AU2089600A

AU2089600A - Device with a flexible shaft for removing bone grafts

Info

Publication number: AU2089600A
Application number: AU20896/00A
Authority: AU
Inventors: Max Aebi; Markus Hehli; Thomas Steffen; Beatrice Steiner
Original assignee: Synthes AG Chur
Current assignee: Synthes GmbH
Priority date: 1999-02-02
Filing date: 2000-01-31
Publication date: 2000-08-25
Anticipated expiration: 2020-01-31
Also published as: CN1338911A; NZ513134A; CN101836876B; EP1148824B1; EP1148824A1; ES2290009T3; DE29901724U1; JP4156806B2; CA2371761A1; DE50014543D1; AU758769B2; ATE369076T1; JP2002537007A; CN101836876A; ZA200105287B; CA2371761C; WO2000045713A1

Abstract

The invention relates to a device for removing bone grafts, comprising a cutting tool (16) with a cutting head (1), a longitudinal shaft (8) attached to the cutting head (1) and driving means (14) for the rotational movement of the cutting tool (16), wherein the bone grafts that have been cut by the cutting head (1) can be conveyed through a continuos bore (10) in the cutting tool (16), the shaft (8) is elastically mounted on a part (22) attached to the cutting head (1) enabling torsion and/or bending around the longitudinal axis, the device can additionally comprise a vacuum container (17) and the shaft (8) can also be attached to the container (17) during cutting and removal of bone grafts by the end (21) which is distant from the cutting head (1).

Description

1725/PCT 28.1.2000 English translation of the International Patent Application 5 No. PCT/CHOO/00047 in the name of Synthes AG Chur Apparatus with a flexible shaft for harvesting bone fragments 10 The invention relates to an apparatus for harvesting bone fragments as claimed in the precharacterising part of claim 1. The implantation of endogenous bone material remains the 15 most efficient procedure for treating non united fractures, pseudo-arthrosis, and for optimising the chances of success in cases of arthrodesis. The utilisation of endogenous bone material is safer and more efficient than the utilisation of man-made hydroxyapatite materials or exogenous bone 20 fragments but, on the other hand, necessitates an additional surgical intervention in the patient's body. The scope of this intervention can be minimised by a limited penetration and by the use of a cylindrical needle of the type used for the removal of bone material for diagnostic 25 purposes. However, this technique is complicated and implies a number of risks, as no precise control is possible. For this reason the spongiosa is usually chiselled out from the iliac crest through a large opening, requiring a major skin incision. Special bone chip 30 collecting instruments make it possible to harvest endogenous bone chips safely and rapidly, necessitating only a small skin incision, so that the patient's strain and injury can be minimised. These apparatuses safely 2 remove bone material and may be used with a drilling machine, thus allowing to harvest greater quantities with better control and minimising the risk of an inadvertent penetration of the cortical bone. This safe and efficient 5 technique makes it possible to harvest endogenous bone chips for such purposes as fusions, pseudo-arthrosis and fractures while injuring the donor as little as possible. The removal of bone chips from the patient's body will usually occur in the area of the pelvic bone. Other regions 10 for removing usable bone material are the proximal part of the ulna or the distal part of the radius. An apparatus of this type for harvesting bone material is known, for example, from WO 97/39685 YUAN. This known 15 apparatus comprises a rigid, transparent shaft in the form of a hollow cylinder wherein the bone chips are collected, the quantity of collected chips being easily visible due to the transparent shaft, a cutting head arranged on the one end portion and means for receiving a turning moment 20 arranged on the other end portion of the shaft. The apparatus is simply screwed into the bone, the cutting head having the function of cutting and removing chips of bone. The bone chips are received and collected in the cavity of the shaft. The collected bone fragments are then, as 25 needed, removed from the shaft by means of a piston which is inserted into the cavity of the shaft from the side opposite the cutting head. As to the source of rotational drive power, the apparatus may be driven by hand or by motor. 30 Another apparatus of this type for harvesting bone material is known from US 5,556,399 HUEBNER. This known apparatus equally comprises a drilling head with an adjoining, rigid 3 shaft in the form of a hollow cylinder where the bone chips are collected and from where they are subsequently removed by means of a manually actuated piston which is to be introduced into the cavity from the side of the drilling 5 head. A method and an apparatus for harvesting tissue is known from US 5,403,317 BONUTTI. This known invention comprises an apparatus for percutaneous tissue removal and includes a 10 drill shaft flexibly deformable with respect to bending, as well as means for transmitting motion to the shaft. On the front portion of the shaft, a cutting tip is mounted for cutting tissue fragments from the tissue. During the cutting process, the tissue fragments are removed along the 15 shaft by suction to a location outside the body. All these known apparatuses suffer from the disadvantage that due to the torsional rigidity of the shaft there is a risk of cutting or penetrating the harder cortical bone 20 during the process of reaming the spongiosa lying between said cortical portion of the bone. The invention is intended to provide a remedy for this. It is accordingly an object of the invention to develop an 25 apparatus permitting to ream the spongiosa between the cortical bone in a simple manner without cutting or penetrating the harder cortical portion of the bone. According to the invention, this object is achieved by 30 means of an apparatus for harvesting bone chips which shows the features of claim 1.

4 Further advantageous embodiments of the invention will be characterised in the dependent claims. The advantages achieved by the present invention consist 5 basically in the fact that the resilient deformability of the shaft combined with a not too sharp-edged cutting head make it possible to ream the spongiosa lying between the cortical bone without running the risk, in doing so, of cutting, or penetrating, the harder cortical portion of the 10 bone. The apparatus according to the invention comprises a hollow, cylindrical cutting tool including a hollow, cylindrical cutting head which may have cutting bits and 15 cutting edges of various different shapes, a hollow, cylindrical shaft with means for mounting said shaft on a drive unit, and a drive unit which may consist, for example, of a universal drilling machine. The configuration of the cutting head and the shaft in the form of hollow 20 cylinders permits the bone chips removed from the spongiosa by the cutting head to be received in the bore arranged within said hollow cylinders. Adjoining the cutting head, the shaft is resiliently deformable with respect to twisting and/or bending. 25 This deformability may be achieved by a design of the shaft in the form of a spirally wound sheet metal strip, of a wire-reinforced plastic or rubber hose, or of a metal tube with a bellows-type side wall. 30 The bit of the cutting head is preferably shaped in the form of a calotte sector provided with a cutting edge. The advantages of this configuration of the cutting head reside 5 in the fact that using a not too sharp-edged cutting head or a cutting head provided with rounded edges makes it possible to ream the spongiosa lying between the cortical bone without running the risk, in doing so, of cutting or 5 penetrating the harder cortical portion of the bone. According to a special embodiment of the cutting head, the tip of the cutting head is shaped in the form of a calotte including at least two through holes extending coaxially 10 and radially to the longitudinal axis into the cavity, the edges of the through holes being equipped with cutting edges for removing bone chips, and the removed bone chips being conveyable to the cavity of the cutting head by means of said through holes. 15 In other embodiments, the cutting tips may be shaped in the form of cone sectors with cutting edges or in the form of hollow, cylindrical milling cutters with front teeth. 20 The connection between cutting head and shaft may be conceived as a detachable or a fixed connection, a detachable connection permitting to have a smaller tool set. Detachable connections may be realised in the form of screw joints, radial tap bolts or radial pin connections. 25 In another embodiment of the apparatus according to the invention a vacuum chamber is fixed to the driving element in such a way that the hollow, cylindrical cutting tool with its end portion situated opposite to the cutting head 30 leads to said chamber, the vacuum permitting the bone chips to be conveyed in a simple way through the hollow, cylindrical cutting tool into said chamber and to be collected in said chamber. The chamber is provided with a 6 connection piece for connecting a suction hose permitting to aspirate the bone chips. By means of the vacuum thus created, the bone chips are aspirated through one or several through holes arranged in the cutting head and 5 transported by suction into the bore arranged in the shaft, from where they are conveyed through the entire length of the cutting tool into the chamber. In order to prevent the bone chips from passing into the suction hose, a separator is arranged in the chamber for separating the bone chips 10 from the air flow. This separator may be realised in the form of a filter, a sieve, a deflector or a cyclone. This configuration of the apparatus according to the invention makes it possible, without removing the cutting 15 tool, to convey the bone chips from the cutting tip through the shaft away from the drilled hole and to harvest them in a chamber located immediately adjacent to the cutting tool. The chamber may be detached from the apparatus and the bone chips are easily removable from said chamber, in accordance 20 with the surgeon's needs. The vacuum applied to the chamber comprises a negative pressure ranging between 0 bar and 1 bar, preferably however between 0.2 bar and 0.8 bar. 25 In order to seal the bore extending through the shaft of the cutting tool, said bore is preferably lined with a rubber or plastic hose. 30 In the following, the invention and further developments of the invention will be illustrated in greater detail with reference to the partially diagrammatic representations of several embodiments.

7 In the drawings: Fig. 1 is a view of the cutting tool with a flexible shaft 5 in accordance with one embodiment of the apparatus according to the invention; Fig. 2 is a perspective view of the cutting head with a flexible shaft in accordance with one embodiment of the 10 apparatus according to the invention; Fig. 3 is a diagrammatic representation of one embodiment of the apparatus according to the invention; and 15 Fig. 4 is a diagrammatic representation of another embodiment of the apparatus according to the invention. Fig. 1 represents the cutting tool 16 including a cutting head 1 and a shaft 8. The shaft 8 comprises a portion 22 20 resiliently deformable with respect to twisting and/or bending, and a portion 11 distant from the cutting head 1 and provided with means 13 for receiving a turning moment. The means 13 consist of a hexagonal segment 25 and an adjoining, cylindrical segment 27 provided with a groove 25 26. The two segments 25 and 27 may be mounted in a corresponding chuck 15 (Fig. 3) of a drive means 14 (Fig. 3), the shaft 8 being releasably lockable within the chuck 15 (Fig. 3) with respect to axial displacement by means of the groove 26 and with respect to rotational displacement 30 by means of the hexagonal segment. The bore 10 arranged in the hollow, cylindrical shaft 8 penetrates said shaft 8 in the direction of the longitudinal axis 2 beginning at the cutting head 1 and extending right through to the end 8 portion 21 located opposite to the cutting head 1, so that the bone chips removed by the cutting head 1 may be conveyed along the longitudinal axis 2 through the inside of the cutting tool 16. The fixation of the cutting head 1 5 on the shaft 8 may be realised by means of set screws or, for example, by means of spring bolts arranged between the shaft 8 and the cutting head 1. The resiliently deformable portion 22 of the shaft 8 is made of a spirally wound sheet metal strip, the bore 10 being lined with a rubber or 10 plastic hose 36 (Fig. 4), said hose 36 ensuring a tight sealing of the bore with respect to the ambient air. Fig. 2 shows one embodiment of the cutting head 1. The cutting head 1, realised in the form of a hollow cylinder 15 including a longitudinal axis 2 and a cutting tip 20, comprises a front segment 4 adjoining the cutting tip 20 and a rear segment 5 distant from the cutting tip 20. The front segment 4 consists of a hollow cylinder including a cutting tip 20 shaped in the form of a calotte sector, the 20 side wall of the front segment 4 as seen in a cross sectional view at a right angle with the longitudinal axis 2 forming only a sector of an annulus, so that a through hole 7 is formed which extends radially to the hollow, cylindrical portion and axially to the cutting tip 20. The 25 side wall of the front segment 4 extending from the cutting tip 20 to the rear segment 5 is realised in the form of a cutting edge 3 leading to the through hole 7. As the rotating cutting head 1 is drilled into the bone, bone chips are removed by the cutting edges 3 and pass through 30 the through hole 7 into the cavity 9 of the cutting head 1 from where they are conveyed through the bore 10 arranged in the shaft 8.

9 Fig. 3 shows a preferred embodiment of the apparatus according to the invention. The cutting tool 16, which serves for harvesting bone chips, consists of a cutting head 1 with a hollow, cylindrical shaft 8 extending along 5 the longitudinal axis 2. This shaft 8 is locked with respect to axial and rotational displacement in the chuck 15 of a universal drilling machine 30 serving as drive means 14. The drive means 14 confer to the shaft 8 equipped with the cutting head 1 a rotatory movement about the 10 longitudinal axis 2, causing the cutting head 1 to drill itself into the bone and to remove the bone chips to be harvested. The shaft 8, from the cutting head 1 to the end portion 21 located opposite to the cutting head 1, is shaped in a hollow, cylindrical form, so that the bone 15 chips may be conveyed along the entire length of the cutting tool 16. In addition, a recipient for receiving the bone chips, referred to as chamber 17, is fixed to the drive means 14. Extending coaxially to the longitudinal axis 2, the chamber 17 with its front end portion 24 is 20 releasably connected to the drive means 14 in such a way that the end portion 21 of the cutting tool 16 located opposite to the cutting head 1 leads to the chamber 17, the point of contact between the two being realised in such a way as to ensure a tight sealing with respect to the 25 ambient air. On its end portion 23, situated opposite to the shaft 8, the chamber 17 is provided with a connection piece 18 to which a suction hose (not shown) may be connected. Due to the vacuum existing in the suction hose the chamber 17 is equally evacuated, thus creating a 30 negative pressure inside the hollow, cylindrical cutting tool 16 whereby the bone chips removed by the cutting head 1 are transported by suction through the interior of the shaft 8 and into the chamber 17 where they may be 10 subsequently collected. In order to prevent the bone chips from being carried along by the vacuum into the suction hose, a separator 19, which in the preferred embodiment is realised in the form of a filter, is arranged in the 5 chamber 17 in such a way that the bone chips are kept from passing through the connection piece 18. Fig. 4 shows another preferred embodiment of the apparatus according to the invention. The embodiment of the apparatus 10 according to the invention shown here differs from the embodiment shown in Fig. 3 only in so far as the cutting tool 16 extends through the chamber 17 arranged coaxially to the longitudinal axis 2 and that the means 13 for receiving a turning moment imparted by the universal 15 drilling machine 30 are releasably connected with said universal drilling machine 30 in the area of the chamber bottom 33 located opposite to the cutting head 1. The chamber 17 is releasably connected with the universal drilling machine 30 by means of the chamber bottom 33. 20 Instead of a cover, the chamber 17 is provided with a bearing housing 34 wherein the cutting tool 16 with respect to its rotatory movement about the longitudinal axis 2 is mounted for example by means of roller bearings 35, the chamber 17 being sealed with respect to the ambient air by 25 means of an annular sealing 37. In addition, the connection piece 18 for connecting a suction hose is arranged on the side wall of the chamber 17. The sealing of the flexible shaft 8 is realised by means of a rubber or plastic hose 36 lining the bore 10 of said shaft along the longitudinal 30 axis 2.

Claims

1. An apparatus for harvesting bone chips comprising A) a rotatable cutting tool (16) with a longitudinal axis 5 (2), a cutting head (1), and a longitudinal shaft (8) adjoining the cutting head (1) and extending concentrically to the longitudinal axis (2); and B) drive means (14) which confer to the cutting tool (16) equipped with the cutting head (1) a rotatory movement 10 about the longitudinal axis (2); with C) the cutting tool (16) having a bore (10) penetrating it in the direction of the longitudinal axis (2), and the cutting head (1) being provided with at least one through hole (7) so that the bone chips removed by the cutting 15 action of the cutting head (1) may be conveyed through the bore (10), characterized in that D) the shaft (8) is resilient at least on part of its length with respect to twisting and/or bending. 20

2. An apparatus as claimed in claim 1, characterised in that the shaft (8) is made of a spirally wound metal strip.

3. An apparatus as claimed in claim 1 or 2, characterised 25 in that the bore (10) of the cutting tool (16) is additionally lined with a plastic or rubber hose extending along the longitudinal axis (2).

4. An apparatus as claimed in claim 1 or 3, characterised 30 in that the shaft (8) is made of a metal tube with a bellows-type side wall. 12

5. An apparatus as claimed in any of the claims 1 to 4, characterised in that the cutting head (1) is realised in the form of a hollow cylinder and comprises a cavity (9) extending along the longitudinal axis, a front segment (4) 5 provided with a cutting tip (20) and with at least one cutting edge (3), a hollow, cylindrical rear segment (5), and at least one through hole (7) radially penetrating the outside wall (29) of the cutting head (1) in the front segment (4) and serving for conveying the bone chips 10 removed by the at least one cutting edge (3) to the cavity (9) of the cutting head (1).

6. An apparatus as claimed in claim 5, characterised in that the cutting tip (20) of the cutting head (1) is 15 realised in the form of a calotte sector.

7. An apparatus as claimed in claim 5, characterised in that the cutting tip (20) of the cutting head (1) is realised in the form of a calotte having at least two 20 through holes (7) extending coaxially and radially to the longitudinal axis (2) into the cavity (9), the edges of the through holes (7) being provided with cutting edges (3) for removing bone chips and the removed bone chips being conveyable through the through holes (7) to the cavity (9) 25 of the cutting head (1).

8. A device as claimed in any of the claims 1 to 7, characterised in that the drive means (14) consist of a universal drilling machine (30). 30

9. An apparatus as claimed in any of the claims 1 to 8, characterised in that the cutting tool (16) is realised, over its entire length, in the form of a hollow cylinder, 13 that it comprises means (13) for receiving a turning moment which causes a rotation of the shaft (8) about the longitudinal axis (2), and that with its end portion (12) connectable to the cutting head (1) it may be connected to 5 the rear segment (5) in such a way that the bore (10) of the hollow, cylindrical shaft (8) may be aligned flush with the cavity (9) and that the turning moment may be transmitted from the shaft (8) to the cutting head (1).

10 10. An apparatus as claimed in claim 9, characterised in that the drive means (14) comprise chucks (15) for locking the means (13) provided on the cutting tool (16) against rotative and axial displacement. 15

11. An apparatus as claimed in any of the claims 1 to 10, characterised in that the apparatus comprises a chamber (17) in which a vacuum is created and that the cutting tool (16) on its end portion (21) located opposite to the cutting head (1) is connectable to said chamber (17) even 20 while the cutting and harvesting of bone chips is in progress.

12. An apparatus as claimed in claim 11, characterised in that the chamber (17) in alignment with the longitudinal 25 axis (2) is releasably connected to the drive means (14), the chamber (17) being immobile with respect to the longitudinal axis (2) and the end portion (21) of the rotating, hollow, cylindrical cutting tool (16) located opposite to the cutting head (1) leading to said chamber 30 (17), the point of connection between the two being sealed by an annular sealing so that the transition point between the cutting tool (16) and the chamber (17) is tightly sealed against the ambient air. 14

13. An apparatus as claimed in claim 11 or 12, characterised in that the chamber (17) is provided with a connection piece (18) for connecting a suction hose. 5

14. An apparatus as claimed in any of the claims 11 to 13, characterised in that the chamber (17) comprises a separator (19) for separating the bone chips from the air flow. 10

15. An apparatus as claimed in claim 14, characterised in that the separator (19) consists of a filter.