Abstract: A bone resection device (30) for use in resection of bone during joint replacement surgery includes a rotatable shaft (4) having mounted thereon for rotation with the shaft at least two blades (3) carrying at least one cutting edge (3a). The bone resection device (30) further includes a blade positioning mechanism (2) mounted on the device or engaging with the device at least during use thereof and arranged to cooperate with the blades during rotation thereof to alter the orientation of the cutting edge relative to the shaft such that the shape of the resected surface is determined at least in part by the blade positioning mechanism.