Joint prosthesis and use of screw tool for positioning members thereof

(54) Title: Joint prosthesis and screw tools for affixing parts thereof (56) Published publications: US Al 5 147 386, US Al 5 580 352, US Bl 6 827 722 (47) Abstract:

The present invention relates to a joint prosthesis having two prosthetic portions (2, 3) intended to be affixed to different bones {39; 41, 42> at one joint (38). Each prosthetic portion (2, 3) has a first and a second, respectively. other screw-like parts (4, 5), which are intended to be screwed to the respective legs (39; 41, 42). One of the prosthetic members (2) has a hinge-carrying portion (6) and the other prosthesis (3) has a hinge-bearing portion (7). The hinge display portion (6) has a mounting pin (22) which is inserted into a projecting heel (10) of the first screw-like portion (4) for affixing the hinge display portion (6) to it and the hinge bearing portion (7) has a fastening pin (27) which is inserted into a first heel (11) of the second screw-like part (5) for affixing the articulated ball-bearing part (7) thereto. In each first resp. second screw-like part (4, 5) is provided with at least one second heel (30 and 30, respectively). 33), which is designed to allow a screw pin (31) of a screw tool (32) to be inserted therein to screw the first and second screws, respectively. second helical portion (4, 5) at respective legs (39; 41, 42).

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Summary:

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The present invention relates to a joint prosthesis having two prosthetic portions (2, 3) intended to be affixed to different legs (39; 41, 42) at a joint (38). Each prosthetic portion (2, 3) has a first and a second, respectively. other screw-like parts (4, 5), which are intended to be screwed to the respective legs (39; 41, 42). One of the prosthetic members (2) has a hinge-carrying portion (6) and the other prosthesis (3) has a hinge-bearing portion (7). The hinge display portion (6) has a mounting pin (22) which is inserted into a first bore (10) of the first screw-like portion (4) for affixing the hinge housing portion (6) to it and the hinge bearing portion (7) has a fastening pin (27) which is inserted into a first hole (11) in the second screw-like part (5) for affixing the articulated ball-bearing part (7) thereon. At least one second hole (30 and 30, respectively) is provided in each first and second screw-like part (4, 5). 33), which is designed to allow a screw pin (31) of a screw tool (32) to be inserted therein to screw the first and second screws, respectively. second helical portion (4, 5) at respective legs (39; 41, 42).

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The present invention relates to a joint prosthesis having two prosthetic portions which are intended to be affixed to different bones at one joint, and each prosthetic portion having a first and a second portion respectively. other screw-like parts which are intended to be screwed to the respective legs. One of the prosthetic parts has a hinge-carrying part and the other prosthesis has a hinge-like part. The hinge bearing portion has a mounting pin which is inserted into a first hole in the first screw-like portion to affix the hinge bearing portion thereon and wherein the hinge bearing portion has a mounting pin which is inserted into a first hole in the second screw-like portion. apply the articulating part to it. The invention also relates to the use of a screw tool for applying parts of the joint prosthesis.

In US 5,147,386, a joint prosthesis is described with two screw-like parts which are anchored to the respective legs to be joined by the prosthesis. The joint consists of a joint 528 545

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bowl and a hinge ball, the end of the hinge bearing portion being secured to one of the screw-like parts by press fit. To screw the screw-like parts there are grooves for a screw tool in outer end surfaces thereof, which means that the grooves will form sharp edges that can damage adjacent tissues, which is of course particularly inappropriate.

The object of the present invention is to eliminate the problem that the screw-like parts of the prosthetic members have outer grooves that form sharp edges. This is achieved by having the prosthesis exhibiting the features which are essentially apparent from the following claim 1.

By inserting the screw-like parts of the prosthesis inside its holes for articulated cups. If the ball bearing parts have interiors, specially designed for holes in a screw tool, the screw tool can be inserted into its holes to screw the screw-like parts to the legs in question and avoid external grooves that can lead to damage.

The invention will be explained in greater detail below with reference to the accompanying drawings, in which Figure 1 shows a side view of a wrist prosthesis according to the invention as implants in a wrist;

Figure 2 is a sectional view showing a first screw-like part included in the wrist prosthesis of Figure 1;

Figure 3 shows a section along line III-III of the first screw-like part of Figure 2;

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Figure 4 with. a section shows a second screw-like part included in the wrist prosthesis of Figure 1;

Figure 5 shows a section along the line VV of the second screw-like part of Figure 4;

Fig. 6 with a side view shows a hinge showing portion included in the wrist prosthesis of Fig. 1;

Fig. 7 with a side view shows an articulating part included in the wrist prosthesis of Fig. 1; and FIGS. 8-12 show different torques when applying screw-like parts included in the wrist prosthesis of FIG.

The drawings show a wrist prosthesis 1 having a first prosthesis portion 2 and a second prosthesis portion 3. The first prosthesis portion 2 has a first screw-like portion 4 and the second prosthesis portion 3 has a second screw-like portion 5. In addition, the first prosthesis portion 2 has a hinge-like portion 6 and the second prosthesis portion 3 additionally has an articulating portion 7. other screw-like parts 4, 5 have an attachment portion 8 and 8, respectively. 9 which in the embodiment shown has a first hole 10 and 10 respectively. 11. The first hole 10 in the first screw-like part 4 extends as a depression at a first end edge 12 at which said part 4 has the largest diameter in an axial direction against a second end edge 13 of said part 4 at which part 4 has the smallest diameter. . The first bore 10 is preferably centered with a geometric center line CL1 extending in the axial direction of the part 4.

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The first hole 11 of the second screw-like part 5 extends as a depression at a first end edge 14 at which said part 5 has the largest diameter in an axial direction towards a second end edge 15 of said part 5 at which part 5 has the smallest diameter. The first hole 11 is centered with a geometric center line CL2 extending in the axial direction of the part 5.

The first hole 10 in the first screw-like part 4 has its largest diameter at the first end edge 12 and its side walls 16 have a conical shape, the smallest diameter of which is at the bottom 17 of the hole 10, i.e. the first hole 10 tapered towards its bottom 17 form.

The first hole 11 in the second screw-like part 5 has the largest diameter at the first end edge 14 and its side walls 18 have a conical shape, the smallest diameter of which is at the bottom 19 of the hole 11, ie the hole 11 has a tapered shape towards its bottom 19.

The hinge display portion 6 has a hinge bowl 20 which forms a concave hinge surface 21. From the outside of the hinge 20, a fastening pin 22 projects in an axial direction. The retaining pin 22 has an axial tapered exterior in the direction of its end edge 23 and the shape and dimension of the retaining pin 22 and the shape and dimension of the first bore 10 of the first screw-like portion 4 are so selected that they can form in an axial direction by compression. a press fit, ie such a joint which allows the hinge-carrying portion 6 and the first screw-like part 4 to be brought together by compression.

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The articulating member 7 has a substantially spherical articulating ball 25 which forms a convex articulating surface 26 in such a way that it fits in the articulating surface 21 of the articulation cup 20 so that said articulating surfaces 21, 26 can slide against each other and enable the articulability of the articulation. From the hinge ball 25 a fastening pin 27 projects in an axial direction and this fastening pin 27 has a tapered exterior 29 in an axial direction towards its end edge 28. The shape and dimension of the fastening pin 27 and the shape and dimension of the first bore 11 of the second screw-like part 5 are selected so that, by compressing in an axial direction, they can form a press fit, ie such a joint that permits the ball-bearing part 7 and the other screw-like part 5 by compressing can be made to adhere to each other.

The first screw-like part 4 has at least a second hole 30 which is designed to allow a screw pin 31 of a screw tool 32, e.g. a screwdriver, can be inserted into this hole 30 to screw the first screw-like part 4 to the leg in question. The second screw-like part 5 has at least one second hole 33 which is designed to allow the screw pin 31 of the screw tool 32 to be inserted into this second hole 33 to screw the second screw-like part 5 to the legs in question.

Each other hole 30 and 30, respectively. 33 are preferably arranged inside each first and second, respectively. second screw-like part 4, 5 first holes 10 and 10, respectively. 11. The screw pin 31 of the screw tool 32 is designed so that it can be inserted into and engaged with the second hole 30 and 30, respectively. 33 by passing through the first hole 10 and 10, respectively. 11 without damaging the side walls 16 and 11, respectively. 18 to these holes 10 and 10 respectively. 11th

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As shown in Figures 2 and 4, each other hole 30 and 30 may, respectively. 33, for example, be arranged at the bottom 17 and 17 respectively. 19 to respective first holes 10, 11.

Each other hole 30 and 30, respectively. 33, like the first hole 10 and 10 respectively. 11 suitably centered with, respectively. center line CL1, CL2. Further, the second hole 30 and 30, respectively. 33 being a non-round hole, e.g. a multi-hole, such as a hexagon hole or the like. The screw pin 31 of the screw tool 32 is of course adapted to the second hole 30 and 30, respectively. 33 shape so that one can turn respective screw-like parts 4, 5 by turning the screw tool 32 to screw them into the respective legs.

Every first resp. second screw-like portions 4, 5 are preferably externally tapered from the first end edge 12 and 12, respectively. 14 in the direction of the second end edge 13 and 14, respectively. The conical shape preferably extends, but not necessarily, all the way between said first and second end edges 12, 14 and 12, respectively. 13, 15. Furthermore, each first and second display respectively. other screw-like parts 4, 5 outer threads 34 and 5, respectively. 35, which preferably has self-tapping properties.

As shown in the drawings, the outer threads 34 and 2, respectively. 35 at the first end edge 12, respectively. 14 and terminate a distance from the other end edge 13 and 14, respectively. 15, so that the tip end of the first and second ends, respectively. other screw-like parts 4, 5 become thread-free.

Every first resp. other screw-like parts 4, 5 may be thread-free at elongate parts 4a and 5, respectively. 5a, extending in axial direction along the first and second axes, respectively. other screws 528 545

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similar parts 4, 5 to divide the outer threads 34 and 5, respectively. 35 in several, for example, four, thread sections.

Every first resp. other screw-like portions 4, 5 may have an axially through hole 36, respectively. 37 which is centered with the center line CL1 and 37 respectively. CL2 and which is intended to allow part 4 and 4 respectively. 5 can be threaded onto a guide wire 43, which is intended to be arranged at, respectively. legs and which are intended to control the first resp. second screw-like part 4, 5 when it is to be screwed into the respective legs.

The illustrated wrist prosthesis may be arranged in a wrist 38. The legs of such and the legs of the arm and hand are shown schematically in Fig. 1 with dashed lines and these legs may be the arm's radius 39 (radius), one or more legs of the palm 40, for example the leg. 41 and an intermediate leg 42, e.g. metacarpal III, in the intermediary. As shown in the figure, the first screw-like part 4 has been screwed into the beam leg 39 and this part 4 has therefore been formed thicker but is shorter than the second screw-like part 5 and has larger first holes 10 than the first hole 11 of the second screw-like part 5. screw-like part 5 is screwed onto the wrist 38 shown at the head bone 41 and the intermediate leg 42.

Figures 8-12 show examples of how the first and second screw-like parts 4, 5 can be applied to the respective screws. legs 39, 41 and 42.

As shown in Figure 8, a guide wire 43, which is attached to a drilling machine 44, is drilled through the main leg 41 and into the intermediate leg 42. Thereafter, the drilling machine 44 is removed while the guide wire 43 is allowed to remain.

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As shown in Figure 9, then a tapered drill 45 and a tubular holder 46, through which the drill 45 is applied to a drill 47, are threaded onto the guide wire 43 and tapered holes are drilled into the main leg 41 and the intermediate leg 42.

As shown in Figure 10, the second screw-like part 5 is then threaded onto the guide wire 43. Next, the screwdriver 32 of the screwdriver 32, which is cannulated, i.e. has a longitudinal hole 31a, is threaded onto the guide wire 43 and into the second hole-like portion 5 of the second screw, after which the screwdriver 32 is rotated to screw the second screw-like part 5 into the holes in the main leg 41 and the intermediate leg 42. Then the screwdriver 32 and the guide wire 43 are removed.

As can be seen from Figures 11 and 12, a similar method is applied to affix the first screw-like portion 4 to the beam leg 39. Thus, it is apparent from Figure 11 that a guide wire 43 is attached to the beam leg 39, that a tapered drill 45 (as in this cases 45 are larger than the drill 45 shown in Figure 9) on the guide wire 43 and that with the drill 45 a tapered hole is drilled in the beam bone 39. In Figure 12 it is shown that by means of the screwdriver 32, the first screw-like part 4 is screwed onto the beam leg 39, after which the guide wire 43 is removed from it.

The first resp. other screw-like parts 4, 5 may consist of at least one material, while the hinge-bearing and hinge-bearing parts 6, 7 may consist of at least one other material. Thus, each first resp. other screw-like portions 4 and 5 have a core of metal material having an outer layer of a mat 528 545

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rial that is soluble when the first resp. other screw-like parts 4 and 5 are implanted.

Said core may conveniently consist of a titanium alloy while the soluble material may be or may contain calcium phosphate.

The hinge bearing and hinge bearing parts 6, 7 may consist of a chromium-cobalt alloy.

In addition to being simple and easy to apply the articulated joint described above, it allows the joint to be rotated. because the elbow bone can be left intact. In addition, the intervention can be made a little because you can only cut off smaller parts of the respective parts. ben 39; 41, 42 to secure the screw-like parts 4, 5. By using the joint prosthesis instead of an arthroplate plate, the joint can be made movable instead of rigid. If complications arise after the use of the joint prosthesis, this can be replaced by an arthroplasty plate as a secondary operation. It is also possible to screw in the screw-like parts 4, 5 in whole or only partially into the respective parts. ben 39; 41, 42.

The invention is not limited to the embodiment described above but may vary within the scope of the following claims. Thus, the prosthetic parts can be used for other joints other than wrists 38, e.g. for finger joints, thumb joints, elbow joints or large toe joints. The design of the prosthetic parts 2, 3 may also vary. Thus, the first holes 10, 11 in the screw-like portions 4, 5 may be partially conical or possibly have a different shape from the cone shape, and the hinge-bearing and hinge-bearing portions 6, 7 may of course be adapted thereto. The

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The press fit described may instead be another type of coupling device, the other holes 30, 33 may be of a different shape than that described and positioned in any other suitable manner than that described. The hinge bowl and hinge ball of the hinge bowl and hinge ball portions 6, 7 may be of a different shape than the shown edges and screw end portions 13, 15 of the screw-like parts 4, 5 may have rounded corners 13a, 13b. Finally, it can be mentioned that the screw tool 32 may be another suitable type of screw tool other than a screwdriver.

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