MXPA97008593A - Instrument guide of perforac - Google Patents

Abstract

The present invention relates to a drilling guide instrument for guiding a drilling tool when a longitudinal hole is drilled through the neck (collum femoris) of a human femur, after resection of the head (caput) of the collum at length of the cutting plane (P), characterized in that: a drilling guide is provided with a base member and arranged to guide the drilling tool along the drilling axis (BB) in relation to the base member, the member base is intended to be applied against the end cutting surface of the collum defining the cutting plane (P) to obtain a predetermined orientation of the drilling axis (BB) in relation to the cutting plane (P), and a positioning member, the which extends from the drill guide which is intended to be in contact with the periphery of the narrowest portion of the collum in at least two circumferentially spaced contact positions, for locate the drilling axis (B-B) at a minimum distance from the periphery of the narrowest portion in the coll

Description

PERFORATION GUIDE INSTRUMENT TECHNICAL FIELD OF THE INVENTION The invention relates to the field of permanent walking of hip joint prostheses in the articulation of the human chain. More specifically, the invention relates to a drilling guide instrument for guiding a drilling tool when a longitudinal hole is drilled through the neck. { coll um femoris) of the human femur, after a resection of the head (caput) of the collum. The invention also relates to the use of such an instrument, as well as a method for drilling such an orifice.

BACKGROUND OF THE INVENTION The invention is special, but not exclusively, applicable to the walking of hip joint prostheses of the type described in WO 93/16663, the technical background of the invention will be described with specific reference to this document and the problems encountered when assembling a hip joint. Hip joint prosthesis of the type described herein. However, the invention is REF: 25938 applicable also to other types of hip joint prosthesis. WO 93/16663 discloses a hip joint prosthesis comprising a joint part for a spherical unit designed to be anchored in the neck of the human femur. { coll um femoris). The joining part comprises a part for supporting a sphere or caput which is intended to be attached to the collum after the head of the collum has been resected. The joining part also comprises a positioning member having two main parts, namely a first part which extends through a hole extending from the collum towards the outer side of the femur, and a second part similar to a pin that intends to be fixed to the cylindrical cavity cut in the cancellous bone of the collum. A hip joint prosthesis of this type is illustrated in Figure 1 of the accompanying drawings. Additional examples of the hip joint prosthesis of the prior art are described in WO 93/01769 and WO 89/11837. In order to obtain a strong movement of the prosthesis, the second part of the pin-like positioner can be mounted with the inner side of the cortical bone in the collum, as described in general terms in WO 93/16663, since a contact Direct with the cortical bone will reduce the risk of mechanical loosening of the prosthesis. However, any perforation of the cortical bone of the collum should be avoided, as discussed in the same document. Especially, the cortical bone should not be pierced by the cylindrical cavity or by the part similar to a pin received in it. Since the cylindrical cavity is concentric with the drilled hole and is actually cut in the collum with the help of the drilled hole as a guide channel, the longitudinal hole must be drilled through the collum along an axis having an orientation predetermined position and in relation to the collum to obtain the desired coupling between the part of the positioner similar to a pin and the cortical bone. Therefore, an object of the invention is to allow high-precision drilling of a longitudinal hole through the collum of the human femur along a drilling axis having a predetermined orientation and a predetermined position relative to the collum. . It is also an object of the invention to allow fast and reliable high precision drilling of this type. Especially, an object of the invention is to orient and position the drilling axis in such a way that a hip joint prosthesis anchored posteriorly in the collum is firmly coupled to the cortical bone in the collum, while reducing the risk of any perforation of the cortical bone. A particular object of the invention is to provide a drilling guidance instrument by means of which both the orientation and the placement of the drilling axis can be determined in relation to the collum in a reliable and accurate manner, and which can be used to guide a drilling tool. drilling or equivalent along the drilling axis in this way established.

DESCRIPTION OF THE INVENTION These and other objects of the invention are achieved by means of a guide instrument and method of perforation, as well as the use of such instrument, which has the features set forth in the appended claims. Thus, a drilling guide instrument according to the invention comprises a drilling guide provided with a base member and arranged to guide the drilling tool along a drilling axis in relation to the base member, the member base is intended to be applied against an extreme cutting surface of the collum that defines a cutting plane, along which the head. { caput) of the coll um has been removed, to obtain a predetermined orientation of the drilling axis in relation to the cutting plane. The instrument further comprises a positioning member, which extends from the piercing guide and is intended to be in contact with the periphery of the narrowest portion of the collum in at least two circumferentially spaced contact positions, to locate the axis of perforation at a minimum distance from the periphery of the narrowest portion of the collum. With the aid of the instrument according to the invention, a hole can be drilled to receive a positioning member of a hip joint prosthesis longitudinally through the femoral collum along a drilling axis having the correct orientation as well as the correct position in relation to coll um. The instrument according to the invention should be used after a resection of the head. { caput) of the coll um along a plane of cut, the instrument uses this plane of cut as a reference plane to establish the correct orientation of the axis of perforation in re la: ': ion L coll um. Accordingly, the base member of the perforation guide serves to orient the guide, ie the drilling axis, in relation to the end cutting surface of the collum. In a preferred embodiment of the invention, the drilling axis is oriented at right angles to the cutting plane. Since the drill guide instrument uses the cutting plane as the reference plane, the resection of the head of the collum should preferably be made exactly at predetermined angles to the longitudinal extension of the collum. Swedish patent application SE 9501828-9, entitled "guide instrument for cutting", describes a cutting guide instrument suitable for this purpose. In a preferred embodiment of the instrument, the drilling guide is provided with a guide channel for receiving and guiding the drilling tool along the longitudinal axis of the drilling channel which coincides with the drilling axis. However, the statement that the drill guide is intended to guide a drilling tool along a drilling axis relative to the base member means that it encompasses not only the alternative that the drilling tool is separate from the drilling tool. invention, as will be described below with reference to the preferred embodiment of the instrument, but also the alternative that the drilling tool be an integral part of the instrument. In this way, the piercing guide may also comprise a template for supporting the piercing tool and guiding it in relation to the base member. To also establish the correct position of the drilling axis in relation to the collum, especially a position that results in a firm coupling between the prosthesis positioner part and the cortical bone without any perforation of the latter, the instrument according to The invention comprises the aforementioned positioning member which, in use, extends from the drilling guide, beyond the cutting plane and towards the collum, to come into contact with the periphery of the narrowest portion of the collum in at least two circumferentially spaced contact positions. As a result the drilling axis can be placed at a predetermined minimum distance from the periphery of the narrowest portion of the collum. In the preferred embodiment of the invention, the positioning member intends to be put in simultaneous contact against the collum in the contact positions. However, the positioning member can also be arranged to contact only one contact position at a time. It is preferred that the positioning member be releasably connected to the instrument, to be replaced with other positioning members corresponding to different values of the minimum distance mentioned above. This embodiment is advantageous since one and the same piercing guide can be used for femoral necks of different sizes. In this mode, the minimum distance is determined first by measuring the size of the narrowest portion of the coll um. Next, a positioning member corresponding to the minimum distance determined from a set of different positioner members will be selected and mounted on the instrument. It is also preferred that the positioning member be movable relative to the base member transversely to the cutting plane, to allow adjustment of the positioning member to a position in which portions of the positioning member that are in contact with the periphery of the coll um are at a level with the narrowest portion of it. In addition, the instrument according to the invention preferably comprises means for temporarily fixing the base member in relation to the collum. Considering that the cutting plane that should be used as a reference plane by the base member, such fixing means can be advantageously adapted to hold the base member against the cutting end surface of the collum defining the plane of reference. cut. A method according to the invention for drilling a longitudinal hole through the neck. { coll um femoris) of the human femur, after resection of the head. { caput) of the coll um along the cutting plane, is characterized by the steps of: applying a drilling guide instrument against the extreme cutting surface of the coll um that defines the cutting plane, using the cutting end surface as plane reference for placing a drilling axis of the drilling guide instrument in a predetermined orientation relative to the cutting plane, and using at least two circumferentially spaced positions of the periphery of the narrowest portion of the collum as reference positions to locate such drilling shafts at a minimum distance from the periphery of the narrowest portion of the collum, and pierce the longitudinal bore by means of a drilling tool guided by the drilling guiding instrument thus applied along the oriented drilling axis and located. Preferred modes of implementation of the method of the invention are set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view of a hip joint prosthesis of the prior art anchored in the collum of a human femur along a perforated orifice. The Figure is a perspective view of a preferred embodiment of the piercing guide instrument according to the invention, which is mounted in the position of the piercing guide on a cutting end surface of a femoral collum. Figure 3 is a side, side view, taken along line III-III in Figure 2, a positioning member of the instrument being removed for clarity. Figure 4 is a side, side view, taken along the line IV-IV in Figure 3, which includes the positioning member. Figure 5 is a perspective view of a test and control device to be used in association with the instrument shown in Figures 2-4.

DETAILED DESCRIPTION OF A PREFERRED MODE OF THE INVENTION To illustrate the advantages of the present invention, reference is first made to Figure 1, which illustrates the hip joint prosthesis of the type described in W093 / 16663. The prosthesis comprises a first cylindrical fastening part 1, and a second fastening part similar to a plug 2 containing a sphere or caput 3. The first fastening part 1 is made in several versions of different length, while the second part Clamp 2 similar to a dowel is made in several versions of different diameter. The first fastening part 1 has been placed in a hole 4, which has been pierced longitudinally through the cancellous bone of the femoral collum 5 along a drill axis BB by means of a drilling tool (reference numeral 24 in Figure 2) having a diameter corresponding to that of the first fastening part 1. The second fastening part 2, similar to a dowel, has been placed in a cylindrical cavity 6 cut in the canceled bone of the collum 5 for to be coaxial with the perforated orifice 4. The cylindrical cavity 6 has been cut longitudinally along the drilling axis BB in a direction from the head 8 by means of a rotating cutting tool (not shown). The cutting tool is available in various sizes, each corresponding to a specific diameter of a second fixing part 2, similar to a pin, and comprises an elongated guide element to be inserted and guided by the perforated hole 4. The second part 2, similar to a pin, is delimited by a circumferential rim 7 which limits the insertion in the cavity 6, the rim 7 is in contact with the end cutting surface 11 which defines a cutting plane P, along of which the head 8 of collum 5 has been removed. Reference is made to W093 / 16663 for additional details of this prior art prosthesis shown in Figure 1 and the running thereof. In Figure 1, the orientation of the fixing parts 1 and 2 in relation to collum 5, and especially cortical bone 10, differ from that which has been previously described in W093 / 16663. More specifically, the second fixation part, similar to a pin, is firmly coupled, along its entire length, to the cortical bone 10 in a specific area 12 located along the mid aspect of the transition zone between the coll um femoral 5 and the femoral axis 9. Since the total object is to maximize the support for the fixation parts 1, 2 sinpenetrate the cortical bone 10, the area 12 of the cortical bone 10, which is relatively thick as illustrated in Figure 1 is advantageously used to couple and support the second fixing part 2, similar to a pin. In this way, in order to ensure a strong anchoring of the prosthesis, both the orientation and the position of the drilling axis B-B are preferably established with a high degree of accuracy during the drilling operation., since the hole 4 is subsequently used as a guide channel for the cutting tool when the cavity 6 in the canceled bone of the collum 5 is cut, as stated above. The orientation and / or position of the drill shaft BB could be incorrect during the drilling of the hole 4, the cylindrical periphery of the cut cavity 6 will be (i) totally or partially separated from the advantageous area 12 of the cortical bone 10, resulting in a null or only partial walking of the second fixation part 2, similar to a dowel, in the cortical bone 10, especially in the advantageous area 12, or (ii) displaced towards the cortical bone to such a degree that the latter is penetrated, either by the cavity 6 or by the second fixing part 2 similar to a pin. Due to the risk of penetration of the cortical bone, the situation is complicated due to the fact that collum 5 normally has a funnel shape adjacent to the cutting plane P, as is illustrated more clearly in Figure 3, in which dotted line N indicates the narrowest part 13 of col l um 5. Due to the funnel shape of coll um 5, the correct positioning of drilling axis BB in relation to coll um 5, that is, that the correct placement of the point intersection of the drill shaft BB and the cutting plane P, can not be determined based on the profile section of the end cutting surface 11, since this is the size of the narrowest part 13 that determines the maximum allowable size of the cutting tool to be used, and consequently the maximum possible diameter of the second fixing part 2, similar to a pin.

In Figure 1, the cutting plane P has been chosen to make a predetermined cutting angle ac with the femoral axis 9, the main longitudinal direction of which is identified by a straight line AA, and must be located at a predetermined cutting level. Lc with respect to the end of the head 8. The resection of the head 8 along such a well defined cutting plane can preferably be effected by means of a cutting guide instrument as described in SE 9501828-9 mentioned above. Referring now to Figures 2-4, the structure and use of the preferred embodiment of the piercing guide instrument according to the invention will be described below, similar parts in Figure 1 and Figures 2-4 have the same references numerical Generally, the instrument according to the invention comprises a piercing guide 20 having a base member 21 and a positioning member 22 connected to the piercing guide 20. In the preferred embodiment shown, the piercing guide 20 is in shape of a tubular cylinder, the inner periphery of which defines a guide channel 23 for receiving and guiding the drilling tool 24 along the drilling axis BB. In Figure 2, the drilling tool 24 is a trepadora, although any other drilling tool can also be used. The base member 21 of the drill guide 20 is in the form of a plate having a flat contact surface 25 covering essentially the entire cutting end surface 11. One end 26 of the cylinder 20 is fixedly connected at right angles to the opposing surface 27 of the contact plane 21, which is provided with a through hole (not shown) that coincides with the guide channel 23 of the cylinder 20. The positioning member 22 is an interchangeable part of the piercing guide instrument and comprises a sleeve of cylindrical connection 28, which is loosely placed on the cylinder 20 and is provided with two essentially U-shaped locating arms 29. In use, the locating arms 29 extend from the connecting sleeve 28, beyond the plate base 21 and towards coll um 5, as shown in Figures 2 and 4. The U-shaped positioning arms 29 are essentially orthogonal and extend in radial planes r Specimens of the drilling axis B-B. The distal ends of the positioning arms 29 form contact ends 30, both of which are for contacting the periphery of collum 5 in the narrower portion 13 thereof, as indicated by dotted line N in the Figure 2. The preferred embodiment of the instrument comprises a set of interchangeable positioning members 22, each of which has a connecting sleeve 28 with two positioning arms 29. The positioning members 22 of the set differ only in the radial distance, measured from their ends of contact 30 to the central axis of the connecting sleeve 28. In other words, the two contact ends 30 and the central axis of the connecting sleeve 28 define circles of different diameters for each of the positioning members 22 of the set. As an example, such a set may comprise four different positioning members 22, which correspond to diameters of 16 mm, 17 mm, 18 mm and 19 mm. Figure 5 illustrates a control device comprising a cylindrical shaft 31 and a stepped conical base 32 and adapted to verify that the contact ends 30 of each positioning member 22 of such four-part set are located at the correct distance from the central axis of the connecting sleeve 28. Figures 2 and 3 illustrate a situation in which a positioning member 22 of size "18" (diameter = 18 mm) has been selected, then the size of the narrower portion 13 of the collum 5 has been measured in N being approximately 24 mm. To obtain, say, a safety margin of 3 mm for the thickness of the cortical bone 10 in the narrowest portion 13 of the coli um, the diameter of the second fixing part 2, similar to a plug, should be selected so that it is 18 mm. Thus, by selecting a positioning member 22 of size "18", the drill axis BB will be located at a minimum distance of 18 mm / 2 = 9 mm from the outer periphery of the narrower portion 13 of coll um 5. In this example, the cavity 6 for the fixing part 2 similar to a pin can be cut with a cutting tool having a diameter of 18 mm or slightly smaller, depending on whether the second fixing part 2, similar to a pin, will remove any additional bone tissue when inserted into the cavity 6. In the preferred embodiment of Figures 2-4, the base plate 21 is held against the end cutting surface 11 of the collum 5 by means of two rotating jaws 33, more illustratively illustrated in Figure 3, each jaw is rotatably connected to the base plate 21 at 34 to move rotatably in a plane perpendicular to the base plate 21. The jaws 33 comprise teeth coupling ends. two, in cooperation, 35, which can be clamped against the collum 5 by forcing the opposite ends 36 apart with the help of a separate manual clamping tool 37 having conventional means 38 for immobilizing the tool in a clamped position. The aforementioned funnel shape of the collum 5 in combination with the rotary movement of the jaws 33 will also affect the fastening of the base plate 21 downwards in Figure 3 against the end cutting surface 11, to ensure the correct orientation of the cylinder 21 in relation to the cutting plane P. The following steps are carried out when the previous drilling guide instrument is used. After resection of the head 8 of collum 5, the size of the narrowest portion 13 of collum 5 was measured. The position of the narrowest portion 13 can be marked by a line (N). In oase to this measurement, a positioning member 22 corresponding to a convenient size of the second fixing part 2, similar to a plug, is selected to be mounted on the cylinder 20. Subsequently, the contact surface 25 of the base plate 21 It is coupled with the end cutting surface 11 of the collum 5. The positioning member is manually moved along the cylinder 20 from the base plate 21, as illustrated in Figure 4 to a position in which the contact ends 30 of the positioning arms 29 are on a level (on the N line) with the narrowest portion 13. However, the indication line can be dispensed with, since the narrower portion 13 of the collum can be easily located by displacing the member positioner 22 along the cylinder 20 while the two contact ends 30 are constantly pushed towards the contact with the periphery of the collum. Preferably, the connecting sleeve 28 is rotated about the cylinder 20 to an angular position in which the contact ends 30 of the arms 39 are at equal angular distances from a plane of symmetry of the collum, as indicated by means of a dotted line L in Figure 2. The drill shaft BB is now correctly oriented and positioned, the entire instrument is temporarily fixed to the collum 5 by means of the jaws 33 and the clamping tool 37. The drilling tool 24 can now be received and guided by the drill channel 23 to pierce the hole 4 longitudinally through the collum 5, after which the drill guide instrument is removed. Finally, the cavity 6 is cut into the cancellous bone as described above, using the perforated hole 4 as a guide channel for a cutting tool. Various modifications of the embodiment described above are conceivable within the scope of the appended claims. For example, the drill guide can be formed by numerous coaxial rings forming a guide channel for a drilling tool. further, the drilling tool can be formed integrally with the instrument, and in that case the structure of the drill guide can differ essentially from that of the mode shown in the Figures. In a simpler mode, the positioning member can be fixedly connected to the drill guide. As for the base member, other alternatives to the plate could be envisaged, for example, some form of tripod arrangement for orienting the drill guide in relation to the end cutting surface. Finally, the contact ends 30 of the positioning member could be in the form of a continuous ring in contact with the collum along the N. line.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (20)

1. A drilling guide instrument for guiding a drilling tool when a longitudinal hole is drilled through the neck. { coll um femoris) of a human femur, after the resection of the head. { caput) of the collum along the cutting plane (P), characterized in that: a drilling guide is provided with a base member and arranged to guide the drilling tool along the drilling axis (BB) in relation to the base member, the base member is intended to be applied against the cutting end surface of the collum which defines the cutting plane (P) to obtain a predetermined orientation of the drilling axis (BB) in relation to the cutting plane (P) ), and a positioning member, which extends from the drilling guide which is intended to be in contact with the periphery of the narrowest portion of the collum in at least two circumferentially spaced contact positions, to locate the drilling axis (BB) at a minimum distance from the periphery of the narrowest portion in the collum.

2. The instrument according to claim 1, characterized in that the positioning member is detachably connected to the insulator, to be replaced with other positioning members corresponding to different values of the minimum distance.

3. The instrument according to any of the preceding claims, characterized in that the drilling guide is provided with a drill channel for receiving and guiding the drilling tool along the drilling axis (B-B).

4. The instrument according to any of the preceding claims, characterized in that the positioning member moves relative to the base member transversely to the cutting plane (P).

5. The instrument according to claims 3 and 4, characterized in that the drill guide comprises a tubular member, which is connected at one end to the base member and having an internal cylindrical surface which defines the guide channel, and a surface cylindrical external along which a connecting sleeve of the positioning member moves.

6. The instrument according to any of the preceding claims, characterized in that the positioning member rotates around the drilling axis (B-B;

7. The instrument according to any of the preceding claims, characterized in that the base member has a flat contact surface of sufficient dimensions to cover at least a greater part of the cutting end surface of the collum defining the cutting plane (P ).

8. The instrument according to any of the preceding claims, characterized in that the drilling axis (B-B) is oriented at right angles to the base member.

9. The instrument according to any of the preceding claims, characterized in that it also comprises means for fixing the base member in relation to the collum.

10. The instrument according to claim 9, characterized in that the fixing means comprise at least two jaws connected in an articulated manner to the base member to rotate transversely to the cutting plane (P) to be secured against the outer periphery of the coil um.

11. The instrument according to claim 10, characterized in that the jaws are hingedly connected to the base member in such a way that, when they are clamped to the collum, they press the base member against the end cutting surface of the collum.

12. A method for drilling a longitudinal hole through the neck. { coll um femori s) of the human femur, after the resection of the head. { caput) of the colium along a cutting plane (P), characterized by the steps of: applying a drilling guide instrument against an end cutting surface of the collum defining the cutting plane (P), using the cutting end surface as a reference plane to bring a drill axis (BB) of the drill guide instrument to a predetermined orientation relative to the plane of cut (P), and using at least two circumferentially spaced positions of the periphery from the narrowest portion of the collum as reference positions to locate the drilling axis (BB) at a minimum distance from the periphery of the narrowest portion of the collum, and to drill such a longitudinal hole by means of a guided cutting tool by the drilling guide instrument thus applied along the drilling axis (BB) oriented and located.

13. The method in accordance with the claim 12, characterized in that it also comprises the step of fixing the drill guide instrument in relation to the cutting plane before the step of drilling the longitudinal hole.

14. The method in accordance with the claim 13, characterized in that the fixing step comprises the sub-step of pressing the drilling guide instrument against the cutting end surface of the collum.

15. The method according to any of claims 12-14, characterized in that the drilling guide instrument comprises a base member and a guide member connected thereto, the base member is applied against the cutting end surface and the drilling tool it is guided through an internal guide channel of the guide member during the drilling step.

16. The method according to any of claims 12-15, characterized in that the drilling axis (B-B) is oriented at right angles to the end cutting surface.

17. The method according to any of claims 12-16, characterized in that the weight of using 'at least two circumferentially spaced positions of the periphery of the narrowest portion of the collum as reference positions to locate the drilling axis (B-B) at a minimum distance from the periphery of the narrowest portion of the collum, comprises the sub-step of carrying a positional member of the piercing guide instrument in contact with the periphery of at least two circumferentially spaced positions.

18. The method according to claim 17, characterized in that the weight of placing the positioning member in contact with the periphery of the collum comprises the sub-step of moving the positioning member relative to the cutting end surface to locate the narrowest portion of the coll. um.

19. The method according to claim 17 or 18, characterized in that the positioning member is detachably connected to the instrument, the method further comprising, before the step of contacting the positioning member with the periphery of the coil um, the step of determining the minimum distance measuring the size of the narrowest portion of the collum, and the step of selecting, on the basis of the instrument, the positioning member of a set of different positioning members corresponding to different sizes of the narrowest portion of the collum.

20. The use of an instrument according to any of claims 1-11 for drilling a longitudinal hole through the neck. { coll um femori s) of the human femur to anchor a hip joint prosthesis in the perforation, where: the head. { caput) of the coll um is removed along a cutting plane (P), which defines an extreme cutting surface of the coil um, the base member of the drill guide is applied against the cutting end surface to obtain a predetermined orientation of the drilling axis (BB) in relation to the cutting plane, the positioning member is brought into contact with the periphery of the narrowest portion of the collum in at least two circumferentially spaced contact positions, to locate the drilling axis (BB) at a minimum distance from the periphery of the narrowest portion of the collum, and the longitudinal hole is drilled by means of a drilling tool guided by the drill guide thus applied along the drilling axis (BB) oriented and located.