FR3047891A1 - PROTECTIVE CAP WITH MEASUREMENTS OF A OSTEOSYNTHESIS PIN WITH BODY FOR FASTENING IT - Google Patents

Abstract

The invention relates to an assembly comprising a protective cap of an osteosynthesis pin and a pin, said cap having at least one flat. The invention also relates to this cap and the assembly with a fastener, as well as the method of introduction of the flattened cap.

Description

PROTECTIVE CAP WITH MEASUREMENTS OF A OSTEOSYNTHESIS PIN WITH BODY FOR FASTENING IT

FIELD OF THE INVENTION

The present invention relates to a protective cap flats of an osteosynthesis pin and an assembly comprising this cap and a fastener of the cap on the spindle.

TECHNICAL BACKGROUND

It is known that the pins used in osteoarticular pathology, in particular to keep two parts of a fractured bone aligned, are introduced for this purpose into the bone tissue on either side of the fracture. These should not migrate during the reduction of the fracture. Indeed protruding out of the bone tissue of the unprotected spindle can cause tendon rupture, lesions of neurovascular elements, lesions of the skin, vectors of secondary infection, and also make it difficult to extract further this brooch.

EP-A-0 323 429 discloses a locking screw of an osteosynthesis plate for the treatment of fractures. This screw comprises a threaded portion, a head and a gripping rod secured to the head via an embrittlement zone formed by a constriction making the rod separable from the head under the effect of a predetermined torque of torsion , at the end of screwing.

FR-A-2,633,822 discloses an assembly comprising a cap and a fastener of the cap on a pin, the cap having a housing adapted to receive one end of the pin and a tapped hole opening transversely in this housing, adapted to receive a fixing screw for securing the spindle and spherical pin protective tip.

EP-A-0 543 709 discloses an assembly comprising a cap and a fixing member of the cap on a pin, the cap having a housing adapted to receive one end of the pin and a tapped hole opening transversely in this housing, the handle of the fastener having a fragile zone in its end portion allowing its rupture at the end of screwing and the blocking of the cap.

In the latter document, the extraction of the spindle can be difficult because the clamp used is likely to rip on the cap, potentially damaging the surrounding tissue.

There is therefore a real need for a protective spindle tip that allows a simple and effective extraction of the latter without risk of sliding of the clamp. The invention therefore aims to propose a satisfactory solution to the problem above.

SUMMARY OF THE INVENTION The invention relates in the first place to ...

By cap is meant a spindle protective tip that protects the cut portion of the spindle and whose attachment to it is provided by a micro-screwing system. Its role is to protect the sharp end of the spindle, to avoid the migration of the spindle and to allow compression. In the invention the cap allows easy extraction of the spindle. The subject of the invention is an assembly comprising a cap for protecting an osteosynthesis pin, and a fastener for securing the cap on the pin, via an end portion of said fixing member, the cap comprising a housing adapted to receive one end of the spindle, and a tapped hole opening transversely in this housing, adapted to receive a fixing screw extending the end portion and for securing the pin and the cap, the screw having, at its junction with the end of said end portion, a fragile zone that allows its rupture at the end of screwing and its locking in the transverse hole, wherein said cap comprises at least one flat. The invention also relates to a sterile protection cap of an osteosynthesis pin, comprising a housing adapted to receive one end of the spindle, and a tapped hole opening transversely in this housing, adapted to receive a fixing screw extending the end portion and for securing the pin and the cap, wherein said cap comprises at least one flat. The invention also relates to an assembly comprising a cap for protecting an osteosynthesis pin and an osteosynthesis pin, the cap comprising a housing receiving an end of the pin, and a tapped hole opening transversely in this housing, receiving a fixing screw locked in the transverse hole, said cap being fixed with the osteosynthesis pin, said cap comprising at least one flat. The subject of the invention is also a method for producing the protective cap and osteosynthesis pin assembly according to the invention, comprising the following steps: a protective cap and fastener assembly according to the invention is provided; the end cap of the spindle is approached through the housing until the tip of the spindle comes to rest on the bottom of this housing, - the screw is screwed by rotating the tool like a screwdriver and force to break the fragile area, and attach the cap to the spindle.

According to one embodiment, the length of the osteosynthesis pin is adjusted by cutting. The subject of the invention is also a method for extracting the protective cap and osteosynthesis pin assembly according to the invention, comprising the step of gripping the cap at the level of the flats using a pair of forceps, and the application of an extraction force.

According to one embodiment, the cap has two flats parallel to each other.

According to a variant, said at least one flat is parallel to the tapped hole; according to another variant, it is perpendicular to the tapped hole.

According to a variant, said at least one flat extends over the entire height of the cap; in another variant said at least one flat extends over a portion of the height of the cap and from a shoulder at the base of the cap.

According to one embodiment, the fastener of the cap on the spindle is provided with a terminal portion made one-piece with the screw, a weakened fracture zone at the end of screwing being formed between the screw and said end portion. For example, the weakened zone is a narrowing of the end portion, forming a neck at the junction with the screw.

According to one embodiment, the fixing member is a handle, preferably coated with asperities, for example a knurling.

According to one embodiment, the fragile zone is located under the surface of the cap.

According to one embodiment, the cap has a bore for receiving a strapping wire of a bone. One can also provide that the cap is perforated by a bore to slide the cap on the spindle and / or the passage of a strapping wire (including a bone that can also receive a pin, with or without the cap according to the invention.

According to one embodiment, the assemblies according to the invention and the cap according to the invention are sterile.

The present invention overcomes the disadvantages of the state of the art. It provides more particularly an assembly formed by a flattened cap and a fixing member thereof on the spindle. Such a flats cap forms at the end of the spindle a prominence which effectively opposes any unwanted movement of this spindle. The cap has flats allowing a stable and strong grip of the pin during extraction without risk of sliding of the clamp. The clamp no longer slipping there is more risk of damaging the tissue around the cap. It is also possible to use a rack-and-pinion clamp which offers additional comfort for the practitioner.

The locking screw of the flattened cap on the spindle is initially part of its installation tool, which it does not dissociate at the end of screwing, by breaking the weakened zone. This arrangement avoids the use of a screwdriver, which would be particularly difficult in the conditions of the surgical procedure and given the small dimensions of the screw and the flattened cap.

Other features and advantages of the invention will become apparent from the description which follows, with reference to the accompanying drawings which illustrate several embodiments as non-limiting examples. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 represents a half-elevation view half-lengthwise on an enlarged scale of a first embodiment of the assembly targeted by the invention, comprising a flatscap and a fastener of the flatscap on the spindle; .

FIG. 2 shows a mid-sectional mid-elevation view of an embodiment of the enlarged flatscap cap, as well as its fixing screw on the spindle and the end portion of the support member of the screw.

FIG. 3 is an elevational view of the flattened cap in the direction of arrow F in FIG.

Figure 4a shows a cross-sectional view along AA of Fig.5 of an embodiment of the flats cap according to the invention.

Fig. 4b is a cross-sectional view of a second embodiment of the flattened cap according to the invention.

Figure 5 shows a side view of the cap of Fig.4a.

Figure 6 shows a sectional view according to a third embodiment of the invention.

Figure 7 shows a perspective view of the flattened cap according to the invention.

Figure 8 shows a radiographic view of an application of the invention to the surgical treatment of scaphoid fracture or scaphoid pseudarthrosis.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION The invention is now described in more detail and in a nonlimiting manner in the description which follows.

The present invention overcomes the disadvantages of the state of the art. It more particularly provides the device represented in FIG. 1 which comprises a cap 1 for protecting an osteosynthesis pin such as 2, a member 3 for attaching the cap 1 to the pin, this member being provided with an end portion 4 for supporting the cap 1, and finally a protective cap 5 covering the end portion 4 and the cap 1. The cap 5, made for example of any suitable plastic material, has a tubular shape and can be friction-fitted on a cylindrical base 6 coaxial with the end part 4. This base 6 is extended by a handle 7 of manual handling, the surface of which is preferably coated with asperities, for example a knurling 8.

The cap 1, shown in detail in FIGS. 2 and 3, comprises a housing 9 formed by a blind hole adapted to receive one end of the pin 2. The cap 1 comprises at least two flats (100, 101). It can also be perforated at its top, for example by a bore.

In the implant cap 1, is furthermore provided a tapped hole 11 opening transversely into the housing 9, and adapted to receive a screw 12 for securing the pin 2 and the cap 1. The flats (100, 101) of the cap 1 are located parallel or perpendicular to the tapped hole 11, as will be described in more detail with reference to Figures 4a and 4b. In the embodiment shown, the hole 11 passes right through the cap 1, perpendicular to the axis of the cylindrical housing 9, only its portion for receiving the screw 12 being threaded. It is possible to have only the threaded portion without a hole passing through the entire cap.

The height of the cap corresponds to the size of the cap from its base to its top. This height is between 2 mm and 6 mm, preferably between 3 mm and 5 mm. The diameter of the cap excluding flats is between 3 mm and 8 mm, preferably between 3 mm and 6 mm.

The cap may be made of any material suitable for implantation, for example polymer (eg PEEK), and preferably metal, especially stainless steel, such as 316L or titanium Ta6v4.

The screw 12 has a head 12a adapted to fit the cylindrical surface of the pin 2 and crash when necessary. It is made one-piece with the end portion 4 of the handle-screw 3, and has, at its junction with the end of this portion 4, a fragile zone (or embrittled, these two terms being used interchangeably) 13 allowing its break in the end screwing and thus the separation of the screw 12 relative to the neck forming the end portion 4.

The establishment of the flats cap 1 and its fixing to the spindle 2 are carried out very simply, in the following manner.

After having taken out the flattened cap 1 of the cover 5, the surgeon, holding the handle 7 in his hand, approaches the cap 1 of the end of the pin 2 which he introduces into the housing 9, until his tip come to a stop on the bottom of this dwelling. The length of the pin was possibly previously adapted by the surgeon, in particular by cutting it. Then, the screw 12 is only partially embedded in its hole 11, the surgeon begins to screw it by rotating the tool 3 as a screwdriver. At the end of screwing, the head 12a of the screw 12 is tightly applied against the pin 2 that it locks in translation and possibly also in rotation relative to the cap 1. Then, by forcing on the handle 7, the surgeon causes the breaking of the fragile zone 13, located at this moment inside the tapped hole 11. The screw 12 is then in place and fixes the cap 1 to the pin 2.

According to the second embodiment of the flats cap 1, shown in Fig.4 (a, b) the hole 11 passes right through the cap 1, perpendicular to the axis of the cylindrical housing 9. The two flats (100, 101) may be located perpendicular to the tap (Fig. 4a) or parallel to the tap (Fig. 4b).

Figure 5 is a sectional view of the embodiment of Figure 4a. It can be provided that the cap incorporates an embodiment with a bore. The body of the flattened cap is larger and may be perforated by a bore, preferably oriented perpendicularly to the axis of the housing 9 and thus to the pin 2. The bore may pass right through the flattened cap 1, and allows the passage of a strapping wire or a bone stay. This stay is useful in the embodiments described in FIGS. 6, 7, 10 and 14 of EP-A-0 543 709. The use of metallic or textile threads constituting guying is of interest in a certain number of applications: fracture patella, olecranon fracture etc. The proximal ends of the pins protected by the caps allow the establishment of a stay. The invention therefore also relates to the embodiment of the guying and is expressly referred to the aforementioned EP-A-0 543 709 and the corresponding embodiments.

Of course, for a given dimension of the flatscap (1), the cavity 9 receiving the spindle 2 may have a variable diameter, adapted to that of the spindle, which may also be unthreaded, or partially or fully threaded.

The flats (100, 101) may extend over all or part of the height of the cap. In a version shown in Figure 6, the flats (100,101) are in extension of shoulders (102,103). These shoulders can serve as a stop for the grippers, thus further limiting the inadvertent movements of the gripper and thus increasing safety during the extraction of the pins.

An exemplary implementation of the invention will now be described with reference to FIG.

FIG. 8 shows a fractured carpal scaphoid 31, provided with two pins 23 whose ends outside the scaphoid are capped with a flatscap 1. Such a device is applicable to the surgical treatment of carpal scaphoid pseudarthoses, by associating or not a bone graft, other ossicles of carp or tarsus, tarsus in fractures-dislocations involving tarsus and metatarsal, or any other fracture pathology of tarsus and metatarsal. Other implementations correspond to the embodiments of FIGS. 6 to 17 of EP-A-0 543 709, to which it is expressly referred as well as to the corresponding description.

The flattened cap 1 protects the surrounding tissues, opposing any inadvertent movement of the spindle or migration.

The flat protective cap, placed under the skin, can be easily identified manually by palpation, which facilitates the extraction of the pin by the surgeon. In this way, the stress of having to use an image intensifier is eliminated for the latter, which saves time and prevents radiation emitted by the image intensifier.

Correlatively, the extraction of the pins after consolidation of the fracture does not cause significant injury by the unwanted search of the pins, and thus makes less invasive surgery. Ablation of the pins provided with a flat protective cap according to the invention is thus made relatively easy remote from the establishment (that is to say after a certain time). The implant consisting of the flat protective cap according to the invention allows the surgeon to choose a pin of the desired length. Simply put the spindle in place, cut it to the desired length and attach the flat protective cap. This presents a considerable advantage over prior art predetermined size auto-breakable pins. These pins, protected by a tip, are usually available 0.5cm in 0.5cm. They also expose the disadvantage of a break downstream protective olive, thus losing all the advantages of a protective tip of the spit. In addition, the predetermination of the lengths may require that the pointed end of the pin be passed through the opposite cortex, which is a source of irritation to the surrounding tissue. The protective implant with flats according to the invention can create, within a fracture or arthrodesis focus, a certain degree of compression, by the use of threaded pins at their distal ends, the flattened cap. being placed in the proximal position.

The protective cap 1 according to the invention is very easy to use and can adapt to totally, partially or non-threaded pins.

The protective cap 1 according to the invention has the advantage of not rolling on the surgical instrument table thanks to the presence of the flats (100, 101).

According to one embodiment, it is possible to proceed with a family of caps that adapts to the different diameters of the pins. However, even with variable diameters, it will be possible to have a length of tapping of the flats cap 1 always identical. This has the advantage that the same force is always necessary to cause the rupture and cut the screw 12; the surgeon will have the same gesture regardless of the pin to implement.

Claims (29)

1. Assembly comprising a cap (1) for protecting an osteosynthesis pin (2), and a member (3) for fixing the cap on the pin, via an end portion (4) of said organ fixing, the cap having a housing (9) adapted to receive one end of the spindle, and a threaded hole (11) opening transversely in this housing, adapted to receive a fastening screw (12) extending the end portion (4). and for securing the pin and the cap, the screw (12) having, at its junction with the end of said end portion, a fragile zone (13) which allows its rupture at the end of screwing and its locking in the transverse hole (11), wherein said cap comprises at least one flat (100, 101). 2. The assembly of claim 1, wherein the cap (1) has two flats parallel to each other. 3. The assembly of claim 1 or 2, wherein said at least one flat (100, 101) is parallel to the tapped hole (11). 4. The assembly of claim 1 or 2, wherein said at least one flat (100, 101) is perpendicular to the tapped hole (11). 5. An assembly according to one of claims 1 to 4, wherein said at least one flat (100, 101) extends over the entire height of the cap. 6. An assembly according to one of claims 1 to 4, wherein said at least one flat (100, 101) extends over a portion of the height of the cap and from a shoulder (102, 103) to the base of the cap (1). 7. Assembly according to one of the preceding claims wherein the member (3) for fixing the cap on the spindle (2) is provided with an end portion (4) made one-piece with the screw (12), a weakened zone (13) breaking at the end of screwing being formed between the screw and said end portion. 8. Assembly according to one of the preceding claims, wherein the weakened zone (13) is a narrowing of the end portion (4) forming a neck at the junction with the screw (12). 9. Assembly according to one of the preceding claims, wherein the fixing member (3) is a handle, preferably coated with asperities (8), for example a knurling. 10. Assembly according to one of the preceding claims, wherein the fragile zone (13) is located under the surface of the cap (1) · 11. Assembly according to one of the preceding claims, wherein the cap (1) comprises a bore for receiving a strapping wire of a bone. 12. Assembly according to one of the preceding claims, which is sterile. 13. Sterile cap (1) for protecting an osteosynthesis pin (2), comprising a housing (9) adapted to receive one end of the spindle, and a tapped hole (11) opening transversely in this housing, adapted for receiving a fixing screw (12) extending the end portion (4) and for securing the pin and the cap, wherein said cap comprises at least one flat (100,101 '). 14. Cap (1) according to claim 13, comprising two flats (100, 101) parallel to each other. 15. Cap (1) according to claim 13 or 14, wherein said at least one flat (100,101) is parallel to the threaded hole (11). 16. Cap (1) according to claim 13 or 14, wherein said at least one flat (100, 101) is perpendicular to the threaded hole (11). 17. Cap according to one of claims 13 to 16, wherein said at least one flat (100, 101) extends over the entire height of the cap. 18. Cap according to one of claims 13 to 16, wherein said at least one flat (100, 101) extends over a portion of the height of the cap and from a shoulder (102, 103) at the base of said cap (1). 19. Cap according to one of claims 13 to 18, comprising a bore for receiving a strapping wire of a bone. 20. An assembly comprising a cap (1) for protecting an osteosynthesis pin (2) and an osteosynthesis pin (2), the cap (1) comprising a housing (9) receiving one end of the pin, and a tapped hole (11) opening transversely in this housing, receiving a fixing screw (12) locked in the transverse hole (11), said cap (1) being fixed with the pin (2) of osteosynthesis, said cap ( 1) having at least one flat (100, 101). 21. The assembly of claim 20, wherein the cap (1) has two flats parallel to each other. 22. The assembly of claim 20 or 21, wherein said at least one flat (100, 101) is parallel to the tapped hole (11). 23. The assembly of claim 20 or 21, wherein said at least one flat (100, 101) is perpendicular to the tapped hole (11). 24. An assembly according to one of claims 20 to 23, wherein said at least one flat (100, 101) extends over the entire height of the cap. 25. An assembly according to one of claims 20 to 23, wherein said at least one flat (100, 101) extends over part of the height of the cap and from a shoulder (102, 103) at the base of the cap (1). 26. An assembly according to one of claims 20 to 25, wherein the cap (1) has a bore for receiving a strapping wire of a bone. 27. A method of producing the assembly according to one of claims 20 to 26, comprising the following steps: - is provided an assembly according to one of claims 1 to 11 - the end cap (1) is approaching the end from the spindle (2) thanks to the housing (9) until the point of the spindle (2) comes into abutment on the bottom of this housing (9), - the screw (12) is screwed by rotating the spindle (9). tool (3) as a screwdriver and in force to break the fragile area (13), and fix the cap (1) to the spindle (2). 28. Method according to the preceding claim wherein the length of the pin (2) osteosynthesis is adjusted by cutting. 29. A method of extracting the assembly according to one of claims 20 to 26, comprising the step of gripping the cap (1) at the flats (100, 101) using a clamp, and the application of an extraction force.