JP2520199Y2 - Puncture pin for fixation - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a percutaneous pin for osteosynthesis.

[0002]

BACKGROUND OF THE INVENTION Percutaneous pins have been known and used for many years in osteosynthesis surgery, especially extraosseous fusion. Such pins penetrate the fleshy and bony parts and are commonly used with extraosseous fixation devices of the type developed by Dr. Hoffmann. These extraosseous fixation devices include swivel joints, tie bars, sliding bars,
It consists of a locking clamp for holding and placing the joint and percutaneous pin. Hoffmann's extraosseous fixation device is an assembly framework that is placed around a portion or site of the human body and is arranged to externally hold a bone or fragment in place with the help of a group of pins or percutaneous pins. including.

There are many types of percutaneous pins on the market today. These pins generally include a threaded portion having a tapped portion at an end configured to form a thread when screwed into a boned portion or fragment. Before the pin is attached, the bone or bone fragment is first drilled with a required diameter approximately equal to or greater than the internal diameter of the screw. The end of the pin is then inserted into this drilled hole and the thread of the pin is screwed into this hole. During this operation, the tap provided at the end of the pin threads into the previously drilled hole. To screw the pin into the hollow hole, a chuck that engages a polygonal cross section, for example, a square cross section located at one end of the pin is widely used. In prior art pins, the ends of the threads can be shaped like the tips of drill bits or different shapes known to those skilled in the art.

There is also a type of pin known as a piercing pin, in which a rod having a drill tip at its free end is in front of the threaded portion. The puncture pin can be attached to the bone without pre-drilling a hole. In the case of a puncture pin,
The hole is drilled by the tip of the tip and the screw is set up by a tapping part provided at the beginning of the screw part.

Prior art transdermal pins are unable to provide very high quality perforations or taps. As with any drilling or tapping operation, the temperature rises in the working position, which can lead to necrosis and deterioration of bone tissue. Moreover, prior art pins do not provide a good tap surface. This surface is notched in some places, which makes it impossible to provide a good quality locking between the bone fragment and the pin when the pin is installed. Finally, prior art pins, due to their poor performance in drilling or tapping operations, can cause undue stress on bone when they are in place.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to overcome the above-mentioned drawbacks of the prior art, and is a screw for tapping work when the end of the screw portion penetrates a bone part or a fragment. In a percutaneous pin for fixation of a bone or bone fragment comprising a threaded portion with at least one groove at the front end of the part, at least one said groove forming a cutting edge of the tap each traversing said screw. The pin is provided with a clearance behind the cutting edge of the tap that approaches the centerline of the pin until it reaches a subsequent notch, the groove spiraling with respect to the axis of the screw. The invention provides a percutaneous pin characterized in that the spiral groove and the screw have the same thread direction.

[0007]

[Effects of the Invention] Since the groove is spiral, it is easy to insert the pin into the bone, and the thread direction of the groove spiral ("right-hand thread" or "left-hand thread") is the same as the thread direction of the thread part. As a result, it is better fixed to the bone.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The percutaneous pin 1 shown in FIGS. 1 and 3 comprises a screw part 2 which is the front part of the pin and a rear part 3 which is called the smooth part 3. The pin 1 is a cylindrical pin having a diameter smaller than its length, and a rear portion, that is, a smooth portion 3 is provided with a groove portion 4 and a terminal portion 5 having four faces. This end 5 allows the use of a chuck that allows the pin 1 to penetrate the bone or bone fragment, but not the groove 4
Acts to hold the chuck. The front part 2 of the pin 1 (see in particular FIG. 3) has a screw 6 in the form of a frusto-conical part 7 whose front part ends in a substantially flat surface 8 which is at right angles to the centerline of the pin. Including.

In FIGS. 3, 5 and 7, three grooves 9 are arranged 120 ° apart around the front end of the pin for tapping action. These grooves 9 take the form of two surfaces 10 and 11 forming two right angles, the surface 10 defining the cutting edge 12 of the tip at its free end (see also section in FIG. 7). ). Behind each of the cutting edges 12 is a clearance gap 13 which, in the direction of rotation of the pin, approaches the center line of the pin until it intersects the surface 11 of the subsequent groove 9.

The groove 9 is preferably formed by polishing. This polishing operation is performed by moving a circular grinding wheel in the tangential direction over the end portion of the screw 6. Polishing the groove 9 provides the cutting blade with a good surface finish and eliminates further finishing operations. The clearance 13 is similarly formed by feeding the grinding wheel to the end of the pin and rotating the pin to bring the grinding wheel closer to the center line of the pin.

The formation of grooves 9 and clearances by polishing gives very good results, but it will be apparent to a person skilled in the art that this work is possible by milling or any other suitable means.

Pins of the type shown in FIG. 3 are particularly used for implanting bone at a location where the tip of the pin does not risk damaging tissue near the bone at the end of the secondary cortex.

In other applications, however, it is desirable to mount a so-called puncture pin, that is, a pin such as the one shown in FIGS. 2 and 4, which continuously self-pierces and self-taps.

In FIG. 4, as in the previous description, this pin comprises a screw 6 terminating in a frustoconical portion 7. However, this pin differs in that the truncated conical section 7 is further forwardly provided with a cylindrical section 28 which ends in a substantially conical tip 29. This cylindrical portion 28 makes it possible to avoid interference between drilling and tapping operations in cortical bone of normal thickness, which is difficult to screw correctly into the bone. In the embodiment, this pin has two symmetrical grooves 30.

Alternatively, since the puncture pin as shown in FIG. 2 is received by the feed chuck as well as the screw part 2, the rear part 3 having the annular groove 4 in contact with the end, as in the pin of FIG. It is also possible to have an end 5 having four surfaces.

Threaded portion 2 includes a screw 6 having a forward conical portion 7 similar to that shown in detail in FIG. In this case as well, the dapping groove portion 9 can be formed using a circular grinding wheel that moves tangentially to the center line of the pin so as to start from the rod 16 in front of the truncated cone portion 7 and proceed to the screw portion 6. . This rod 16 is provided with a cutting tip 1 for drilling a hole which is shown in more detail in FIG.
It ends in front of 7. The point 17 at the end of the rod 16 of the puncture pin shown in FIG. 2 has the shape of a rounded top 22, which has two notches 23 in its upper part (FIG. 9). The tip 22 presenting this circular top is shown in FIG.
10 and has a particularly interesting structural feature showing a long parallelogram configuration including two cutting surfaces 24 each defining a cutting edge 25 followed by a flank 26 in the cross section of FIG. If the point is rotated in the direction of rotation indicated by arrow F, the surface 26 defines a sufficiently large clearance angle to allow removal of chips generated during the drilling of bone with the crest 22. You will find out. On the other hand, those skilled in the art will understand that the flat surface 24 in FIG.
It will be seen that it defines a cutting surface having Two elongated recesses 27 are provided adjacent to the cutting blade 25 in order to modify this cutting angle α to make it zero or some positive value. Therefore, the cutting angle α can be corrected and selected according to the preference of the user by changing the depth of the recess 27.

The rounded top shapes, their flanks 26 and their recesses 27 of FIGS. 9 and 10, which make the cutting angle zero or some positive value, have a very good quality compared to prior art piercing pins. Enables drilling work. Furthermore, the pointed tip is particularly suitable as it anchors itself in the bone and acts to drill a hole axially without lateral offset.

The pins just described in connection with FIGS. 1, 3 and 4 can vary in length from 75 to 200 mm and from 3 to 6 mm in diameter. The frusto-conical section typically has a tilt of 12 °.

The central threaded pin according to the embodiment of FIG. 2 has a total length of 175 to 350 mm and likewise has a diameter of 3 mm.
It may be in the range of 6 mm to 6 mm. The front portion of the pin, including the rod 16 shown in FIG. 2, has a diameter equal to or smaller than the inner diameter of the thread in the threaded portion 6. For 3, 4, 5 and 6 mm pins, section 16 can have diameters of 2, 3, 4 and 5 mm, respectively. In the case of the pin of FIG. 2, it is desirable to provide a frustoconical portion with a 6 ° tip.

Although in some of the embodiments described herein the thread is a single thread, it is possible to provide multiple threads instead so that the tap passes through the same tapping groove several times in succession. Of course it is possible.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of a transdermal pin.

FIG. 2 is a side view showing a second embodiment of a percutaneous pin, that is, a puncture pin.

FIG. 3 is an enlarged view showing the end of the pin designated III in FIG. 1 in a first embodiment of the pin, generally referred to as a half-point pin, inserted after the bone has been drilled to the appropriate diameter.

FIG. 4 is a view similar to FIG. 3, showing a second embodiment of a puncture pin, called a half-pin that self-pierces and self-taps, which acts to further drill before tapping.

FIG. 5 is an enlarged view showing the front end portion of the threaded portion of the puncture pin in the first embodiment.

FIG. 6 is a view similar to FIG. 5 in the second embodiment.

7 is a cross-sectional view taken along the line VII-VII of FIG.

8 is a cross-sectional view taken along the line VIII-VIII in FIG.

9 is an enlarged detail view showing the tip of the pin of FIG. 2 as indicated by arrow IX.

10 is a cross-sectional view of the tip in FIG. 9 taken along the line XX.

[Explanation of symbols]

1 ... percutaneous pin, 2 ... screw part, 3 ... smooth part,
4 ... groove part, 5 ... end part,
6 ... screw, 7 ... frustoconical portion, 8 ... flat surface,
9 ... Groove part, 10, 11 ... Surface, 12 ... Cutting blade, 13 ... Relief gap, 16 ... Rod,
17 ... Cutting tip, 22 ... Round top,
23 ... Notch, 24 ... Cutting surface, 25 ... Cutting blade, 26 ... Relief surface, 27 ... Elongated recess,
28 ... Cylindrical part, 29 ... Conical tip part,
30 ... Groove part.

Continuation of the front page (56) Reference JP-A-51-141953 (JP, A) JP-B-41-20009 (JP, B2) JP-B-52-49109 (JP, B1) US Pat. No. 4537185 (US, A)

Claims (13)

(57) [Scope of utility model registration request] 1. A bone or bone fragment comprising a threaded portion with at least one groove at the front end of the threaded portion for performing a tapping operation when the end of the threaded portion penetrates the bone or bone piece. Fixing percutaneous pin in the form of a notch in which each of the at least one groove portion forms a cutting edge of the tap traversing the screw, the pin being in a subsequent notch behind the cutting edge of the tap. A clearance gap is provided until reaching the center line of the pin, the groove portion is arranged spirally with respect to the axis of the screw, and the spiral groove portion and the screw are in the same thread direction. Characteristic transdermal pin. 2. The percutaneous pin according to claim 1, wherein the percutaneous pin includes at least two grooves that are regularly spaced around the pin. 3. The percutaneous pin according to claim 1, wherein the front portion of the screw portion is in the form of a frustoconical portion of the tip.
A percutaneous pin wherein the groove defines a cutting cone that extends over the forward conical portion of the threaded portion and the beginning of the central portion of the threaded portion. 4. The percutaneous pin according to claim 1, wherein the groove is in the form of a notch formed by two substantially perpendicular surfaces. 5. The percutaneous pin according to claim 1, wherein the groove portion is in the form of a notch having a substantially circular cross section. 6. The percutaneous pin according to claim 1, wherein the groove portion is formed by polishing after forming a screw having a conical portion at the tip thereof. 7. The percutaneous pin according to claim 3, wherein the front part of the frustoconical part ends in a plane perpendicular to the axis of the pin and is pre-drilled in the bone part. A percutaneous pin characterized by being intended to fit in a hole. 8. The percutaneous pin according to claim 3, wherein a rod having a diameter equal to or smaller than an inner thread diameter of the threaded portion is present in front of the front conical portion of the screw,
A percutaneous pin characterized in that the rod ends in a flat drill end having the shape of a rounded top. 9. A percutaneous pin according to claim 8, characterized in that said flat rounded end has two notches which are located opposite one another in the upper part. Transdermal pin. 10. The percutaneous pin of claim 8, wherein said flat, rounded top end has a long parallelogram-shaped cross section defining two opposing cutting surfaces. There is a surface forming a clearance angle behind the cutting surface, the cutting surface and the clearance surface together form one cutting edge, and the cutting surface is an elongated spoon shape located adjacent to the cutting edge. A percutaneous pin, characterized by having a concave portion and correcting the cutting angle to be zero or a positive value. 11. The percutaneous pin according to claim 3, wherein a forward portion of the frustoconical portion is at least indirectly forward of a conical portion including the groove to form a drill end. A percutaneous pin characterized by: 12. The percutaneous pin according to claim 11, wherein
A percutaneous pin, characterized in that, in front of the conical part of the drill, there is a substantially cylindrical part arranged between the frustoconical part of the tip and the conical part of the drill. 13. The percutaneous pin according to claim 12,
The percutaneous pin, wherein the diameter of the cylindrical drill portion is larger than the inner diameter of the threaded portion.