Sra Developments Limited

Other

Radley Scientific Limited

Stephen Michael Radley Young

Michael John Radley Young

Michael James Ede

James Anton Slipszenko

Sean Martin Badcott

Neil Christopher Pearse

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.

Torsional ultrasound generator for orthopaedic procedures

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.

Torsional orthopaedic revision system

A transducer stack () includes rings () of piezo-electric ceramic alternating with metal electrodes () along a threaded central shaft () extending from a titanium back plate (). A spacer or threaded element () threaded on to the shaft () holds the ceramic rings () and electrodes () in compression against the back plate (). The transducer stack () is mountable eccentrically to a horn () of an ultrasonically-vibratable tool, away from an axis of an elongate waveguide () extending from the horn (). The transducer stack () may vibrate in a flexural mode perpendicular to the waveguide (), generating torsional mode ultrasonic vibrations in the horn () and waveguide (), or in a flexural mode parallel to the waveguide (), generating longitudinal mode ultrasonic vibrations in the horn () and waveguide (). The transducer stack () may be tuned by adjusting the length, mass and/or position along the shaft () of the threaded element (), the back plate () and/or a second threaded element () mounted to the back plate (). Motion sensors () may be mounted to the horn (). Torsional vibrational modes of the horn () and waveguide () may be identified by motion amplitude of a peripheral sensor () exceeding that of a near-axial sensor (). The operation of the transducer stack () may be controlled in response thereto.

Ultrasonic transducer system

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.

Ultrasonic cutting tool

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

Ultrasonic surgical tool

At the surgical tool's proximal end, there is a first means () to generate ultrasonic vibration in a torsional shear mode. There is also a second means () to generate ultrasonic vibration in a longitudinal compression mode. A wave guide () is operatively connected to both generating means and extending therefrom by a distance of n&#x3bb;/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, &#x3bb;c: &#x3bb;&#x3c4;, is an odd number. Preferably &#x3bb;c=N&#x3bb;&#x3c4; (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.

Apparatus () for generating torsional-mode ultrasonic vibrations comprises a stack of axially-polarized piezo-electric ceramic rings () having a torsional converter () mounted coaxially to either one face of the stack or to two opposite faces thereof. Each torsional converter () has a cross-sectional inhomogeneity comprising a plurality of helically-extending grooves () extending substantially from end to end of the converter. The grooves () each have a length, measured axially along the converter (), of approximately half the wavelength of ultrasonic vibrations therein. When the stack is energized, the stack and the converter () or converters () resonate together in a purely torsional-mode vibration. The apparatus () 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 () of a tool to a distal operative tip (). A very high amplitude torsional oscillation may thus be induced at the operative tip () of the tool. Alternatively, a further converter element () may be located at a distal end of the waveguide () in order partially to convert torsional-mode to longitudinal-mode vibrations for tool operative tips requiring combined-mode oscillations.

Torsional mode ultrasonic generator

An ultrasonic surgical tool has an elongate waveguide operatively connected or connectable to a source of ultrasonic vibrations. An operative element at a distal end of the waveguide has a diameter less than that of the waveguide. A connecting portion of intermediate diameter may connect the operative element and the waveguide. A proximal end of the operative element forms a first step junction, located at a nodal plane of ultrasonic vibrations in the waveguide and operative element, producing a velocity amplitude gain across the step junction. A second zero-gain step junction between the connecting portion and the waveguide is located at an anti-nodal plane. The operative element may include a curved distal cutting and welding element having a pair of elongate welding grooves defining a cutting edge. Alternatively, the operative element may include a welding element having a flat or slightly ridged operative face.

Ultrasonic tissue dissector

Ultrasonic generator

A switch unit () is mountable to a distal end of a handpiece of an electrically-activatable surgical tool, such as an ultrasonically-vibratable surgical tool. The switch unit () has a generally bullet-shaped outer form with an axial bore () through which a waveguide of the tool extends. A resiliently deformable band () extends around the switch unit () above a polygonal-section contact zone (), such that fingertip pressure on the band () may locally depress the band () towards a flat area () of the contact zone (). Switch contacts () are mounted to an inner surface of the band () opposite a plated circuit () located on each flat area () so as to form a plurality of switches. A switch to activate the tool is thus easily accessible to a user's fingertip in any orientation of the handpiece in the user's hand. The switch contacts () may each comprise a body having an electrical resistance dependent on a pressure exerted thereon. A magnitude of a response from the tool may thus be controlled by the pressure exerted by the user's fingertip.

Switch for ultrasonic surgical tool

The system generates resonant ultrasonic vibrations, preferably in a torsional mode. A control circuit monitors, feedback signals therefrom, which are scanned to determine the frequency at which minima occur. The frequency of the ultrasonic signal is then adjusted to the frequency at which the minimum occurs.

Ultrasonic generator system

The apparatus comprises an ultrasonic vibration generator () and a lens () affixed thereto adapted to focus the ultrasonic vibration at a predetermined zone. It may be used to destroy certain types of cancerous cell which lie close beneath the surface, such as skin cancers and other melanomas. Other cosmetic skin treatments may also be carried out, such as restructuring collagen molecules in order to tighten and restructure skin tissue, depilation and to destroy dyed tissue and thereby aid removal of unwanted tattoos.

Method and apparatus for focussing ultrasonic energy

The system controls the frequency of an ultrasonic signal to be applied to a waveguide, such that the frequency corresponds to a preferred resonance mode of the waveguide and not to adjacent undesirable resonance modes. The system operates by carrying out a first scan of a predetermined portion of the generated signal, determining the number of resonance modes of the waveguide within this portion and selecting from these resonance modes either that one mode which is at a central frequency or that one mode which is at a frequency nearest thereto. The system may also set limits on each side of the selected resonance mode and carry out a second scan within these limits each time that the generator is activated to check whether the selected resonance mode is drifting.

The mechanism is applicable to a surgical tool which has a jaw () pivotably mounted to a distal end of a longitudinally extending support (). The jaw is operated by action on a rearwardly facing cam follower () by a lobe () on the distal end of an actuating tube (). Rotation of the actuating tube () causes pivoting of the jaw () into and out of operative relationship with another jaw member () of the tool. The mechanism may be applied to any manipulative or gripping type of surgical implement, but is particularly applicable to ultrasonic tools adapted for cutting and/or coagulating.

Growing community of inventors

South Devon, United Kingdom

Stephen Michael Radley Young