AU758769B2

AU758769B2 - Device with a flexible shaft for removing bone grafts

Info

Publication number: AU758769B2
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: 2003-03-27
Anticipated expiration: 2020-01-31
Also published as: DE50014543D1; WO2000045713A1; ZA200105287B; EP1148824A1; CN101836876B; CN1338911A; JP4156806B2; ATE369076T1; CA2371761C; EP1148824B1; DE29901724U1; CA2371761A1; NZ513134A; ES2290009T3; CN101836876A; JP2002537007A; AU2089600A

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

Apparatus with a flexible shaft for harvesting bone fragments The invention relates to an apparatus for harvesting bone fragments.

The implantation of endogenous bone material remains the 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 S implies a number of risks, as no precise control is 0S 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 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 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 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, 00..

oo: the quantity of collected chips being easily visible due to tooe.

0. the transparent shaft, a cutting head arranged on the one end portion and means for receiving a turning moment .000o: 20 arranged on the other end portion of the shaft. The oo.. apparatus is simply screwed into the bone, the cutting head having the function of cutting and removing chips of bone.

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The bone chips are received and collected in the cavity of the shaft. The collected bone fragments are then, as o• 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.

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 Rshaft in the form of a hollow cylinder where the bone chips are collected and from where they are subsequently removed r V:\VioetWodeIeteO896-OO.doc 3 by means of a manually actuated piston which is to be introduced into the cavity from the side of the drilling 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 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 shaft by suction to a location outside the body.

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15 Another device for harvesting bone material is known from US 4,646,738 TROTT. This known device comprises an exterior tube-like part and interior tube-like part, whereby at one end of the interior tube-like part a cutting tool is attached. The interior tube-like part is rotatably 20 arranged within the exterior tube-like part, while the exterior tube-like part is manufactured of a deformable eroe material and is selectively bendable.

*S oo S.Yet, another device for harvesting bone material is known from WO 96/39956 AUST. This known device comprises a thinwalled hollow cylindrical shank which is externally enclosed through a spiral spring.

The above discussion of background art is included to explain the context of the invention. It is not to be taken as an admission or suggestion that any of the documents or other material referred to was published, known or part of the common general knowledge in Australia at the priority date of any one of the claims of this AI specification.

W:\%Vlet\~odee0-OO .do c All the apparatuses described above 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 during the process of reaming the spongiosa lying between said cortical portion of the bone.

The present invention aims to provide a remedy for this.

Accordingly, it would be desirable to develop an 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.

Broadly, the present invention provides an apparatus for 15 harvesting bone chips including: a rotatable cutting tool with a longitudinal axis, a 9o cutting head, and a longitudinal shaft adjoining the cutting head and extending concentrically to the longitudinal axis; and S 20 drive means which confer to the cutting tool equipped *9*9 with the cutting head a rotational movement about the S:.longitudinal axis; 9999 the cutting tool having a bore penetrating it in the 99 9o direction of the longitudinal axis, and the cutting head S 25 being provided with at least one through hole so that the bone chips removed by the cutting action of the cutting head may be conveyed through the bore, wherein the shaft is resilient at least on part of its length with respect to twisting and bending; and wherein the bore of the cutting tool is additionally lined with a plastic or rubber hose extending along the longitudinal axis.

3 RMAThe advantages achievable with the present invention relate 3 to the fact that the resilient deformability of the shaft

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WAVoIetNde~te2089 6 OO.dOC 4a 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 bone.

In at least one embodiment, therefore, the apparatus according to the invention comprises a hollow, cylindrical cutting tool including a hollow, cylindrical cutting head which may have cutting bits and 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 cylinders permits the bone 15 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.

20 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.

S 25 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 WN, \wmt oele 0898-O0 d= 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 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 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.

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.

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.

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 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 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 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 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 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 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.

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.

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.

In the drawings: Fig. 1 is a view of the cutting tool with a flexible shaft 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 apparatus according to the invention; Fig. 3 is a diagrammatic representation of one embodiment of the apparatus according to the invention; and 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 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 26. The two segments 25 and 27 may be mounted in a corresponding chuck 15 (Fig. 3) of a drive means 14 (Fig.

the shaft 8 being releasably lockable within the chuck (Fig. 3) with respect to axial displacement by means of the groove 26 and with respect to rotational displacement 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 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 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 plastic hose 36 (Fig. 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 including a longitudinal axis 2 and a cutting tip comprises a front segment 4 adjoining the cutting tip 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 side wall of the front segment 4 as seen in a crosssectional 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 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 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.

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 the longitudinal axis 2. This shaft 8 is locked with respect to axial and rotational displacement in the chuck 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 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 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 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 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 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 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 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 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 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.

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 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 axis 2.

Claims

1. An apparatus for harvesting bone chips including: a rotatable cutting tool with a longitudinal axis, a cutting head, and a longitudinal shaft adjoining the cutting head and extending concentrically to the longitudinal axis; and drive means which confer to the cutting tool equipped with the cutting head a rotational movement about the longitudinal axis; the cutting tool having a bore penetrating it in the direction of the longitudinal axis, and the cutting head being provided with at least one'through hole so that the bone chips removed by the cutting action of the cutting 15 head may be conveyed through the bore, wherein the shaft is resilient at least on part of its length with respect to twisting and bending; and wherein o the bore of the cutting tool is additionally lined with a plastic or rubber hose extending along the longitudinal 20 axis. o o

2. An apparatus as claimed in claim 1, wherein the shaft is made of a spirally wound metal strip. 25

3. An apparatus as claimed in claim i, wherein the shaft 0o is made of a metal tube with a bellows-type side wall.

4. An apparatus as claimed in any one of claims 1 to 3, wherein the cutting head is realised in the form of a hollow cylinder and includes a cavity extending along the longitudinal axis, a front segment provided with a cutting tip and with at least one cutting edge, a hollow, cylindrical rear segment, and at least one through hole radially penetrating the outside wall of the cutting head in the front segment and serving for conveying the bone W: otlNodelete2O896-OO.doC 12 chips removed by the at least one cutting edge to the cavity of the cutting head.

An apparatus as claimed in claim 4, wherein the cutting tip of the cutting head is realised in the form of a calotte sector.

6. An apparatus as claimed in claim 4, wherein the cutting tip of the cutting head is realised in the form of a calotte having at least two through holes extending coaxially and radially to the longitudinal axis into the cavity, the edges of the through holes being provided with cutting edges for removing bone chips and the removed bone chips being conveyable through the through holes to the cavity of the cutting head.

7. A device as claimed in any one of claims 1 to 6, Se wherein the drive means comprises a universal drilling :machine.

8. An apparatus as claimed in any one of claims 1 to 7, wherein the cutting tool is realised, over its entire length, in the form of a hollow cylinder, wherein it includes means for receiving a turning moment which causes 25 a rotation of the shaft about the longitudinal axis, and '-"-wherein with its end portion connectable to the cutting :head it may be connected to the rear segment in such a way that the bore of the hollow, cylindrical shaft may be aligned flush with the cavity and that the turning moment may be transmitted from the shaft to the cutting head.

9. An apparatus as claimed in claim 8, wherein the drive means include chucks for locking the means provided on the cutting tool against rotative and axial displacement.

An apparatus as claimed in any one of claims 1 to 9, 4wherein the apparatus includes a chamber in which a vacuum W:\VIoeIet~lNodelete\2O896-OO.doc 13 is created and wherein the cutting tool on its end portion located opposite to the cutting head is connectable to said chamber even while the cutting and harvesting of bone chips is in progress.

11. An apparatus as claimed in claim 10, wherein the chamber in alignment with the longitudinal axis is releasably connected to the drive means, the chamber being immobile with respect to the longitudinal axis and the end portion of the rotating, hollow, cylindrical cutting tool located opposite to the cutting head leading to said chamber, the point of connection between the two being sealed by an annular sealing so that the transition point :.:.:between the cutting tool and the chamber is tightly sealed 15 against the ambient air. S.. o

12. An apparatus as claimed in claim 10 or claim 11, e wherein the chamber is provided with a connection piece for connecting a suction hose. o o

13. An apparatus as claimed in any one of claims 10 to 12, :wherein the chamber includes a separator for separating the 9. bone chips from the air flow. 9. 9 25

14. An apparatus as claimed in claim 13, wherein the separator consists of a filter. An apparatus for harvesting bone chips substantially as herein described with reference to the accompanying drawings. DATED: 22 August 2001 PHILLIPS ORMONDE FITZPATRICK Attorneys for: SSYNTHES AG CHUR