanical joint balancer
AssigneeNew York University
InventorsPeter Stanley Walker, Thomas Alfred Einhorn
Life of this patent
Estimating the term…
Abstract
The present invention relates to devices and methods for balancing joints, including knee joints. The devices convert unequal forces at a joint to a rotation or displacement of a pointer or gauge. The devices are able to display the relative difference in force between the lateral and medial sides of a joint from flexion to extension. In certain aspects, the devices are useful for balancing the knee during total knee surgery. The devices can be inserted between the trial femoral and tibial components of the knee and measures whether one condyle experiences more force than the other.
Claims30
A joint balancer device, comprising:
- a handle having a gauge;
- a lower plate attached to the handle;
- an upper plate aligned in parallel with the lower plate by a gap space, wherein the upper plate is displaceable relative to the lower plate;
- wherein the upper plate is connected by a mechanical link to the gauge, and wherein the mechanical link magnifies displacement of the upper plate such that the gauge displays the magnified displacement;
- an axle casing extending posteriorly (towards a joint) from the handle and connected at a posterior end to the lower plate, the axle casing further having a lumen;
- and
- an axle rotatably positioned within the lumen of the axle casing, the axle connected at an anterior end (away from a joint) to the mechanical link and at a posterior end to the upper plate.
A joint balancer device, comprising:
- a handle having a gauge;
- a lower plate attached to the handle;
- and
- an upper plate aligned in parallel with the lower plate by a gap space, wherein the upper plate is displaceable relative to the lower plate;
- wherein the upper plate is connected by a mechanical link to the gauge, and wherein the mechanical link magnifies displacement of the upper plate such that the gauge displays the magnified displacement, wherein the mechanical link comprises:
- a first and a second long beam adjacently positioned within a hollow interior of the handle, each long beam resting on a fulcrum on the interior of the handle and having an anterior end as a pointer of the gauge;
- a first short beam extending from a posterior end of the first long beam in a lateral direction underneath a left side of the upper plate;
- and
- a second short beam extending from a posterior end of the second long beam in a lateral direction underneath a right side of the upper plate.
Dependencies are inferred from the claim text.