WO2008031245A2

WO2008031245A2 - Surgical drilling device

Info

Publication number: WO2008031245A2
Application number: PCT/CH2007/000444
Authority: WO
Inventors: Dominik J. HOIGNÉ; Lutz Nolte
Original assignee: Universität Bern
Priority date: 2006-09-14
Filing date: 2007-09-11
Publication date: 2008-03-20
Also published as: WO2008031245A3

Abstract

The invention is directed to an improved drilling device (1) for making of curved canals (10) especially in bones (10) during surgery. The drilling device (1) com- prises a drilling bit (2), a flexible drive shaft (3) laterally guided in a tubular sheath (5) with a constant radius R. The drilling device (1) is designed to be used like a surgical needle.

Description

SURGICAL DRILLING DEVICE

FIELD OF THE INVENTION

The present invention relates to an improved drilling device for surgery, espe- cially for drilling spatially curved canals in hard materials such as bones.

DESCRIPTION OF THE ART

In the field of surgery, it frequently occurs that a hole must be drilled through hard material to enabling the securing of a filamentary member to the bone. Such holes may be necessary, for example, to secure a ligament to a bone, or to immobilize two adjacent bones either temporarily or permanently. The filamentary members used for this purpose may be thread type sutures or may be wire for example.

Devices for drilling curved canals are know from prior art. However, those devices are, as will become evident from the subsequent appraisal, not practical in application or have a very complicated setup. Often a straight through hole may not be suitable for the intended purpose; and furthermore may be difficult or impossible to drill in the desired relation to the member or tissue which is to be secured to the bone. One common approach to solve this problem is to drill two straight holes - one at the entry point and one at the estimated exit point - inter- secting with each other. However, a problem associated with this procedure consists in that a bone is a material difficult to drill since the drills tend to slide such that obtaining an exact intersection may be somewhat difficult. Another problem associated with this technique is that if the angle of the two holes is too acute, the threading of a suture needle or of a wire may be difficult. A further problem consists in high mechanical stress which has an impact on the surrounding material.

Another common approach to solve the problem is the use of medical forceps or needles to directly punch curved holes into the bone. A major handicap of this approach is the high level of manual force that has to be applied. An attempt to facilitate the use of needles has been proposed by Sohn et al. published under WO9747246 where it is described how a needle which preferably includes superelastic material is forced into the bone by an insertion tool. Al- though this attempt in theory seems to have certain advantages, it was found that it is not practical at all.

US4541423 of Forest C. Barber was filed in 1983 and is directed to a drilling apparatus for attachment to a rotary motor. The drilling apparatus includes a flexible shaft confined in an elongated flexible tubular sheath. The sheath is formed from a semi-rigid material which is bendable to a desired curvature at the use site to select the curvature of the drilled hole. A drilling bit is fixed to one end of the flexible shaft, and includes a shank coacting with the distal end of the sheath to rotationally guide the drilling bit. The flexible shaft projects from the sheath at the proximal end so that both components may be secured to a drill- ing motor which is manipulated to guide the sheath while rotating the cutting bit. The relatively bulky and complicated interconnection to the drilling motor results in a draw back during manipulation. The sheath may remain in the drilled hole temporarily as a liner to guide the passage there through of a relatively stiff wire or other filamentary member. The sheath is not sufficiently rigid and therefore deforms when a canal has to be drilled in bony material. A further disadvantage results from the in situ bending of the canal due to the fact that the curvature is often not very accurate such that the sheath might become stuck in the bore canal which renders the whole device unpractical.

US4312337 of Donohue Brian T was filed in 1980 and is directed to a cannula and a thereto rigidly connected scissor-like guide apparatus for use in drilling and wiring fractured bones. The scissor-like handle arms are pivotally joined and have two opposite jaw extensions beyond the pivot point to which a hollow tubular cannula section is mounted on each jaw extension. By closing the handle arms of the scissor-like guide apparatus, the cannula sections meet in inter- locking engagement to provide one continual cannula. The cannula sections are generally arcuate shaped to fit within converging angular holes drilled through the cortex of the bone on each side of the fracture. When the cannula sections are engaged within the medulla of the bone, a wire is fed through the cannula. As described, the cannula and guide apparatus may also be used for drilling holes for the wiring operation. A flexible cable having a drilling bit on one end thereof is inserted through the medial end of one cannula section and secured by a drill clamp to a drill motor. The described device is difficult to apply in non- standard situations because the rigidly interconnected scissor-like guide apparatus does not allow e.g. a side-ways application. A further disadvantage con- sist in that the bulky guide apparatus prevents the application of the device in laparoscopy.

US4751922 (US'922), respectively EP0253526, of Di Pietro et al. was filed in

1986 and is directed to a flexible medullary reamer for shaping the medullary space of bones. The medullary reamer has a flexible shaft. To permit the use of a guide wire, the shaft may be axially bored throughout its length. A cutting head is arranged at the front end and an adaptor at the back end of the shaft, whereby the device can be connect to the a drive mechanism. Due to the lack of lateral support and guidance the device is not suitable for drilling rigid material, especially not for drilling curved canals.

US5122134 (US' 134) of Borzone et al. was filed in 1990 and is assigned to Howmedia, respect. Pfizer Hospital Prod. US'134 discloses a cutting head for a surgical reamer with a leading end for insertion into a bone canal and a trailing end for attachment to a drive shaft similar to the device as described in US'922.

US5720749 (US749) of Rupp Glenn, was filed in 1996 and assigned to Snap on Tech Inc., is directed to a medullary rotational reaming apparatus. The reaming apparatus comprises an elongated, flexible, hollow, tubular shaft formed of a nickel-titanium alloy and having a coupling portion at the opposite ends thereof. Each of a cutter head and a rotational drive coupling element has a hollow tubular coupling shank. The device has in general a similar setup as described in US'922 and US'134. In practical use the device is not suitable for drilling bony material, due to the flexibility and the lack of lateral stabilization and guidance.

US5395188 (US'188) of Charles Bailey et al. was filed in 1993 and is directed to a drilling tool for drilling a curved hole in non-surgical application. The tool includes a curved guide tube for positioning the tube in drilling position against a wall. A flexible shaft extending through the guide tube has a drilling bit on the end adjacent to the outlet end of the tube and a shank on the opposite end engaged in a drill tool chuck. Operation of the drill tool rotates the drill bit and the tube guides and directs the bit to drill a curved or angled hole. The drill bit can be a spade bit, a spiral bit or a ball mill. Application of this device in surgery seams not to be appropriate because it is optimized to machine wood.

US4941466 (US'466) of Jack Romano was filed in 1990 an is directed to a bulky and complicated drilling apparatus for making of curved bores. The device comprises two power driven drill shafts equipped with flexible shaft sections on the distal ends thereof whereby each flexible shaft section has a cutting tip. A semicircular canal shaped drill guide loosely engages each flexible shaft end section and is caused to rotate through an approximate 90° angle as the cutting tips are advanced. The drill guides are pivotally mounted such that when rotated with respect to each other the cutting tips of the associated rotating flexible drill bits meat each other on a semicircular path.

US2005/203508 (US'508) of Mark Bryant et al., was filed in 2005 and is directed to an apparatus for reducing a hip fracture utilizing a minimally invasive procedure, which does not require incision of the quadriceps. A femoral implant achieves intramedullary fixation as well as fixation into the femoral head to allow for the compression needed for a femoral fracture to heal. An alignment is provided to facilitate alignment of instruments used to create a cavity in the bone for reception of the femoral implant and to facilitate size selection of the femoral implant. US'508 discloses a reaming device for making of a curved canal with a curved reamer shaft in which a flexible driveshaft is arranged which allows for transmission of rotary motion to a reamer head to effect reaming into femoral head. The reaming device has a relatively complex setup and is therefore difficult to dismantle. Furthermore the reaming device is designed to be guided by a guide tube. The rear end is interconnected to a drive unit. Due to the setup only a limited functional use is guaranteed. CH610754 (CH754) of Max Ulrich, was filed in 1977 and is directed to a drilling instrument which is used for drilling curved canals in bones. A curved guide tube is secured on a hand piece of the drilling instrument. The guide tube is designed at its front end as a bearing for a drill bit which is driven via a flexible shaft extending in the guide tube. On the other end the flexible shaft is connected to a motor in the hand piece. The guide tube can be detached from the hand piece and the flexible shaft can be separated from the drive element and removed from the guide tube. Thereby it is possible after drilling a canal in a bone to leave the guide tube temporarily in the drilled canal in the manner of an indwelling cannula. One disadvantage consists also here, that the hand piece is relatively bulky and thereby does not allow to use the device in situations where only limited space is available, e.g. in laparoscopy. A further disadvantage consists in that it is not possible to apply large forces e.g. when hard material has to be drilled.

It is therefore an object of the herein disclosed invention to provide a drilling device suitable for making of a curved canal which overcomes the disadvantages of the devices known from prior art.

A further object of the herein disclosed invention is to provide a drilling device for making of a curved canal which has a simple setup easily adoptable to dif- ferent surgical situations.

Still a further object of the herein disclosed invention is to provide a drilling device applicable in situations where only limited space is available, e.g. such as in laparoscopy. SUMMARY OF THE INVENTION

The herein disclosed invention relates to an apparatus for drilling an exact straight canal or a canal of a selected curvature through a hard or soft sub- stance. More particularly to an apparatus for drilling such a hole through bone, e.g. to enable the securing thereto of wires or sutures for example. As it will become obvious from the subsequent description, a drilling device according to the herein disclosed invention convinces not only due to its simplicity and the thereby achieved ease of application also in areas with only limited space avail- able.

A drilling device according to the present invention in general comprises a flexible drive shaft which comprises in operation at its front end a drilling bit and at its rear end an interconnection to a drive device, e.g. a drive motor. For operation the drive shaft is arranged in an at least at the front end (next to the drilling bit) partially rigid, non-bendable sheath, such that it can be securely clamped by a forceps, e.g. a lockable collet. The sheath in general has a toroidal tubular shape extending about a certain angle, such as 90°, 120° or 180° (other angles are possible) and is preferably made at least partially out of a sufficiently strong and durable material. Good results are achieved in that the sheath is made out of durable stainless steal or another appropriate durable material. Thereby it becomes possible to firmly hold the drilling device during operation although when high forces have to be applied. One advantage consists in that the sheath can be manipulated like a surgeon needle and is thereby fully functional as a driller. Alternatively to the forceps the drilling device can be held and guided by a mechatronic device, such as a robot. Thereby it becomes possible to drive the drilling device through hard material. The mechatronic device can be programmed such that it functions fully autonomous along a circular trajectory in three dimensional space, or alternatively or in addition semi-active, activated by the surgeons hand, but restricted to a pre-defined circular trajectory. The mechatronic device in general comprises or is interconnected to a CPU (Central Processing Unit) which is suitable to operate the mechatronic device in a predetermined manner based on a computer program held in a memory. The mecha- tronic device further comprises a holding means, e.g. in form of an automatically activated forceps, to hold and guide the drilling device.

If appropriate it is possible to co-registering the object to be drilled and the sheath with one or more registered images of the object (e.g. 2D: X-ray, Fluoroscopy, Endoscopy; Ultrasound, etc. and 3D: CT, MRI, PET, SECT, etc.) al- lows image guided preparation of the drill canal. Co-registration means that appropriate coordinate systems are defined on members to be co-registered and that the transformations between these coordinate systems of both members are known for arbitrary motions of these members in space at any time. These real-time transformations could be provided by tracking systems or mechatronic devices, such as robots as e.g. known in image guided surgery. Circular trajectories can be predefined in registered images. Image guided realization of these trajectories can then be realized by using object co-registration as previously described e.g. in combination with a tracking system and/or a mechatronic device. In an embodiment the sheath and the drive shaft are demountable from each other although the sheath is still in a drilled canal. Therefore the drive shaft is designed at least at one end such that it can be easily removed from the sheath and reinserted if necessary. When the sheath temporarily remains in the canal it may act a as a guiding means to guide the passage there through of a sufficiently stiff twine or wire. The drive shaft may further be equipped with a fastening means to which the twine or wire may temporarily be attached such that it can be pulled through the sheath by the drive shaft.

Due to the rigid sheath it is always assured the drilling canal exactly corre- sponds in its size and form to the diameter of the drilling bit and the radius of the sheath. Depending on the field of application the sheath has a curvature with a constant radius or is straight (infinite radius). The radius is normally in the range of 5mm to 60mm. In general the diameter of the drilling bit is bigger than the diameter of the sheath such that an annular canal results between the in- side wall of the drilled canal and the outside wall of the sheath. This annular canal is necessary for the backward evacuation of the drilled material. In general the annular canal has a width which corresponds approximately to 5% to 20% of the diameter of the drilling bit. Depending on the field of application the sheath may be used to guide cooling and/or flushing fluid to the drilling bit. Along the sheath and/or between the drilling bit and the sheath exit opening may be foreseen to guide the fluid into the annular canal.

In an embodiment the sheath is designed without any protrusion protruding above the drilling bit, i.e. the outer diameter of the sheath does nowhere extend above the outer diameter of the drilling bit. Thereby it becomes possible to re- move a sheath arranged in a drilling canal forward or backward from the drilling canal with the choice given to the operator.

An embodiment of the drilling device comprises a cutting bit and a flexible drive shaft interconnected to the cutting bit. The drilling device further comprises a sheath which at least partially surrounds and laterally supports the flexible shaft. The sheath has a maximal outer diameter which is less then or equal to the diameter of the cutting bit such that the sheath can be removed forward and backward from a drilling canal. The sheath in general has a constant radius R. Normally the drive shaft is significantly longer then the sheath such that a rela- tive movement is possible. E.g. the drive shaft is 1.5-times longer then the sheath. Depending on the field of application the sheath may comprise a rigid front part and a flexible rear part acting as a housing for the drive shaft. The drive shaft may further comprise at its rear end a connector which acts as a standardized connecting means. A kit for assembly of a drilling device accord- ing to the invention in general comprises at least one drilling bit, at least one drive shaft and at least one sheath. If appropriate the kit also comprises a forceps to securely hold the drilling device during operation.

The diameter of the drilling bit is normally in the range of 1 mm to 6mm and the radius of the sheath is in the range of 5mm to 200mm.

Depending on the field of application when the making of a curved hole is not the primary target, the rigid sheath can be designed with a discontinuous radius or a sharp bend, e.g. hockey stick like with two in general straight sections interconnected by a sharp bend. These embodiments may be applicable in surgi- cal applications such as osteotomy or to remove tumors, e.g. through an opening of the cranium (e.g. nose).

An embodiment of the invention is directed to a drilling device which comprises a cutting bit and a flexible drive shaft which is interconnected to the cutting bit. The drilling device further comprises a rigid sheath which is at least partially surrounding and laterally supporting the flexible shaft whereby the sheath has a maximal outer diameter which is less then or equal to the diameter of the cutting bit. Thereby it becomes possible to remove the sheath forward and backward from a drilling canal. The sheath preferably has a constant radius. In general the drive shaft is substantially longer then the rigid sheath, e.g. at least 1.5-times longer then the length of the sheath. If appropriate the sheath comprises a rigid front part and a flexible rear part. The drilling device may comprise at its rear end a connector which acts as a standardized connecting means. To operate the drilling device, the drilling device is designed such that it can be clamped by a forceps. Depending on the field of application, the forceps may be part of a mechatronic device, such as a robot.

A kit for assembly of a drilling device according to the present invention in general comprises at least one drilling bit, at least one drive shaft and at least one sheath. The kit may comprise a forceps to clamp the sheath.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the detailed description given herein below and the accompanying drawings which should not be considered limiting to the invention described in the appended claims.

Fig.1 shows a side view of a drilling device;

Hg. 2 shows a front view of the drilling device according to Fig. 1 ;

Fig. 3 shows a drilling device held by a forceps;

Fig. 4 shows a kit for assembly and handling of a drilling device.

DESCRIPTION OF THE EMBODIMENTS Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.

Figure 1 illustrates a side view and Figure 2 a front view of a drilling device 1 according to the present invention. The drilling device 1 comprises a drilling bit 2 which is mechanically interconnected via a flexible drive shaft 3 to a connector 4 by which it can be interconnected directly or indirectly to a drive unit (not shown in detail), e.g. an electric, pneumatic or hydraulic motor. Thereby it be- comes possible to spin the drilling bit 2 by the drive unit via the drive shaft 3 at an appropriate speed such that a canal 10 can be drilled in a bone 11 (sche- matically illustrated in Figure 1). If appropriate the drive shaft 3 can be extended in its length by an elongator (not shown in detail). In normal operation mode, the drive shaft 3 adjacent to the drilling bit 2 of the shown embodiment is laterally and in axial direction guided in a rigid, non-bendable tubular sheath 5 having a certain constant radius R and which acts as a housing for the drive shaft 3. In Figure 1 the drilling device 1 is shown in working position with the drilling bit 2 in contact with a front end of the sheath 5. The sheath 5 acts at its front end as a rotation-free bearing for the drilling bit 2 in lateral (x, y) and longitudinal direction (z). If appropriate the sheath 4 may comprise a bushing, e.g. made out of ceramic or another suitable material. The maximal outer diameter D2 of the sheath 5 does not protrude above the maximal outer diameter D1 of the drilling bit 2. Thereby the sheath can be manipulated similar to a surgeon needle still remaining fully functional as a driller. In general the outer diameter D1 of the drilling bit 2 is about 5 to 20% bigger then the outer diameter D2 of the sheath 5, such that an annular canal 13 results between the inner side wall of the drilled canal 10 and the outer side wall of the sheath 5. This annular canal can be used to evacuate drilled material. A further advantage results in that the sheath can be removed from the canal without efforts.

A further advantage consist in that becomes possible to remove the sheath 5 forward or backward from the canal 10 (see Figure 1). The flexible drive shaft 3 is in general made out of a sufficiently torsion proof piano wire. The connector 4 can be completely integrated in the distal end of the drive shaft 4 or be made as a standardized connecting means, e.g., as herein shown, as a four cornered shaft by which the drilling device can be interconnected to a thereto compatible coupling device of a drive unit (both not shown in detail). However, when the drive shaft must be removed from the sheath 5 it is important that the connector 4 is designed such that it can be passed through the sheath 3 or temporarily be removed from the drive shaft 3. The drive shaft of the shown embodiment is freely displaceable with respect to the sheath 5 in at least one direction. However, the drilling bit 2 avoids that the drive shaft 3 can be pulled backwards into the sheath 5 in an unwanted manner.

Figure 3 shows how the sheath 5 of the drilling device 1 is held at its distal end by a forceps 6. Due to the specific design and shape it becomes possible to handle the drilling device 2 like a surgical needle. The herein shown drive shaft 3 is shown in an intermediate, non-drilling position partially remove from the sheath 5. In that the drilling bit 2 and the driving shaft 3 can be freely removed (without further manipulation) from the sheath 5 it becomes possible to operate the drilling device 1 in areas with only very limited space available. If additional disassembly operations would be necessary the efficiency of the device would suffer.

Figure 4 shows in a perspective manner a kit 12 by which a drilling device 1 (see Figure 1 to 3) according to the present invention can be assembled. The kit 12 in general comprises at least one drilling bit 2, at least one drive shaft 3 and at least one tubular sheath 5.1 , 5.2, 5.3. As it can be seen the connector 4 of the shown embodiment of the drive shaft 3 is fully integrated in the rear end of the drive shaft 3. If appropriate, the kit 12 further comprises a forceps 6 designed to securely hold the drilling device 1 during operation. The kit 12 may comprise sheath 5.1 , 5.2, 5.3 of different size (radius, length, diameter) or design. If appropriate the sheath 5.3 may comprise adjacent to the rigid front part 5.4 a flexible, bendable rear part 5.5 which houses during operation a rotating drive shaft on its inside. The bendable rear part 5.5 is e.g. made out of a metal coil or a plastic tube. Good results are achieved in that the bendable part is made out of a flexible silicon tube. The bendable rear part 5.5 may be designed detachable from the rigid front part 5.4. If appropriate the sheath may act as a canal for cooling fluid to cool the drilling area or as a suction tube to extract Hq- uids and material during operation by suction.

Claims

PATENT CLAIMS

1 Drilling device (1) with a cutting bit (2) and a flexible drive shaft (3) interconnected to the cutting bit (2) and a sheath (5) at least partially surround- ing and laterally supporting the flexible shaft (3) whereby the sheath (5) has a maximal outer diameter (D2) which is less then or equal to the diameter (D1) of the cutting bit (2) such that the sheath (5) can be removed forward and backward from a drilling canal (10).

2 The drilling device (1) according to claim 1 , characterized in that the sheath (5) has a constant radius R.

3 The drilling device (1) according to one of the previous claims, characterized in that the drive shaft (3) is longer then the sheath (5).

The drilling device (1) according to claim 2, characterized in that the length of the drive shaft (3) is at least 1.5-times longer then the length of the sheath (5).

The drilling device (1) according to one of the previous claims, characterized in that the sheath (5.3) comprises a rigid front part (5.4) and a flexible rear part (5.5).

6 The drilling device (1) according to one of the previous claims, character- ized in that the drive shaft (3) comprises at its rear end a connector (4) which acts as a standardized connecting means. The drilling device (1) according to one of the previous claims, characterized in that the drilling device (1) is designed such that it can be clamped by a forceps (6).

The drilling device (1) according to claim 7, characterized in that the for- ceps (6) is part of a mechatronic device.

Kit for assembly of a drilling device (1) according to one of the previous claims, comprising at least one drilling bit (2), at least one drive shaft (3) and at least one sheath (5).

The kit according to claim 9, characterized in that the kit comprises a forceps (6) to clamp the sheath (5).