Patent ID: 6884246

Claim:
A bone resection device for use in resection of bone during joint replacement surgery, the device comprising (a) a rotatable shaft having two cutting tools mounted on the shaft for rotation with it, each of the cutting tools being pivotally mounted on the shaft in opposed manner such that when one of the tool is caused to pivot in one direction the other tool is caused to pivot to substantially the same degree in the opposite direction, the cutting tools being arranged to cut the bone when the shaft rotates, and (b) a tool positioning mechanism mounted on the device or engaging with the device at least during use thereof and arranged to cooperate with cutting tools during rotation thereof to alter their pivotal orientations relative to the shaft such that the shape of the resected surface is determined at least in part by the tool positioning mechanism, in which: (i) the cutting edge of each of the cutting tools faces directly away from the tool positioning mechanism, and (ii) the tool positioning mechanism comprises a cam surface and cam follower assembly which controls the pivotal position of the cutting tools according to the movement of the cam follower over the cam surface during rotation of the shaft, the cam surface defining a path for the cam followers which is shaped so that the cutting tools move pivotally during rotation of the shaft to cause the shape of the bone surface that is resected by the cutting tools to be non-circular when the resected bone is viewed along the axis defined by the shaft.