GB2542626A

GB2542626A - Surgical aid

Info

Publication number: GB2542626A
Application number: GB1517096.2A
Authority: GB
Inventors: John Coleman Mark; Che Ho Chan Alfred; Peter Giles Colin
Original assignee: Red Sphere Tech Ltd
Current assignee: Red Sphere Tech Ltd
Priority date: 2015-09-28
Filing date: 2015-09-28
Publication date: 2017-03-29
Also published as: GB201517096D0

Abstract

A device for assisting a surgeon or dentist to maintain alignment of a drilling instrument has an orientation sensing unit mounted on the tool and a means for alerting the user to variations in the orientation. The alerting means can be an audible signal or a graphical display. A display screen may be integral with the sensing unit or separate. The sensors may be one or more of accelerometers, gyroscopes or geomagnetic sensors. The sensing unit may be integral with the tool or removably mounted to it by a mounting ring 8b having troughs on its surface. A reference ring 8a is also mounted to the tool and supports a spring biased ball bearing (43, figure 3) into engagement with the troughs on the mounting ring. The rings permit predetermined variation in the relative angular position of the sensing unit and the tool. A second sensing unit may be located on the patient, being incorporated into a bite block.

Description

Surgical Aid

This invention relates to a surgical aid. In particular, but not exclusively, it relates to an aid for implant surgery such as implant surgery used by dental surgeons to fix implants into mouths, or for osteotomy preparation guidance.

The dental drill is one of the most common tools used by a dental surgeon. One of the treatments it is most commonly used for is dental implants. Precision and accuracy is required by the dental surgeon to drill into the required position within the patient's mouth or jaw for the application of the implant and it is vital that the drill be located and positioned accurately, and that accurate positioning is maintained throughout the drilling operation.

Most surgery is carried out by the surgeon's free hands in a 3-dimensional space of the surgical field. This is particular true for dental surgery, especially implant surgery. Automation or robotics systems have been designed but have not replaced the human surgeon when dealing with intra-oral implant placements.

To improve osteotomy accuracy several implant surgery protocols have been designed to transfer 2-D and 3-D information collected pre-operatively (via CT scan/ radiographic systems and special stents based on this data) to the real 3-D surgical site. The information collected on a case -by-case basis is very dependent on complexity of case, justification of exposure to radiation, patient preferences/ consent and costs.

The production and costs of stereolithographic stents with metal tubing in a set axis for drilling via cone-beam CT scans with computer assisted planning of the 'complex' cases (Nobel Guide AII-on-4 system) can be justified to gain accuracy of angulation of implant placement of < 7degrees 88-91% of the time, 0.9mm entry point and 1.0mm osteotomy apex positional differences when compared to computer-planned positions. [Sarment DP et al.: Accuracy of implant placement with a stereolithographic surgical guide. Int J Oral Maxillofac implants 2003; 18:571-577]

All the hard tissue navigation and tracking systems in existence that are clinically trialed and marketed rely on CT scanning information i.e. image guided surgery.

However the majority of general practice implant cases are relatively straightforward, particularly if implant surgery is only part of a surgeon's restorative general practice, or the surgeon has just started to carry out implant surgical therapies either as an undergraduate or on a post-graduate programme.

In such cases the use of 'specialist' radiographic imaging protocols, systems and subsequent radiation exposure of patient and added costs to an already expensive procedure can be difficult to justify.

Due to the cramped nature of the surgical area within the oral cavity, visualizing the 3-D dimensional position and relationship of the drill head and extrapolation of the hidden osteotomy drill piece tip is difficult.

There is also a bias of the arc of the hand movement especially when resting on a solid surface to pivot on. This tends to produce an elliptical hole rather than a linear osteotomy that will cause deviation away from the intended ideal implant fixture placement position.

Usually the entrance at bone ridge level is fairly accurate to the planned entry point (via visual check and use of a standard implant surgical stent made on patient pre-op plaster models with diagnostic wax-up of planned restorations), however the osteotomy apical position may have deviated from the planned position.

Studies have shown average differences of 2.1mm difference from the planned 'ideal' position by experienced operators. [Esposito M et al.: Biological factors contributing to failures of osseointegrated oral implants. (II) Success criteria and epidemiology. Eur J Oral Sci 1998; 106:527-551.] This may affect the primary stability of the implant placement and also will have a consequence to the alignment of the implant fixture to the proposed prosthetic plan and resultant aesthetics. These particular problems can lead to 'failure' of the implant therapy.

The present invention arose in an attempt to provide an aid to assist a surgeon in such surgery, but is applicable for many types of surgery on different parts of the body.

The proposed invention is an attachable module with gyroscopic or accelerometer technology with inclination or tilt-sensing capabilities.

The module may be linked to a processor unit (similar to an apex locator system) which produces a radar-like, dot in circle or target-type display / graphic either on the unit attached to the head of the handpiece and/or on the display of the side unit (as with an apex locator) with or without an audible sound.

According to the present invention in a further aspect there is provided apparatus for assisting a surgeon to maintain alignment of a surgical instrument, comprising an orientation sensor arranged to measure the orientation of the instrument during an operation, and means for alerting a user if the orientation varies.

The apparatus may be a module attachable to a dental drill. It may be attached to the drill (preferably on its dorsal surface) or to the drill engine housing.

The means for altering a user may be a display and/or audible means.

Preferably, the apparatus comprises sensor means and a display mounted in a housing which is located on the instrument so as to move and alter its disposition as the instrument is moved. This may be removably attachable to the instrument or may be integral herewith.

The sensor means may comprise one or more of an acceleration sensor, a gyroscope and a geomagnetic sensor and/or other sensors. It may be configured as a chip or integrated circuit combining two or more of these sensors, together with sensor algorithms.

The orientation sensor may include a display and a mechanism may be provided whereby the relative angular positions of the orientation sensor apparatus, and an instrument on which it is mounted may be varied in order to provide for different viewing requirements for a user.

Preferably the apparatus includes a further device which is positioned on or mounted to a patient and which can provide an indication of the orientation of the part of the patient being operated on, and means for using information from this, together with information relating to the orientation of the instrument, to provide enhanced accuracy and position sensing.

This further apparatus may comprise a bite block or other device adapted to be positioned inside a patient's mouth and including means for sensing the attitude of the bite block or other means and for transmitting this to a processor which also receives data associated with the attitude of the instrument.

The invention can provide micro-osteotomy guidance for implant surgery, particular dental implant surgery. It may provide a first device for determining the attitude/orientation of a surgical instrument such as a dental drill, a second device for determining the attitude/orientation of the part of a patient being operated upon by the instrument and a processing means, which may be remote from both these devices. Displays may be provided upon any device. A display on the apparatus mounted on a surgical instrument may provide means of showing in an easily graphically viewed manner whether the attitude of the instrument is varying beyond a threshold. It may for example have a display which has a part which is coloured, say, green and which turns red if the attitude, say the roll, alters by a predetermined amount, say 2 degrees.

The display may be radar-display like, ie a spot movable within a circle to indicate deviation in any direction, or a target-type display.

The invention provides an attachable module having gyroscope and/or acceleration sensor capacity with inclination/tilt sensing capacity.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which;

The device may be seen as a 3-D split level/plumb line.

Figure 1 shows systematically a dental drill and apparatus for measuring and displaying the attitude/orientation of the drill;

Figure 2 shows the orientation determines apparatus;

Figure 3 shows the orientation determines apparatus, partially in cross-section;

Figure 4 shows part of the orientation apparatus;

Figure 5 shows a clamp;

Figure 6 shows parts of an orientation apparatus.

Referring to Figure 1, there is shown systematically a dental drill, having a head 1 and a body 2. It is driven by a motor 3 which may be connected to a control unit 4 by means of a cable 5.

In surgery such as implant surgery it is important that the head and drill bit is position very accurately and that the hole drilled is as accurate as possible. If the drill is allowed to rotate, for example, about the longitudinal axis of its handle, or to otherwise shift in attitude/orientation such as in yaw, pitch or rolling, then this can create a poor quality hole, damage healthy tissue or have other disadvantageous effects. The present invention therefore provides an apparatus for determining the orientation and for providing feedback to the user if the drill starts to move away from a pre-determined orientation.

In the embodiment shown in Figure 1 this comprises a sensing apparatus 6 which is removeably attachable to the handle part 2 of the drill. The sensing apparatus comprises a housing, one or more orientation sensing devices, as will be further described below, and an attachment means 8 (comprising two parts 8a and 8b) as will be further described below) and which is adapted to attach the orientation device removably to a drill handle. The orientation device includes a display 9 for displaying orientation, or changes in orientation, to a user and can be preferably positioned relative to the drill handle in a number of positions for convenient viewing by a user such as a dental surgeon using a drill. The housing is connected by means of cable 10 for example to a control unit 11 which in itself may include a display 12. The control unit may be a computer.

The apparatus is therefore, in this embodiment, an attachable module with orientation sensing (eg gyroscopic or accelerometer) with inclination or tilt-sensing properties.

In a modification a further orientation device but this time adapted to measure the orientation of a body, or at least a part of a body operated on by the instrument such as the drill, is included. For dental purposes, this may comprise a bite block 15 which is shown very schematically in the figure. By placing this within a patient's mouth and asking them to bite down on it then clearly the attitude or orientation of this will move as the orientation of the patient's head changes. This will generally be positioned in the other side of the mouth to that which is being drilled. In embodiments, the bite block includes one or more attitude/orientation sensors and is connected by, cable or otherwise 16 to the control unit 11. The control unit can then use suitable software, firmware and/or hardware to compare singles from apparatus 7 and the bite block 15 in order to provide a representation of the orientation of the drill relative to the orientation of the mouth and therefore provide improved results.

Figure 6 shows the main components of the sensor apparatus 6. This comprises a housing 7 which is typically of a plastics material. Provided within this is a position sensor 20 which may be a single chip as is commercial available. It is typically an intelligent 9 "axis absolute orientation sensor". Preferably it includes a variety of sensors but embodiments may include only one or two sensors. In the embodiment shown in Figure 6 it includes an acceleration sensor 21, a gyroscope 22, and a geomagnetic sensor 23. Between them, the absolute orientation of the sensor 6 can be determined. They link to a means 27 providing sensor algorithms, such as fusion algorithms as are known generally in the art, and which can process data from the various position sensors in order to determine the absolute or relative orientation of the device.

The chip 20 may be of the type that is commercially used in, for example, mobile phones and may, for example, be a Bosch BMI055 6 - axis sensor, or a BMX055 9 - axis sensor.

The sensor may also include a power supply 24, a processor/controller 25 and a display (26). It also includes a data or single input/output 28 for connecting to a cable for passing signales to and from the controller 11 for example. This will be a socket. This sensor may alternatively receive power from the controller.

The display, which may be an OLED display, can display the relative or absolute orientation of the device. It may however simply be used to indicate changes in orientation of the device. For example, it may have a mode which presents the green display and which turns, say, red if the orientation changes by more than a predetermined amount by roll, pitch or yaw for example. In this case, a surgeon can immediately tell if his drill is moving out of alignment. It may alternatively or in addition include absolute values such as numbers or many other details. It may be adapted to display arrows indicating the opposite of the way in which the device has moved. Thus, referring to Figures 1 and 6, if the drill rolls clockwise about its axis in Figure 1 then the display may be adapted to show an arrow either in a clockwise direction or possibly more intuitively, to show an arrow in the counter clockwise direction (ie in the direction from the top of the figure downwards in Figure 6) indicating the direction in which the operator must roll the drill back in order to re-align the drill. Many other display options will be apparent.

Figure 2 shows the sensor device in a little more detail. This shows the housing 7 and, in this case, an integrated cable 10 leading to a control unit. The figure shows in more detail one method by which the device may be attached to a dental drill or other surgical instrument. At the other end of the housing is provided a generally arcuate fixing ring 30 of size adapted to mount around a drill handle (so typically around 20mm + 5 mm diameter (although this may vary). This extends outwardly from the plane of the housing as shown. Preferably, it is discontinuous and a clamp mechanism (shown in Figure 5) is used to clamp the device 6 to the handle. Thus, the ring may be formed of two generally semi-circular parts which are hinged together towards the top and at the bottom at the end of one of the parts 30a a clamp mechanism 32 is provided. This comprises a first member 32 which is pivotally attached at one end 32a to the end of part 30a and a second member 33 which is pivotally attached a distance from the pivoted end 32a of member 32 but preferably nearer this end than its other end. This includes a hole or slot (not shown) towards its distal end away from the pivot point 34. A hook 35 mounted towards the end of the other end 30b of ring 30 and is adapted to locate within the slot by pulling back on the distal end 32b of member 32 in the direction of arrow A, so that 30 the two parts 30a and 30b are drawn together. This is a typical conventional clamping mechanism used for many purposes and will be well known to those skilled in the art. Other clamping mechanisms may be used. Instead of a hole the hook 35 may fit in a slot or other means and may not necessarily be hook shaped, it could simply be a protrusion.

Whilst a single ring 30 may be used, in preferred embodiments a second ring 40 is also provided (shown as 8a in Figure 1 where the first ring is shown as 8b). It is essentially a ring without a connected housing and also includes a similar clamp mechanism 42. This ring may be separately attached to a handle and then the two rings 30 and 40 connected together by an appropriate mechanism that, most preferably, enables the relative dispositions of the two rings to be altered by a user. By controlling the relative angular position, the location of the sensor of the device 6 relative to the handle may be altered so that a surgeon may place the device at an appropriate position such as when he is using the drill he can easily view it. The user may prefer it not to lie directly on top of the handle but to lie rotated to a certain degree.

In the embodiment shown this is achievable by a mechanism which can place the two parts in a number of discreet relatively rotated positions. As shown in Figure 3, in one example, ring 40 may include a bearing in the form of ball bearing 43 which is sprung loaded by a spring 44. The bearing 43 is provided at a side, at the top of the ring, and the spring extends from the bearing towards the other side 45. By ensuring the spring is under tension, it tends to push the bearing outwards and if the bearing is pushed inwards, in the direction towards end 45, then when pressure is released the bearing will be forced outwards to the right in the figure. Spring 44 may be mounted upon a member 46 in some embodiments.

The corresponding edge of ring 30 includes an undulated cam surface 50 having peaks 51 and troughs 52. Each trough is of sufficient diameter to receive the bearing 43. Thus, the bearing can be located in any one of the various troughs 52. The relative angular positions of the rings can then be altered by, for example, keeping one of the rings stationary and rotating the other ring which will cause the bearing 43 to act against the undulating cam surface 50 to locate inside an adjacent slot 52. Thus, once in a slot, the two parts are relatively rigidly combined and inadvertent changing of the angular disposition of the device is avoided unless deliberate force is used to rotate it. By using a printed numerical scale of minus 4 through zero and plus 4 (for example) around the rim of the ring, the bearing 42 can be located into an appropriate slot corresponding to any of the positions from minus 4 to plus 4 and thus the relative position be selected. The printed range is shown more clearly in Figure 4. Of course more or less than 9 relative rotational positions (-4, -3, -1, 0,1, 2, 3, 4) may be used.

Hence, in the same way that a user may prefer to wear a watch such that the face is at a particular angular position relative to the wrist, so by using embodiments such as that of Figure 2, the position of the sensor device 6 relative to the drill or other surgical instrument can be chosen for the user's convenience.

The device can be attached by other means, such as by adhesive means (eg double-sided adhesive gel pads, or straps, for example. A device or module may be attached to a drill itself, or drill-head, or to a drill engine housing.

Figure 1 also shows an alternative feature in which, in addition to the sensor unit 6 a further sensor unit 15 is used which provides an indication of the orientation/attitude of the part of the patient itself that is being operated on (typically the jaw).

In a preferred embodiment, this may comprise a bite block which includes one or more sensors within it and which is intended to be placed within a patient's mouth when they are being operated on by a dental surgeon. Bite blocks themselves are well known and, typically, a bite block may be placed on the opposite of the mouth to the part being operated on, so that the patient bites down on the bite block. In embodiments the bite block includes one or more sensors of the type described with reference to the mains sensor unit, such as an acceleration sensor, a gyroscope, a geomagnetic sensor or other sensors and preferably also some intelligence in the form of processor algorithms. It is connected by a wire or wireless single to the main control unit 11. Note also in passing that the main sensor unit 6 may also be connected wirelessly to the control unit 11 rather than by wires as shown. The bite block will then of course alter it orientation as the patient alters the orientation of their mouth and jaw area and therefore provide a signal associated with this. By knowing both the orientation of the patient's mouth and also the orientation of the drill or other instrument, the surgeon can gain a better idea of orientation and more accurately position their drill.

Embodiments of the invention are particularly useful for training purposes. A convenient way to describe the function of a device according to the invention is that it is a 3-D spirit level and plumb-line-in-one.

The patient's head will preferably be kept stable with a simple memory foam head and neck support rest with adjustable 'sides' to hold the head in place.

The device may provide 'live' feedback to the surgeon of their ability to stay 'online' to their chosen direction of osteotomy preparation in 3-dimensions (3 planes- mesio-distally, buccal- lingually/palatally and vertically.

The surgeon, with or without surgical stent, may set the desired path of angulation for osteotomy with a 2mm twist or pilot drill. This inclination is set with a button/switch and any deviation of inclination of drill head will inform surgeon of changes via acoustic target (sound)/ small 'target' screen/ LED lighting range/line or on a small screen on a remote top module.

Also the 3-D "spirit level" information can inform the operator of where the hidden/buried cutting 'tip' of the drill is likely to be in relation to the 'visible' drill head during preparation of osteotomy. With the pilot hole created then one can continue with the osteotomy protocol with the device to re-confirm desired angulation throughout. This will also help with operator posture as they will not need to keep rechecking visually in all 3 planes during osteotomy preparation, the movement of doing so is likely to change angulation of handpiece and drill tip during this critical stage of the preparation.

The operating unit or console may be a standalone pc or may be a separate device which is in itself connectable to a pc or other computer. It may comprise a housing made of plastic, for example, which can house a mother board, a graphical user interface or provided it is on display 12, various other boards and a power supply such as batteries. It may also comprise (not shown for clarity) one or more power connectors, sensor connectors, perhaps a connector for a foot switch and a power switch. The motherboard within it will typically be fitted with power management circuitry and may be powered by DC or AC. Although in some embodiments the sensor units may have their own power supply, in other embodiments the control unit may provide the power and thus no separate power source is needed in the sensor devices. A control unit may also include battery charging circuitry. A graphical user interface on the control unit can allow users to interact with the device to graphical eye console visual indicators for example. The display 12 is typically a colour touch screen device and can provide user controlling in graphical format and a secondary graphical display representative of the orientation or attitude of the sensor device 6. This can again be useful teaching students, such that a student can view a display on the device whilst a trainer may view a larger display on the control unit. The user can set up a programme which can also be done via the control unit 11.

The control unit can also use a plug in FPGA daughter board providing computational functionality, sensor communication, GUI communication as well as internal power supply and battery charge monitoring. It may be connected by USB or other means, wired or wireless, to a personal computer.

The display 9 on the sensor unit 6 may be arranged to give visual colour messaging to the user indicating duel position status. Some example are given above, but in other example, it may have a display that or part of the display that is coloured blue to indicate "ZEROING". Green to indicate "GO" and red to indicate "OUTSIDE LIMITS". As the positional area increases the colours may change in intensity or saturation or in other ways and the threshold and sensitivity may be adjusted from the console unit 11.

By linking to a control unit, or power on/off apparatus of the drill itself, an 'autostop' feature may be provided, in which once movement is considered unacceptable (out of a desired range) then the drill is stopped.

The bite block 15 in effect provides a second reference sensor channel and this will locked, as described, to the patients upper and lower jaws so that any movement in the patient can be accounted for in the display output 9 of the primary sensor, so that absolute positioning of the drill is maintained.

In some embodiments, the sensor unit 6 may be zeroed pivot to operation, perhaps by pressing a particular button, or touch button on the console display 12 or by, for example, operating a foot operated mechanical switch (not shown). Thus, once the drill has been positioned at the start of an operation this orientation can be used as a zero and then changes from this can be monitored.

The embodiments described above show the sensor 6 as a separate unit which can be attached to any drill or instrument. In other embodiments the sensor unit may be an integral part of a surgical instrument such as a dental drill and form part of the housing or body of these.

The display may be provided remotely from the sensing device. It may be provided on a remote display device. It may be provided on a remote display screen. It may be provided on a face mask or visor worn by the surgeon, either directly or as a "head-up-display" so that the surgeon can view the display attitude, without having to look away from the site he or she is operating on.

In other embodiments the orientation sensor apparatus may be connected to a controller for a drill or other surgical instrument and used to adjust and control the movements of the instrument directly, by providing feedback signals to motors or other apparatus controlling movement of the instrument.

Embodiments of the invention have particular use in dental implant surgery, or other surgery involving drilling into the human jaw, but can be used with other surgery, for example, surgery into which a human or animal bone is drilled into.

Advantageously, a device embodying the invention may be able to detect vibration signatures and therefore provide, via suitable software, indication of bone hardness to the surgeon.

Claims

1. Apparatus for assisting a surgeon to maintain alignment of a surgical drilling instrument, comprising an orientation sensor mounted on the instrument and adapted to measure the orientation of the instrument during an operation, and means for alerting a user to variations in the orientation.

2. Apparatus claimed in claim 1 wherein the altering means comprising a display and/or audible means.

3. Apparatus claimed in claim 1 comprising sensor means and a display, both mounted in a housing which is located on the instrument.

4. Apparatus as claimed in claim 3 wherein the apparatus is removably attachable to the instrument.

5. Apparatus as claimed in any preceding claims wherein the sensor means comprises one or more of an acceleration sensor, a gyroscope and a geomagnetic sensor.

6. Apparatus as claimed in any preceding claim which is removably mounted on a surgical instrument, for example a dental drill.

7. Apparatus as claimed in any proceeding claim, wherein the orientation sensor is mounted on a drill, or drill engine housing.

8. Apparatus as claimed in any preceding claim, wherein the relative angular position of the orientation sensor and the instrument upon which it is mounted, is variable in order for the user to position the sensor apparatus as desired.

9. Apparatus as claimed in claim 8 wherein the orientation sensor includes a first mounting ring, and further comprising a second mounting ring, the two mounting rings being connected together by a spring loaded bearing on one of the mounted rings which locates into a cam surface on the other mounting ring in any of a number of discreet angular positions, so as to alter the relative angular dispositions of the first and second mounting rings and thereby the sensing apparatus.

10. Apparatus claimed in claim 9 wherein the bearing is a ball bearing acted upon by a spring.

11. Apparatus as claimed in claims 9 orlO wherein the ball bearing locates into one of the plurality of troughs on an undulating surface.

12. Apparatus as claimed in any preceding claim including a further sensing device adapted to be mountable to or positioned on a patient and thereby provide an indication of the orientation of the part of the patient being operated on.

13. Apparatus as claimed in claim 12 further including means for using information from both the device attached to an instrument and also the device attached to the body, to provide orientation information to a user of the surgical instrument.

14. Apparatus as claimed in claim 12 or 13 wherein the further device is a bite block.

15. Apparatus as claimed in any preceding claim comprising an orientation sensor integral with a surgical instrument.

16. Apparatus as claimed in any preceding claim wherein the display provides an indication to the user of the direction they must move the instrument to return it to a desired state.

17. Apparatus as claimed in any preceding claim comprising means for setting a zero point at the start of the use.

18. Apparatus as claimed in any proceeding claim, comprising a dental drill and the alignment assistance apparatus forming part of, or removably attachable to, the dental drill.

19. Apparatus hereinbefore described with reference to, and illustrated by, any of the accompanying drawings.

20. A method of maintaining alignment of a surgical drilling instrument comprising mounting at least the orientation sensor of a device as claimed in any proceeding claim on the surgical instrument and using variation in sensed orientation to maintain alignment during an operation or the preparation for an operation.

21. A method as claimed in claim 20 wherein the surgical instrument is a dental drill.

22. A method of maintaining alignment of a surgical instrument, substantially as hereinbefore described with reference to the accompanying drawings.

23. Micro-osteotomy guidance apparatus comprising a first device for determining the orientation of a surgical instrument, a second device for determining the orientation of the part of a patient being operated upon by the instrument, and processing means for determining the orientation, or changes in orientation of the instrument and presenting this to a user.