Abstract: Apparatus for generating torsional-mode ultrasonic vibrations, for example in a surgical tool, comprises an ultrasonic transducer that would conventionally produce longitudinal-mode ultrasonic vibrations, with a long, hollow, cylindrical, mode converter mounted coaxially to its distal end. A plurality of holes are formed through the walls of the mode converters. These holes are arranged in multiple parallel helical rows, extending along and around the cylindrical mode converters. Holes within the same row are spaced relatively closely, compared with the spacing between rows. Relationships have been established between the hole diameter (d), the spacing between rows (W), the spacing between holes in the same row (l), the spacing between individual holes in adjacent rows (L), and the overall diameter of the mode converter (D). In a preferred version, the holes through the walls of the second mode converter are tapered inwardly, rather than being cylindrical holes as in the first mode converter.

Abstract: A fracture in a hollow bone is supported temporarily by a rigid plastics implant formed within a balloon within the bone. To assist implant removal, an access port, comprising a hollow cylinder, is inserted through an aperture made in an end of the bone and surrounds a proximal end of the implant. The access port is connected to a source of torsional-mode ultrasonic vibrations to soften the plastic implant and improve engagement between access port and implant. Removal of the ultrasound source allows introduction of a cutting tool through the access port, which guides it to hollow out the implant. The implant then collapses within the balloon and is withdrawn through the access port. One suitable cutting tool has a head with four helical fins separated by part-circular grooves and a concave distal face. Ultrasonically activated, the fin tips soften and cut the plastic, which flows away along the grooves.

Abstract: Apparatus for generating torsional-mode ultrasonic vibrations, for example in a surgical tool, comprises an ultrasonic transducer that would conventionally produce longitudinal-mode ultrasonic vibrations, with a long, hollow, cylindrical, mode converter mounted coaxially to its distal end. A plurality of holes are formed through the walls of the mode converters. These holes are arranged in multiple parallel helical rows, extending along and around the cylindrical mode converters. Holes within the same row are spaced relatively closely, compared with the spacing between rows. Relationships have been established between the hole diameter (d), the spacing between rows (W), the spacing between holes in the same row (l), the spacing between individual holes in adjacent rows (L), and the overall diameter of the mode converter (D). In a preferred version, the holes through the walls of the second mode converter are tapered inwardly, rather than being cylindrical holes as in the first mode converter.

Abstract: A torsional-mode ultrasonic vibration generator is manufactured with longitudinal slots extending along its horn which damp unwanted vibrational modes and allow it to be made significantly smaller than previous apparatus. The torsional-mode ultrasonic generator is operable with a suite of surgical tools, to perform portions of an orthopaedic arthroplasty revision procedure. Three of the tools are for removing bone cement from within a bone cavity on a prosthesis cemented into the bone cavity. Three other tools are for separating an uncemented prosthesis from ingrown bone by cutting the bone between the prosthesis and walls of the bone cavity. The seventh tool is provided with sensors to determine a separation between a bone-cutting tool head and a metal prosthesis, feedback from the sensors being used to control servo motors of an articulated mounting for the seventh tool, to maintain the separation at a desirable value.

Abstract: A tool (1, 31) for cutting bone comprises an elongate blade (7, 37) connectable to a generator of longitudinal-mode ultrasonic vibrations. The blade (7, 37) has two lateral cutting edges (9, 10) linked by a rounded distal tip (8). A series of triangular teeth (13) extends along each cutting edge (9, 10) and the distal tip (8). The blade (37) may taper towards each cutting edge (9,10) and the distal tip (8). A variant of the tool (21) comprises an elongate part-cylindrical blade (27) connectable to a generator of torsional-mode ultrasonic vibrations. The blade (27) has a cutting edge at its distal tip (28) provided with a plurality of triangular teeth (23). All forms of the tool (1, 21, 31) are particularly suitable for cutting cancellous bone around an implant to be removed during revision of a joint arthroplasty.

Abstract: A fractured hollow bone can be supported by forming a rigid plastics implant within a cavity of the bone, extending across the fracture. An access port aids removal or revision of the implant. The port comprises a hollow cylinder, with a distal end inserted through an aperture in an end of the bone into the cavity to surround a proximal end of the implant. The access port is connectable to a source of torsional-mode ultrasonic vibrations, which soften the plastics material of the implant, improving engagement between the implant and a threaded formation within the distal end of the access port. Removal of the source allows the access port to act as a guide passage, in line with the elongate implant. A cutting tool introduced through the access port is thus guided so that it can be used to hollow out the implant. Once sufficiently hollowed-out, the implant collapses within its surrounding balloon.

Abstract: A torsional-mode ultrasonic vibration generator is manufactured with longitudinal slots extending along its horn which damp unwanted vibrational modes and allow it to be made significantly smaller than previous apparatus. The torsional-mode ultrasonic generator is operable with a suite of surgical tools, to perform portions of an orthopaedic arthroplasty revision procedure. Three of the tools are for removing bone cement from within a bone cavity on a prosthesis cemented into the bone cavity. Three other tools are for separating an uncemented prosthesis from ingrown bone by cutting the bone between the prosthesis and walls of the bone cavity. The seventh tool is provided with sensors to determine a separation between a bone-cutting tool head and a metal prosthesis, feedback from the sensors being used to control servo motors of an articulated mounting for the seventh tool, to maintain the separation at a desirable value.

Abstract: A surgical tool having an elongate shaft, with a directional operative element at its distal end, is provided with a mechanism to rotate the shaft and the operative element about a longitudinal axis shaft. This allows the operative element to be aligned with an element of tissue without excessive hand movement by the user. In a preferred version, the mechanism is electrically powered and is regulated to produce smooth, controlled, accurate motion between selected rotational positions. The mechanism may include a linear magnetic motor drive to move a drive element longitudinally along the tool. This drive element is engaged with a helical formation on a drive shaft, such that longitudinal motion of the drive element is converted to rotational motion of the drive shaft, and of the shaft and operative element, to which the shaft is mounted.

Abstract: A surgical tool having an elongate shaft, with a directional operative element at its distal end, is provided with a mechanism to rotate the shaft and the operative element about a longitudinal axis shaft. This allows the operative element to be aligned with an element of tissue without excessive hand movement by the user. In a preferred version, the mechanism is electrically powered and is regulated to produce smooth, controlled, accurate motion between selected rotational positions. The mechanism may include a linear magnetic motor drive to move a drive element longitudinally along the tool. This drive element is engaged with a helical formation on a drive shaft, such that longitudinal motion of the drive element is converted to rotational motion of the drive shaft, and of the shaft and operative element, to which the shaft is mounted.

Abstract: The ultrasonic surgical tool has an elongate waveguide operatively connected or connectable at a proximal end to a source of ultrasonic vibrations. At a distal end, an operative element comprises a radially-extending ridge defined between a substantially parallel pair of grooves extending longitudinally of the waveguide. The operative element is curved in a plane transverse to that of the ridge. This arrangement is ergonomically superior and allows a surgeon to work for longer and with improved control. It also allows a clear visualization of the operative elements of the tool and the target tissue.

Abstract: The shaped output is for use with an ultrasonic surgical tool vibratable in torsional mode. The output has a generally cylindrical first waveguide (1) with, at a distal end a second waveguide extension member (3) of reduced diameter. The second waveguide (3) is curved in one plane from the axis of the first waveguide. It has at least two blade faces (4) extending radially outwardly from its distal end.

Abstract: An osteotome suitable for cutting through cancellous bone that is holding an orthopaedic implant requiring revision within a cavity of a bone, includes a cylindrical waveguide connectable to a source of ultrasonic vibrations at its proximal end and a blade having a hollow part-cylindrical cross-section and a cutting edge at its distal tip. The respective longitudinal axes of the waveguide and the blade cross at an angle of about 30°, and the waveguide and blade taper and curve smoothly together where they meet. The osteotome is dimensioned such that a first antinode of the ultrasonic vibrations is located at a proximal end of the waveguide, a second antinode is located at the distal tip of the blade and a node is located where the waveguide and blade meet. The osteotome cuts readily through cancellous bone when ultrasonically energized.

Abstract: At the surgical tool's proximal end, there is a first means (3) to generate ultrasonic vibration in a torsional shear mode. There is also a second means (2) to generate ultrasonic vibration in a longitudinal compression mode. A wave guide (4) is operatively connected to both generating means and extending therefrom by a distance of n?/2 to a distal end provided with cutting and/or coagulating means. The ratio of the wavelengths of the longitudinal compression wave and the torsional shear wave, ?c: ??, is an odd number. Preferably ?c=Nx?? (where N is an odd integral number and x is an integer). Delicate shear motion of the torsional ultrasonic vibrational mode is combined with the more vigorous excitation of the longitudinal compression wave ultrasonic vibration.

Abstract: A bone resector tool comprises an ultrasonic transducer, typically generating longitudinal mode vibrations at around 40 kHz, and having an elongate blade portion mounted thereto. The transducer and blade portion are mounted to a rotatably-drivable converter element. Rotation of the converter element produces reciprocal longitudinal motion of the transducer and blade portion. A counterweight is also mounted to the converter element, moving exactly out of phase with the transducer and blade portion, such that a centre of mass of the whole system is stationary, reducing vibration of the tool in a user's hand. The peak velocity due to the ultrasonic vibrations of a distal tip of the blade portion is up to seven times greater than its peak velocity due to the reciprocal longitudinal motion. This permits rapid, low-effort cutting of bone with easy removal of cut debris and minimal consequent necrosis.

Abstract: A tool (1, 31) for cutting bone comprises an elongate blade (7,37) connectable to a generator of longitudinal-mode ultrasonic vibrations. The blade (7,37) has two lateral cutting edges (9,10) linked by a rounded distal tip (8). A series of triangular teeth (13) extends along each cutting edge (9,10) and the distal tip (8). The blade (37) may taper towards each cutting edge (9,10) and the distal tip (8). A variant of the tool (21) comprises an elongate part-cylindrical blade (27) connectable to a generator of torsional-mode ultrasonic vibrations. The blade (27) has a cutting edge at its distal tip (28) provided with a plurality of triangular teeth (23). All forms of the tool (1, 21, 31) are particularly suitable for cutting cancellous bone around an implant to be removed during revision of a joint arthroplasty.

Abstract: A tool (1, 31) for cutting bone comprises an elongate blade (7, 37) connectable to a generator of longitudinal-mode ultrasonic vibrations. The blade (7, 37) has two lateral cutting edges (9, 10) linked by a rounded distal tip (8). A series of triangular teeth (13) extends along each cutting edge (9, 10) and the distal tip (8). The blade (37) may taper towards each cutting edge (9,10) and the distal tip (8). A variant of the tool (21) comprises an elongate part-cylindrical blade (27) connectable to a generator of torsional-mode ultrasonic vibrations. The blade (27) has a cutting edge at its distal tip (28) provided with a plurality of triangular teeth (23). All forms of the tool (1, 21, 31) are particularly suitable for cutting cancellous hone around an implant to be removed during revision of a joint arthroplasty.

Abstract: An apparatus to aid removal of a prosthetic implant cemented into bone that has an adapter to engage a proximal end of the implant, a clamp screw to hold the engaged end to the adapter in good acoustic contact, a generator for torsional or longitudinal mode ultrasonic vibrations and a coupling link to transmit the ultrasonic vibrations to the adapter and thence to the implant, the proximal end of the implant being gripped between a conical tip of the clamp screw and a raised portion of the adapter to avoid damping flexural mode oscillations induced in the implant by making the zone of contact between the adaptor and implant as narrow as possible.

Abstract: Apparatus (5,50) for generating torsional-mode ultrasonic vibrations comprises a stack of axially-polarized piezo-electric ceramic rings (10) having a torsional converter (1,51,53) mounted coaxially to either one face of the stack or to two opposite faces thereof. Each torsional converter (1,51,53) has a cross-sectional inhomogeneity comprising a plurality of helically-extending grooves (2,55) extending substantially from end to end of the converter. The grooves (2,55) each have a length, measured axially along the converter (1,51,53), of approximately half the wavelength of ultrasonic vibrations therein. When the stack is energized, the stack and the converter (1) or converters (51,53) resonate together in a purely torsional-mode vibration. The apparatus (5,50) is compact and axisymmetric, and is straightforward to incorporate into a simple tool handpiece. The ultrasonic vibrations may be transmitted along a conventional elongate waveguide (3) of a tool to a distal operative tip (35).

Abstract: The ultrasonic surgical tool has an elongate waveguide operatively connected or connectable at a proximal end to a source of ultrasonic vibrations. At a distal end, an operative element comprises a radially-extending ridge defined between a substantially parallel pair of grooves extending longitudinally of the waveguide. The operative element is curved in a plane transverse to that of the ridge. This arrangement is ergonomically superior and allows a surgeon to work for longer and with improved control. It also allows a clear visualization of the operative elements of the tool and the target tissue.

Abstract: An osteotome suitable for cutting through cancellous bone that is holding an orthopaedic implant requiring revision within a cavity of a bone, includes a cylindrical waveguide connectable to a source of ultrasonic vibrations at its proximal end and a blade having a hollow part-cylindrical cross-section and a cutting edge at its distal tip. The respective longitudinal axes of the waveguide and the blade cross at an angle of about 30°, and the waveguide and blade taper and curve smoothly together where they meet. The osteotome is dimensioned such that a first antinode of the ultrasonic vibrations is located at a proximal end of the waveguide, a second antinode is located at the distal tip of the blade and a node is located where the waveguide and blade meet. The osteotome cuts readily through cancellous bone when ultrasonically energised.