Apparatus and method for determining the tension on a ligament graft

DETAILED DESCRIPTION What is claimed is: 1.
An instrument for determining the variation in tension of a ligament graft extending between first and second fixation sites positioned on first and second articulated bones, respectively, comprising: a yoke, said yoke having means for securing said yoke to one of the first and second bones; a yoke plate rotatably mounted to said yoke; main housing means, said housing means for connection to said yoke plate; sled means slidably connected to said main housing, said sled means for connection to the ligament graft and thereby defining one of the first and second fixation sites, respectively; means for adjusting the position of said sled means relative to said housing means so as to place a desired degree of tension on the ligament graft; and transducer means associated with said means for adjusting for determining changes in tension from said desired degree as the first and second bones are moved relative to one another.
2.
The instrument of claim 1 wherein said yoke is U-shaped and wherein said means for securing includes spikes extending at an angle from the legs of said U-shaped yoke.
3.
The instrument of claim 2 additionally comprising an impactor having first surface means for connection to said yoke plate, said impactor having alignment pin means for insertion into a pilot hole drilled through said one of the bones and extending from said first surface means at an angle such that said alignment pin means is substantially parallel to said spikes, said impactor having a substantially smooth second surface opposite said first surface means.
4.
The instrument of claim 1 wherein said means for adjusting the position of said sled means includes a threaded bolt extending longitudinally from said sled means and a threaded nut, said main housing means also for preventing lateral movement of said threaded nut, said nut receiving said threaded bolt such that rotation of said nut in one direction urges said sled means toward said threaded nut and rotation in the other direction urges said sled means away from said threaded nut