A SURGICAL DEVICE FOR INTERNAL PROCESSING OF A HOLE

Abstract: The present invention relates to a surgical instrument (1) for internal working of holes (31) in bone tissue (30), said instrument (1) having a longitudinal direction (A) which is axial and a transverse direction (B) which is radial, and said instrument (1) comprising a first upper end (2), a first lower end (3) and an instrument shaft (4), said instrument shaft (4) having a second upper end (5), a second lower end (6), a first cross-sectional surface (C) and a first external diameter (D), with means (7; 47) which are arranged at said second upper end (5) and are inteded for cutting work, and, at said first lower end (3), with a construction for axial rotation of said instrument (1), said means (7; 47) for cutting work comprising a cutting surface (8; 48), which cutting surface (8; 48), during the internal cutting work, is partially situated outside said first cross-sectional surface (C) in relation to the transverse direction (B).

Description: A surgical device for internal processing of a hole TECHNICAL FIELD The present invention relates to a surgical instrument for internal working of holes in bone tissue, said instrument having a longitudinal direction which is axial and a transverse direction which is radial, and said instrument comprising a first upper end, a first lower end and an instrument shaft, said instrument shaft having a second upper end, a second lower end, a first cross-sectional surface and a first external diameter, with means which are arranged at said second upper end and are intended for cutting work, and, at said first lower end, with a construction for axial rotation of said instrument. PRIOR ART In surgery there is sometimes a need to form holes in human or animal bone tissue. A special case where it may be necessary to form holes in bone tissue is in the treatment of injuries to the joints and soft tissues, for example when tendons, ligaments or other soft tissue have to be fixed to bone. To fix soft tissue to bone, various types of implants can be used, for example suture anchors, the implant being secured to said bone, for example, by being secured in holes in the bone. The implant has to be stable and has to be firmly anchored in the bone in order to permit satisfactory fixing of the soft tissue. The way in which the hole for securing the implant is made in the bone can have a crucial influence on the secure and stable anchoring of the implant in the bone. Drills, awls and cutting tools are examples of different instruments used for forming holes in bone tissue. For example, US-A-5,785,522 describes a surgical drill used for making holes in bones for implants. Moreover, the instruments are sometimes also used in different ways for working on already existing holes, such as in US-A-4, 341 ,206 which describes a tool for producing holes in bone, the size of said tool varying axially in order to produce holes with a certain diameter toward the inside and a greater diameter toward the outside at the mouth of the hole in the bone. DISCLOSURE OF THE INVENTION We have developed a novel surgical instrument for internal working of holes in bone tissue. By means of this internal working with said instrument, it is possible to create holes in bone tissue, which holes have a diameter which is greater internally than it is at their mouth in the bone tissue. Said instrument comprises an instrument shaft and a cutting surface, and, during the internal cutting work, said cutting surface is partially situated outside a first cross-sectional surface of the instrument shaft in relation to the transverse direction of the instrument. The fact that the cutting surface of said instrument is partially situated outside said first cross-sectional surface in relation to the transverse direction means that a hole which has been created can be widened internally, thus permitting holes which have a greater diameter towards the inside than they do at the mouth of the hole. Holes in bone tissue which have been worked internally with said instrument have many conceivable applications in different areas of use. One example is in the use of devices for fixing an object in a hole in bone tissue, for example the use of a device which we have developed. Said device, which we have developed, has a special design and can be inserted axially, in compressed form, into a hole and then resume its normal shape in the hole if there is space for this when the compression ceases. When the compression ceases and the device recovers its normal shape, the device can be held in engagement in the hole by means of the fact that the external diameter of the device is greater than the diameter of the mouth of the hole. This device is expediently inserted into holes which have been widened internally with a surgical instrument according to the present invention since, with said instrument, it is possible to create holes which have a distinct internal shoulder. For example, said holes can be widened internally in the trabecular bone tissue which is soft and lies to the inside of the harder cortical bone tissue. Said surgical instrument can also be used in dentistry, for example. A small insertion hole minimizes the mechanical damage to the tooth enamel as caries attacks lie principally inside the tooth enamel. Said surgical instrument can also be used for example for treating skeletal injuries or for removing unwanted tissue or foreign material, which tissue and material are mainly situated under the cortical bone tissue. In addition, said instrument should be able to be used for intramedullary administration of medication. Therefore, by virtue of the fact that said cutting surface, during the internal cutting work, is partially situated outside a first cross-sectional surface of the instrument shaft in relation to the transverse direction of the instrument, said surgical instrument can be used in the applications mentioned, although other expedient applications are also included in the scope of application of the instrument. The internally worked holes which can be created with said instrument according to the present invention thus afford possibilities for new and better solutions in surgery. The present invention relates to a surgical instrument for internal working of holes in bone tissue, said instrument having a longitudinal direction which is axial and a transverse direction which is radial, and said instrument comprising a first upper end, a first lower end and an instrument shaft, said instrument shaft having a second upper end, a second lower end, a first cross-sectional surface and a first external diameter, with means which are arranged at said second upper end and are intended for cutting work, and, at said first lower end, with a construction for axial rotation of said instrument, said means for cutting work comprising a cutting surface, which cutting surface, during the internal cutting work, is partially situated outside said first cross-sectional surface in relation to the transverse direction. Said instrument can be made, for example, of stainless steel or of another corrosion-resistant material and is preferably made of a material which has good cutting properties. Said longitudinal direction extends from the first lower end of the instrument to the first upper end of the instrument, and said transverse direction extends across said longitudinal direction. Moreover, said first cross- sectional surface preferably has a substantially circular shape. A further embodiment according to the present invention concerns an instrument in which said cutting surface, during the internal cutting work, has a first extent, which first extent is said part's greatest extent, during the internal cutting work, in said transverse direction outside said first cross- sectional surface. Moreover, there is a first ratio between said first extent and said first diameter, said first ratio being at least 0.15. Further embodiments according to the present invention concern instruments in which said first ratio is at least 0.20, 0.25, 0.30, 0.35, 0.40, 0.45 or 0.50. Another embodiment according to the present invention concerns an instrument in which said means for cutting work comprises a cutting surface, said cutting surface consisting of a plane which is formed between said first extent and a first direction which is oriented at a first angle, where, in one embodiment according to the present invention, said first angle is less than 90° with respect to said first cross-sectional surface. The fact that said first angle is less than 90° with respect to said first cross-sectional surface means that said means for cutting work narrows towards the first upper end of the instrument. Moreover, said means for cutting work can have a configuration which is such that said instrument is not self-feeding. Such a configuration according to the present invention can be obtained, for example, by said means including said cutting surface, which cutting surface consists of a plane which is formed between said first extent and said first direction according to the above, and said cutting surface comprises an outermost part which has a second angle which is at 90° with respect to said first cross-sectional surface. The fact that said instrument is not self-feeding means that inadvertent cutting can be avoided during the internal working. A further embodiment according to the present invention concerns an instrument in which said first angle is less than 80°. The invention also includes further embodiments of said instrument in which said first angle is less than 70° or 60°. Yet another embodiment according to the present invention concerns an instrument in which said means for cutting work has a first length, during internal cutting work, which extends from said second upper end to said first upper end, i.e. from the upper end of the instrument shaft to the upper end of the instrument, there being a second ratio between said first length and said first external diameter of the instrument shaft, which second ratio is at least 0.1. The present invention also concerns instruments in which said second ratio is at least 0.2, 0.4, 0.8, 1.6 or 3.2. Said means for cutting work can include one or more cutting edges with the same or different cutting profiles. Yet another embodiment according to the present invention concerns an instrument in which said cutting surface is secured on said instrument at said second upper end. Since said cutting surface is secured on said instrument, said means for cutting work can have a form which consists of modifications of a block, half a round bar, a prism or another geometric shape, where said shape affords a substantial common surface with said first cross-sectional surface. Yet another embodiment according to the present invention concerns an instrument in which said means for cutting work is arranged pivotably at said second upper end. In this embodiment, on account of centrifugal force, said means comes to pivot out when the instrument rotates about the instrument shaft. The means can be made pivotable by said means being secured in place with, for example, a pin which is placed in the transverse direction of the instrument through the instrument shaft at said second upper end and asymmetrically through the means. The means can preferably be secured in such a way that a cutting in the instrument shaft affords a space and a guide for the means both in the inserted position and the outwardly pivoted position. Another embodiment according to the present invention concerns an instrument in which said instrument shaft is arranged with a measurement scale. The fact that the instrument shaft is arranged with a measurement scale means that it is possible to determine how deep a hole will be and at what depth in the bone tissue the internal working is to be carried out. A further embodiment according to the present invention concerns an instrument in which said instrument shaft is arranged with, for example, a sleeve which is adjustable in said longitudinal direction. With the adjustable sleeve, it is possible to set the depth at which internal working is to be carried out in the bone tissue. The sleeve has a through-hole in which the instrument shaft can freely rotate and run in the longitudinal direction of the instrument. The sleeve has a third upper end, and, from said third upper end, the upper part of the sleeve extends with a second external diameter, which second external diameter is smaller than a hole which has been made in the bone tissue, and a first height, which allow said third upper end to be inserted into a hole in the bone tissue to a depth which corresponds to said first height. Said first height is the same as or smaller than the thickness of the cortical part of the bone tissue. By adapting the second external diameter, it is possible to obtain satisfactory centering of the instrument shaft during internal working. Moreover, the sleeve has a third external diameter which is greater than the diameter of the hole in the bone tissue, and the sleeve thus bears closely on the hole. The sleeve also has a greatest part with a fourth external diameter and a second height, said greatest part making the sleeve easy to grip. By virtue of its design, the sleeve ensures that the instrument shaft of the surgical instrument is well guided during the internal working. When the surgical instrument is used for internal cutting of a hole in the bone tissue, for example for internal cutting of the trabecular part of the bone tissue, the sleeve bears against the cortical part of the bone tissue. During rotation of the instrument shaft, and as the latter at the same time is drawn in the longitudinal direction, the means for cutting work comes to cut the trabecular part of the bone tissue. When the means for cutting work reaches the cortical part of the bone tissue, a higher torsional moment is required for the rotation. A higher torsional moment can be observed by an operator who can then interrupt the internal cutting work and measure the thickness of the cortical part of the bone tissue using a measurement scale. During the cutting work, the sleeve centers the instrument shaft, so that a rotationally symmetrical cavity is obtained internally in the trabecular part of the bone tissue. When the work is completed, the sleeve is moved from its place on the hole in the bone tissue and the surgical instrument can be removed. Another embodiment according to the present invention concerns an instrument in which said construction for axial rotation of said instrument comprises a handle. The handle can have a shape and/or size which facilitates the axial rotation and it can be made of plastic, metal or another material permitting cleaning and sterilization, for example autoclaving. A further embodiment according to the present invention concerns an instrument in which said construction for axial rotation of said instrument comprises an attachment part for attaching it to a machine. Said machine can be a manually or mechanically operated drilling machine which is driven, for example, by air or electricity. In a further embodiment according to the present invention, said instrument can be autoclaved. Since the instrument is made up of a number of parts, all the parts of the instrument are able to undergo the necessary cleaning or sterilizing, for example autoclaving. Said instrument can be produced by chip removal work alone or in combination with welding or forging. The chip removal work can include, for example, turning, milling or grinding. DESCRIPTION OF THE FIGURES Figure 1a shows a plan side view of an embodiment of a surgical instrument according to the present invention, said instrument being shown here without the sleeve and the construction for axial rotation. Figure 1 b shows a partial enlargement of a portion of the surgical instrument 1 according to Figure 1a. Figure 2 shows a plan side view of the instrument in Figure 1a, the instrument having been turned 90° about the longitudinal direction of the instrument. Figure 3 shows a plan top view of the embodiment of the surgical instrument in Figure 1a. Figure 4 shows a cross section of a sleeve from the side, which sleeve is included in one embodiment of a surgical instrument according to the present invention. Figure 5 shows a cross section, from the side, of an embodiment of a surgical instrument according to the present invention and bone tissue, said instrument, which comprises a sleeve, internally working said bone tissue. Figure 6a shows a plan side view of a surgical instrument according to the present invention, on which said means for cutting work are pivotably arranged. Figure 6b shows a plan side view of the surgical instrument according to Figure 6a. Figure 6c is a partial enlargement of a portion of the surgical instrument according to Figure 6b. Figure 6d shows a plan top view of the surgical instrument according to Figure 6a. ILLUSTRATIVE EMBODIMENT Figure 1 a shows a plan side view of a surgical instrument 1 which has a longitudinal direction A and a transverse direction B and which comprises a first upper end 2, a first lower end 3, and an instrument shaft 4. The instrument shaft 4, which has not been shown here in its full length, has a second upper end 5, a second lower end 6, a first cross-sectional surface C (not shown in Figure 1 a) and a first external diameter D. Arranged at said second upper end 5 there is a means 7 for cutting work, and a construction for axial rotation of said instrument 1 can be attached at said first lower end 3. Said means 7 for cutting work comprises a cutting surface 8 secured to said instrument 1 , which cutting surface 8 is situated outside said first cross- sectional surface C (not shown in Figure 1a) of said instrument shaft 4 in relation to the transverse direction B. Said cutting surface 8 has a first length H which, during the internal cutting work, extends from said second upper end 5 to said first upper end 2. The instrument shaft 4 is also provided with a measurement scale 10. Figure 1b shows a partial enlargement of the surgical instrument 1 according to Figure 1a and makes clear that said cutting surface 8 consists of a plane which is formed between a first extent X (shown in Figure 2 but not in Figures 1 a or 1 b) and a first direction E which is oriented at a first angle F with respect to said first cross-sectional surface C (shown in Figure 3 but not in Figures 1a or 1b). Said first angle F constitutes the cutting angle of the instrument and is in the present case 60°. The instrument 1 also has a design which means that it is not self-feeding, because said cutting surface 8 comprises an outermost part 9 which has a second angle G which is 90° with respect to said first cross-sectional surface C. Figure 2 shows a plan side view of the instrument in Figure 1 a, said instrument 1 having been turned 90° about the longitudinal direction A of the instrument. The transverse direction B of the instrument and the first external diameter D of the instrument shaft have also been indicated here. Said cutting surface 8 consists of the plane which is formed between said first extent X and said first direction E (shown in Figure 1 b), and said cutting surface 8 comprises said outermost part 9. Figure 3 shows a plan top view of the embodiment of the surgical instrument 1 from Figure 1 a. The figure thus shows the first upper end 2 of the instrument, comprising instrument shaft 4 with its second upper end 5, with said first external diameter D, and means 7 for cutting work, said means 7 comprising a cutting surface 8 secured to said instrument 1. The figure also shows that part of the first cross-sectional surface C of the instrument shaft which is not covered by the means 7 for cutting work. Said cutting surface 8 is also partially situated outside said first cross-sectional surface C in relation to the transverse direction B. Said cutting surface 8 comprises a first extent X in said transverse direction B outside said first cross-sectional surface C, said first extent X being the greatest extent of said cutting surface 8 in the transverse direction B outside said first cross-sectional surface C. Figure 4 shows a cross section, from the side, of a sleeve 20 which is included in an embodiment of the surgical instrument 1. The sleeve 20, which has not been shown here in its full length, has a through-hole 21 in which the instrument shaft 4 can freely rotate and run in the longitudinal direction A. The sleeve 20 has a third upper end 22 and, from said third upper end 22, the upper part 23 of the sleeve extends with a second external diameter J (which is smaller than a hole in the bone tissue) and a first height K, both of which allow said third upper end to be introduced into a hole in bone tissue to a depth which corresponds to said first height K. Said first height K is the same size as or smaller than the thickness of the cortical part of the bone tissue. By adapting the second external diameter J, satisfactory centering of the instrument shaft is obtained upon internal working. Moreover, the sleeve 20 has a third external diameter M, which third external diameter M is greater than the diameter of the hole in the bone tissue, and the sleeve 20 thus bears closely on the hole. The sleeve 20 also has a greatest part 24 with a fourth external diameter N and a second height P, which greatest part 24 makes the sleeve 20 easy to grip. By means of its design, the sleeve 20 permits satisfactory guiding of the instrument shaft of the surgical instrument during the internal working. Figure 5 shows a cross-section, from the side, of a surgical instrument 1 , with an instrument shaft 4 and a means 7 for cutting work, and of bone tissue 30 with hole 31 , said instrument 1 comprising a sleeve 20 internally working a trabecular part 32 of said bone tissue 30. Said sleeve 20 bears against a cortical part 33 of said bone tissue 30. Upon rotation of the instrument shaft 4, and at the same time as it is drawn in the longitudinal direction, the means 7 for cutting work comes to cut the trabecular part 32 of the bone tissue 30. When the means 7 for cutting work reaches the cortical part 33 of the bone tissue 30, a higher torsional moment is required for the rotation. A higher torsional moment can be observed by an operator who can then interrupt the internal cutting work and measure the thickness of the cortical part 33 of the bone tissue 30 with the measurement scale 10. During the cutting work, the sleeve 20 centres the instrument shaft 4, so that a rotationally symmetrical cavity is obtained internally in the trabecular part 32 of the bone tissue 30. When the working is completed, the sleeve 20 is moved from its position on the hole 31 in the bone tissue 30, and the surgical instrument 1 can be removed. Figure 6a shows a plan side view of a surgical instrument 1 , said means 47 for cutting work being pivotably arranged at said second upper end 5. Here, the means 47 for cutting work is seen in the pivoted-out position. In the embodiment in which the means 47 is pivotably arranged, centrifugal force causes the means 47 to pivot out when the instrument 1 rotates about the instrument shaft 4. The means 47 is made pivotable by said means 47 being secured asymmetrically with a pin 40 which is placed through the instrument shaft 4 at said second upper end 5. Also shown is a first extent X in the transverse direction B which constitutes the greatest extent of the cutting surface 48 (shown in Figure 6b but not in Figure 6a) in the transverse direction B outside the first cross-sectional surface C. Figure 6b shows a plan side view of the surgical instrument 1 according to Figure 6a, where the instrument 1 has been turned 90° about the longitudinal direction A of the instrument, and a cutting 41 in the instrument shaft 4 can be seen which provides space for and guides the means 47 for cutting work both in the inserted and the outwardly pivoted positions. The cutting surface 48 of the instrument can also be seen here. Figure 6c is a partial enlargement of a portion of the surgical instrument 1 according to Figure 6b and makes clear that said cutting surface 48 consists of a plane which is formed between a first extent X (shown in Figure 6a but not in Figure 6c) and a first direction E which is oriented at a first angle F with respect to said cross-sectional surface C. Said first angle F constitutes the cutting angle of the instrument and is 60° here. Moreover, the instrument 1 has a design which means that it is not self-feeding because said cutting surface 48 comprises an outermost part 49 which has a second angle G which is 90° with respect to the first cross-sectional surface C. Figure 6d shows a plan top view of the surgical instrument 1 according to Figure 6a, where the whole of said cutting surface 48 can be seen, and also the first extent X.

Claims: PATENT CLAIMS 1. Surgical instrument (1 ) for internal working of holes (31 ) in bone tissue (30), said instrument (1 ) having a longitudinal direction (A) which is axial and a transverse direction (B) which is radial, and said instrument (1 ) comprising a first upper end (2), a first lower end (3) and an instrument shaft (4), said instrument shaft (4) having a second upper end (5), a second lower end (6), a first cross-sectional surface (C) and a first external diameter (D), with means (7; 47) which are arranged at said second upper end (5) and are intended for cutting work, and, at said first lower end (3), with a construction for axial rotation of said instrument (1 ), characterized in that said means (7; 47) for cutting work comprise a cutting surface (8; 48), which cutting surface (8; 48), during the internal cutting work, is partially situated outside said first cross-sectional surface (C) in relation to the transverse direction (B). 2. Instrument (1 ) according to Claim 1 , characterized in that, during the internal cutting work, said cutting surface (8; 48) has a first extent (X) in said transverse direction (B) outside said first cross-sectional surface (C), and in that there is a first ratio (X/D) between said first extent (X) and said first diameter (D), said first ratio (X/D) being at least 0.15. 3. Instrument (1 ) according to either of the preceding claims, said cutting surface (8; 48) having a first extent (X) in said transverse direction (B) outside said first cross-sectional surface (C), characterized in that said cutting surface (8; 48) consists of a plane which is formed between said first extent (X) and a first direction (E) which is oriented at a first angle (F), which first angle (F) is less than 90° with respect to said first cross-sectional surface (C). 4. Instrument (1 ) according to Claim 3, characterized in that said cutting surface (8; 48) comprises an outermost part (9; 49) which has a second angle (G) which is 90° with respect to said first cross-sectional surface (C). 5. Instrument (1 ) according to any of the preceding claims, said means (7; 47) for cutting work having a first length (H), during internal cutting work, which extends from said second upper end (5) to said first upper end (2), and there is a second ratio (H/D) between said first length (H) and said first external diameter (D) of the instrument shaft, which second ratio (H/D) is at least 0.1. 6. Instrument (1) according to any of the preceding claims, characterized in that said cutting surface (8) is secured on said instrument (1 ) at said second upper end (5). 7. Instrument (1) according to any of Claims 1 to 5, characterized in that said means (47) for cutting work is arranged pivotably at said second upper end (5). 8. Instrument (1) according to any of the preceding claims, characterized in that said instrument shaft (4) is arranged with a measurement scale (10). 9. Instrument (1 ) according to any of the preceding claims, characterized in that said instrument shaft (4) is arranged with a sleeve (20) which can be adjusted in said longitudinal direction (A). 10. Instrument (1 ) according to any of the preceding claims, characterized in that said construction for axial rotation of said instrument comprises a handle. 11. Instrument according to any of the preceding claims, characterized in that said construction for axial rotation of said instrument comprises an attachment part for attaching it in a machine. 12. Instrument (1 ) according to any of the preceding claims, characterized in that said instrument permits necessary cleaning or sterilizing, for example autoclaving.

Inventors: NILSSON ANDERS, PERSSON ANDERS L, NILSSON, ANDERS, PERSSON, ANDERS, L.
Applicants: ARTIMPLANT AB, NILSSON ANDERS, PERSSON ANDERS L, NILSSON, ANDERS, PERSSON, ANDERS, L.
Application year: 2001
Main classification: A61B17
IPC codes: A61B17, A61C8