A clamp device, cutting guide, and clamp slider used together in preparation to cutting of the distal end of the femur bone during total knee replacement surgery. The clamp device includes an upper arm and a lower arm rotatably secured to one another in a scissor-like manner. A curved movable component is rotatably secured to the proximal end of the lower arm. The clamp device is positioned around a portion of the distal end of the femur bone so that the distal end of the upper arm grasps a posterior ridge of the femur bone and the movable component of the lower arm is positioned along the contour of the deepest part of the trochlear groove, thereby defining a plane through the deepest part of the trochlear groove of the femur bone. Next, a clamp slider is removably secured to a cutting guide so that channels defined in the clamp slider and cutting guide are substantially aligned with one another. The assembled clamp slider and cutting guide are then slid over the clamp and rotated until the clamp is received in the channels with the cutting guide in contact with an anterior portion of the femur bone. Then the cutting guide is positioned so that arms projecting from each side are substantially aligned with a center of the medial or lateral epicondyle of the femur bone. Lastly, the clamp slider and clamp are removed, whereby the cutting guide remains properly aligned on the femur bone in order to ensure the correct angle of the cuts in the femur bone.