Radley Scientific Limited

Sean Martin Badcott

Stephen Michael Radley Young

Michael John Radley Young

A series of surgical tools () have respective operative heads (&) mounted adjacent a distal end of an elongate waveguide (). The operative heads (&) are used to remove PMMA bone cement () from within a hollow bone (), such as a femur (), as part of a prosthesis revision operation, such as replacement of an artificial hip joint. Torsional-mode ultrasonic vibrations are transmitted along the waveguide () to the respective operative heads (&), which are applied to the bone cement (), softening it and facilitating its removal. Elongate radial channels () extend across cement-contacting faces of several of the surgical tools (), acting to focus and transmit the torsional-mode ultrasonic vibrations into adjacent cement (). In another tool (), scalloped recesses () in its cement-contact face have substantially the same effect, while in a further tool (), a series of notches () along a distal edge () of the tool () have an analogous function. The operative heads () of certain tools () can be embedded into a cement plug () then used to pull the plug () as a unit out of the bone ().

Orthopaedic cement removal tools and method

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.

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Paignton, United Kingdom

Sean Martin Badcott