Abstract: A knee joint prosthesis which comprises a tibial component (4, 6) and a femoral component (2). The femoral component has condyles (14, 16) which act against the tibial component, directly or indirectly, during flexing of the knee. A cam (20) on the femoral component acts against a post (26) on the tibial component at high flex angles. The surface of the post which is contacted by the cam at high flex angles is convex when the post viewed generally perpendicular to the tibial bone contact and bearing surfaces, and the femoral bearing surface which is provided by the cam, where it contacts the convex surface of the post at high flex angles, is locally concave (32) when viewed along the surface of the post which contacts the cam so that the area of contact between the post and the cam is greater at high flex angles than at lower flex angles.

Abstract: A knee joint prosthesis which comprises a tibial component (4, 6) and a femoral component (2). The femoral component has condyles (14, 16) which act against the tibial component, directly or indirectly, during flexing of the knee. A cam (20) on the femoral component acts against a post (26) on the tibial component at high flex angles. The surface of the post which is contacted by the cam at high flex angles is convex when the post viewed generally perpendicular to the tibial bone contact and bearing surfaces, and the femoral bearing surface which is provided by the cam, where it contacts the convex surface of the post at high flex angles, is locally concave (32) when viewed along the surface of the post which contacts the cam so that the area of contact between the post and the cam is greater at high flex angles than at lower flex angles.

Abstract: A knee joint prosthesis which comprises a tibial component (4, 6) and a femoral component (2). The femoral component has condyles (14, 16) which act against the tibial component, directly or indirectly, during flexing of the knee. A cam (20) on the femoral component acts against a post (26) on the tibial component at high flex angles. The surface of the post which is contacted by the cam at high flex angles is convex when the post viewed generally perpendicular to the tibial bone contact and bearing surfaces, and the femoral bearing surface which is provided by the cam, where it contacts the convex surface of the post at high flex angles, is locally concave (32) when viewed along the surface of the post which contacts the cam so that the area of contact between the post and the cam is greater at high flex angles than at lower flex angles.

Abstract: A knee joint prosthesis which comprises a tibial component (4, 6) and a femoral component (2). The femoral component has condyles (14, 16) which act against the tibial component, directly or indirectly, during flexing of the knee. A cam (20) on the femoral component acts against a post (26) on the tibial component at high flex angles. The surface of the post which is contacted by the cam at high flex angles is convex when the post viewed generally perpendicular to the tibial bone contact and bearing surfaces, and the femoral bearing surface which is provided by the cam, where it contacts the convex surface of the post at high flex angles, is locally concave (32) when viewed along the surface of the post which contacts the cam so that the area of contact between the post and the cam is greater at high flex angles than at lower flex angles.

Abstract: A knee joint prosthesis which comprises a tibial component (4, 6) and a femoral component (2). The femoral component has condyles (14, 16) which act against the tibial component, directly or indirectly, during flexing of the knee. A cam (20) on the femoral component acts against a post (26) on the tibial component at high flex angles. The surface of the post which is contacted by the cam at high flex angles is convex when the post viewed generally perpendicular to the tibial bone contact and bearing surfaces, and the femoral bearing surface which is provided by the cam, where it contacts the convex surface of the post at high flex angles, is locally concave (32) when viewed along the surface of the post which contacts the cam so that the area of contact between the post and the cam is greater at high flex angles than at lower flex angles.

Abstract: A patellar resection tool has first and second gripping members adapted for relative movement between a closed position in which the patella can be held between the gripping members and an open position in which the patella can be released. The tool also has first and second handle members connected to the first and second gripping members respectively, for moving the gripping members between the open and closed positions. The first and second handle members are constrained for relative movement in a first plane and the first and second gripping members are constrained for relative movement in a second plane which is not parallel to the first plane. This allows the tool to be used in a minimally invasive surgical technique in which a patella is everted by an angle less than 90° without obstructing access to the patella.

Abstract: A knee joint prosthesis which comprises a tibial component (4, 6) and a femoral component (2). The femoral component has condyles (14, 16) which act against the tibial component, directly or indirectly, during flexing of the knee. A cam (20) on the femoral component acts against a post (26) on the tibial component at high flex angles. The surface of the post which is contacted by the cam at high flex angles is convex when the post viewed generally perpendicular to the tibial bone contact and bearing surfaces, and the femoral bearing surface which is provided by the cam, where it contacts the convex surface of the post at high flex angles, is locally concave (32) when viewed along the surface of the post which contacts the cam so that the area of contact between the post and the cam is greater at high flex angles than at lower flex angles.

Abstract: A collapsable reamer assembly and method of reaming a cavity into a bone are described. The reamer assembly comprises a base having a housing and an underside presented toward a surface of the bone in use. A collapsable reamer is rotatably mounted in the housing for rotation about a reaming axis directed away from the underside of the base. The collapsable reamer comprises at least one reaming component, supported for movement along the reaming axis from a collapsed state of the reamer to an extended state of the reamer to ream at least partially along the axis into the bone.

Abstract: Apparatus for guiding a cutting tool in a surgical procedure on a bone. The apparatus includes a fixation block which can be fitted on to a bone, a guide block which can be fitted on to the fixation block, and a worm drive assembly for adjusting the orientation of the guide block rotationally relative to the fixation block about the said pivot axis. The guide block defines a path for a cutting tool, in which (i) the guide block can be translated relative to the fixation block along a translation axis so as to vary the distance between the guide block and the fixation block, and (ii) the orientation of the guide block relative to the fixation block can be adjusted lo rotationally about a pivot axis which is approximately perpendicular to the translation axis.

Abstract: A patellar resection tool has first and second gripping members adapted for relative movement between a closed position in which the patella can be held between the gripping members and an open position in which the patella can be released. The tool also has first and second handle members connected to the first and second gripping members respectively, for moving the gripping members between the open and closed positions. The first and second handle members are constrained for relative movement in a first plane and the first and second gripping members are constrained for relative movement in a second plane which is not parallel to the first plane. This allows the tool to be used in a minimally invasive surgical technique in which a patella is everted by an angle less than 90° without obstructing access to the patella.

Abstract: A vent valve for an air braking system of a vehicle comprises an elastomeric valve member (11) held in relation to a vent (17) and having a restricted vent passageway. A continuous depending rib (23) is engageable with a valve seat (28) to close the vent passageway as increasing pressure acts on the head (21) of the valve member (11). The valve member (11) permits a fluid chamber to be connected to exhaust until pressure in the chamber reaches a predetermined level.