Abstract: A distractor instrument for use in knee joint surgery is provided that includes a tibial plate, a femoral plate, a tibial arm having a plate end and a control end, wherein the tibial plate is fastened to the plate end of the tibial arm at its anterior edge, and wherein, when the tibial plate is engaged with the tibia, the tibial arm is configured to extend from the tibial plate generally medially or laterally of the knee joint. The distractor instrument also includes a femoral arm having a plate end and a control end, wherein the femoral plate is fastened to the plate end of the femoral arm, and wherein, when the femoral plate is engaged with the femur, the femoral arm extends from the femoral plate generally aligned with the tibial arm.

Abstract: A technique for locating an axis of a bone, which extends through the center of rotation of the bone around a joint between that bone and another bone, involves a. moving the bone in a plane about the said joint, between a first point and a second point, b. locating a third point which is equidistant from the first and second points, and c. locating the axis which passes through the third point, perpendicular to a line which connects the first and second points. The invention provides an instrument for performing this technique.

Abstract: An instrument assembly for use in knee joint replacement surgery is provided including a base instrument having a tibial plate, a femoral plate, a tibial arm having a plate end and a control end, a femoral arm having a plate end and a control end, wherein the femoral plate is rotatably fastened to the plate end of the femoral arm. The assembly also includes a distractor mechanism configured to act between the tibial arm and the femoral arm at a point between their respective plate ends and control ends by which the distance between the plate ends of the arms can be adjusted and an ancillary instrument mountable on the base instrument and configured such that the position of the ancillary instrument relative to the tibial plate is fixed during subsequent steps in the knee replacement procedure, while the knee joint is distracted as a result of forces applied across the joint between the tibial plate and the femoral plate.

Abstract: A method for locating the mechanical axis of a long bone involves generating an image of the long bone and determining the angle between the mechanical axis of the bone and a reference axis, which contains at least two reference points towards one end of the bone. A reference arm is positioned relative to the at least two predetermined reference points, and the mechanical axis is located relative to the reference arm with reference to the previously determined angle.

Abstract: A guide block for use in surgery to locate a surgical tool accurately relative to an anatomical feature comprises a fixation part which can be fastened directly to the patient's tissue, and a guide part having at least one structural feature to engage a surgical tool to ensure that the tool is located appropriately relative to the patient's tissue. The guide part is mounted on the fixation part. The guide block includes at least two drives for adjusting the position of the guide part relative to the fixation part, so that the position of the guide part relative to the fixation part can be adjusted in at least two degrees of freedom. The fixation part of the guide block includes a housing which is hollow, and the drives are located inside the housing.

Abstract: A burr guide assembly is described for guiding a burr tool during a procedure wherein the burr tool is used to cut a bone. The guide assembly includes a housing which is configured to be attached to the bone, a guide sleeve attached to the housing such that the guide sleeve can freely pivot about a pivot axis within a defined range, and a burr tool. The guide sleeve has a bore that extends along its length, which is located eccentrically within the guide sleeve. The burr tool has a cutting portion that is configured to be at least partially disposed within the bore. The guide sleeve is mounted within the housing such that the cutting portion is substantially restricted to movement in a plane that is perpendicular to the pivot axis.

Abstract: A bone marker for use in image guided surgery comprises a support having an anchor mechanism for anchoring the support in a bone. The marker includes at least one reference member which can be detected by an image guided system and which is attached to the support. The support has at least one limb which is resiliently deformable.

Abstract: A bone clamp for securing a surgical instrument to a bone including a body on which the instrument can be mounted, a first and second contacting arms, each of which has a first end that is pivotally connected to the body, and a second end for gripping the bone, whenever the first and second contacting arms are connected to the body at or towards opposite ends thereof so that, when the body is positioned adjacent to the bone, the arms can grip the bone on opposite surfaces thereof, and an actuator which can be moved between engaged and disengaged positions. When the actuator is in its disengaged position, the contacting arms can pivot independently with respect to each other, and when the actuator is in its engaged position, the pivoting movement of one contact arm is accompanied by approximately equal pivoting movement of the other contact arm in the opposite direction.

Abstract: A technique for locating an axis of a bone, which extends through the centre of rotation of the bone around a joint between that bone and another bone, involves a. moving the bone in a plane about the said joint, between a first point and a second point, b. locating a third point which is equidistant from the first and second points, and c. locating the axis which passes through the third point, perpendicular to a line which connects the first and second points. The invention provides an instrument for performing this technique.

Abstract: A distractor instrument for use in knee joint surgery is provided that includes a tibial plate, a femoral plate, a tibial arm having a plate end and a control end, wherein the tibial plate is fastened to the plate end of the tibial arm at its anterior edge, and wherein, when the tibial plate is engaged with the tibia, the tibial arm is configured to extend from the tibial plate generally medially or laterally of the knee joint. The distractor instrument also includes a femoral arm having a plate end and a control end, wherein the femoral plate is fastened to the plate end of the femoral arm, and wherein, when the femoral plate is engaged with the femur, the femoral arm extends from the femoral plate generally aligned with the tibial arm.

Abstract: An instrument assembly for use in knee joint replacement surgery is provided including a base instrument having a tibial plate, a femoral plate, a tibial arm having a plate end and a control end, a femoral arm having a plate end and a control end, wherein the femoral plate is rotatably fastened to the plate end of the femoral arm. The assembly also includes a distractor mechanism configured to act between the tibial arm and the femoral arm at a point between their respective plate ends and control ends by which the distance between the plate ends of the arms can be adjusted and an ancillary instrument mountable on the base instrument and configured such that the position of the ancillary instrument relative to the tibial plate is fixed during subsequent steps in the knee replacement procedure, while the knee joint is distracted as a result of forces applied across the joint between the tibial plate and the femoral plate.

Abstract: A method for locating the mechanical axis of a long bone involves generating an image of the long bone and determining the angle between the mechanical axis of the bone and a reference axis, which contains at least two reference points towards one end of the bone. A reference arm is positioned relative to the at least two predetermined reference points, and the mechanical axis is located relative to the reference arm with reference to the previously determined angle.

Abstract: A burr guide assembly for guiding a burr tool during a procedure in which the burr tool is used to cut a bone. The burr guide assembly comprises a housing which can be fastened to the bone and a guide sleeve which is pivotally mounted in the housing. The guide sleeve has a bore extending along its length in which a burr tool can be received such that the cutting portion of the burr tool extends from the sleeve towards the bone which is to be cut. The bore is located eccentrically within the guide sleeve. Further, the sleeve is mounted in the housing for pivotal movement around an axis so that the cutting portion of the burr tool is restricted to movement in a plane which is perpendicular to that axis. The assembly also includes a burr tool which is a sliding fit in the guide sleeve.

Abstract: A guide assembly for guiding a bone preparation tool in relation to a patient's bone in an orthopaedic surgical procedure, includes a guide member which has a first face which can be positioned against a surface of the bone which is to be prepared using a bone preparation tool, and an opening extending through the guide member through which the bone preparation tool can be positioned against the bone surface, and which has one of a spigot and a socket formed on it.

Abstract: A bone marker for use in image guided surgery comprises a support having an anchor mechanism for anchoring the support in a bone. The marker includes at least one reference member which can be detected by an image guided system and which is attached to the support. The support has at least one limb which is resiliently deformable.

Abstract: A guide block for use in surgery to locate a surgical tool accurately relative to an anatomical feature comprises a fixation part which can be fastened directly to the patient's tissue, and a guide part having at least one structural feature to engage a surgical tool to ensure that the tool is located appropriately relative to the patient's tissue. The guide part is mounted on the fixation part. The guide block includes at least two drives for adjusting the position of the guide part relative to the fixation part, so that the position of the guide part relative to the fixation part can be adjusted in at least two degrees of freedom. The fixation part of the guide block includes a housing which is hollow, and the drives are located inside the housing.

Abstract: A bone clamp for securing a surgical instrument to a bone including a body on which the instrument can be mounted, a first and second contacting arms, each of which has a first end that is pivotally connected to the body, and a second end for gripping the bone, whenever the first and second contacting arms are connected to the body at or towards opposite ends thereof so that, when the body is positioned adjacent to the bone, the arms can grip the bone on opposite surfaces thereof, and an actuator which can be moved between engaged and disengaged positions. When the actuator is in its disengaged position, the contacting arms can pivot independently with respect to each other, and when the actuator is in its engaged position, the pivoting movement of one contact arm is accompanied by approximately equal pivoting movement of the other contact arm in the opposite direction.