DE19542351A1 - Closure device for closing off opening to medulla - Google Patents

Abstract

The closure device (1) for closing off the opening to the medulla has a central hollow area (5) which has a valve mechanism connected to it. By means of the valve mechanism, the hollow area can be filled by a fluid under pressure. The valve also prevents the fluid from flowing back. The valve mechanism consists of a bulbous body (6) which projects into the hollow area of the medulla closure device. An infusion needle (2) is pushed through the body into the hollow area to fill it with fluid under pressure.

Description

In the cemented endoprosthetics of long bones, the distal seal of the Medullary canal of great importance (Soballe K, Christensen F (1988) Improved Cementation in total hip replacement. Arch Orthop Trauma Surg 107: 50-53). It should thus preventing the bone cement from going deeper than required Tubular bone is inserted. For the purpose of sealing the medullary canal of a tubular bone so-called medullary space stoppers are used, whereby both absorbable and non-absorbable materials are used (P 28 14 037.6-35, P 28 50 586.4-35, P 30 15 669.5-35).

A major problem with the sealing of the medullary canal is the individual Variation of its diameter. For this reason, the marrow stoppers are in Different sizes offered, or elastic, so that an intraoperative one better adaptation to the geometry of the bone is possible. Especially in the Patent P 28 14 037.6-35 refers to this problem. A good Adaptation to the diameter of the bony recess is particularly important important to the marrow stoppers, which are made of a solid material, such as. B. Methyl methacrylate are made. But also marrow stoppers, which have a certain Have flexibility, e.g. B. marrow stopper made of a fleece or soft Polyethylene are made, differences in medullary canal diameter only compensate within certain limits, because when filling the bone cement and when inserting the prosthesis relatively high pressures up to 4 bar (impact G, Dingeldein E, Weiss G, Regele H, Sommoggy v. St (1976). Are intraoperative Circulatory complications in alloarthroplasty of the hip joint due to methyl methacrylate conditionally? Anesthesiologist 25: 60-67) arise, one that is too loose-fitting Would push the marrow stopper out of its position.

These problems are solved in the present invention in that the Marrow stopper

• 1. is built from a soft material,
• 2. has a central cavity  and
• 3. a fluid is introduced under pressure into this cavity and held there, so that the marrow stopper expands accordingly and is pressed against the wall of the bony medullary cavity and so seals.

By inflating the central hollow body, a particularly good pressing is achieved of the marrow stopper reached on the bone wall. Will - as in DE 42 19 564 A1 proposed as part of a membrane seal - only the edge of the The medullary space stopper is inflatable, so it is pressed onto the bone Extremely small area and the sealing of the bone cavity that can be achieved with it worse.

Naturally, an elastic material must be chosen as the material that can expand according to the inflation pressure. As an example non-absorbable material would come e.g. B. soft polyethylene in question. Especially However, it is advantageous if a material is selected that resorbs in the body (e.g. degrades hydrolytically or enzymatically). As an example of a well suited one Material from this class should be mixed with water and glycerol Gelatin, which due to the blended glycerol has an elastic consistency Persists. Different recipes for preparing gelatin can be found in: Voigt R, Werchan Dora (1981) On the melting behavior of gelatin gels. Pharmacy 36: 624-628.

As the fluid introduced into the medullary stopper under pressure is, for. Legs sterile isotonic saline or simply air or gas. This fluid is allowed out do not escape the marrow stopper. This requires a valve mechanism which retains the fluid in the cavity of the medullary canal. It is it makes sense that the medullary space stopper over the guide rod, which is used to place the Stoppers is required is filled.

It is conceivable that the medullary space stopper ( 1 ) is punctured with the aid of a needle ( 2 ) which is firmly connected to the perforated guide rod ( 3 ). On the one hand, this needle creates a temporary connection between the stopper and the guide rod (this connection can be further improved by the end plate ( 4 ) of the guide rod or by inserting the guide rod into the medullary space stopper), and on the other hand the cavity ( 5 ) of the stopper filled by the needle by z. B. with a syringe at the other end of the guide rod, a fluid is pressed through the pierced guide rod and so through the needle into the cavity of the medullary canal. If the material is very soft and the filling pressure is not too great, the puncture hole closes automatically after the needle is withdrawn, so that no substantial amount of fluid can escape from the stopper through the puncture hole. However, this closure is not sufficient for a harder material of the medullary canal and higher filling pressures. In order to achieve a secure seal here, a bulge ( 6 ) can be attached to the interior of the medullary space stop at the puncture site. This bulge is pressed together by the pressure built up in the cavity ( 5 ), so that the puncture channel of the puncture needle is pressed together. Since the pressure with which the puncture channel is compressed increases with the filling pressure of the medullary space stopper, a reliable sealing of the puncture site can be achieved even at high filling pressures.

It is also possible to dispense with the puncture needle on the guide rod. For this purpose, the pierced guide rod z. B. in a conical bore ( 10 ) with the marrow stopper ( 12 ) made of a soft material can be temporarily connected by positive locking and through a hole ( 11 ) in the marrow stopper, a fluid can be pressed into the cavity ( 13 ) by the guide rod. A valve mechanism prevents the fluid from escaping from the stopper, the nose protruding into the stopper again being able to serve as the valve, which is compressed by the internal pressure of the stopper and thus compresses and seals the thin hole ( 9 ).

Of course, all other known valve mechanisms are also conceivable Prevent the fluid from flowing back out of the medullary plug.

In the following, the invention is to be further explained by the figures. It shows:

Fig. 1 shows a cut marrow stopper ( 1 ) in oblique supervision. The guide rod ( 3 ) is fixed to the puncture needle ( 2 ) and the end plate ( 4 ) and temporarily connected to the medullary space stopper ( 1 ) by the puncture needle and the seat of the medullary space stopper on the end plate. The puncture needle must be pierced through the nose ( 6 ), which protrudes into the cavity ( 5 ) so that when the needle is pulled out, the internal pressure compresses the nose and closes the puncture hole.

Fig. 2 shows a cut marrow stopper ( 8 ) in oblique supervision. The guide rod ( 7 ) is fixed to the puncture needle ( 9 ) and temporarily connected to the medullary space stopper ( 8 ) through the puncture needle and by pushing the guide rod into the recess in the medullary space stopper.

Fig. 3 shows a cut open marrow stopper ( 12 ) in oblique supervision. The management staff has an undercut - e.g. B. a protruding into the medullary cone ( 10 ) - temporarily connected by positive locking to the medullary can and can be pulled out of the undercut after filling the medullary canal with a fluid. The ventilation hole ( 11 ), which projects through the nose ( 14 ) into the cavity ( 13 ), is closed by the internal pressure acting on the nose ( 11 ) in the sense of a valve.

Fig. 4 a marrow stopper ( 15 ) in oblique supervision. For better insertion into the bone cavity, the side that is first pushed into the bone recess is rounded ( 16 ). The surface of the stopper can be structured - e.g. B. with knobs ( 17 ) - are executed.

As an example of a highly suitable absorbable material, the one in Example 1 described mixture apply, which is composed as follows

example 1

6 parts glycerol
4 parts of water.

This liquid in the weight ratio Flssk./Gel. = 2.5 with Mix pork gelatin (300 bloom). After swelling and heating this mass is injection moldable and after cooling and hardening of suitable soft consistency.

Of course, there are other mixing ratios with other types of gelatin and Of course, other resorbable materials are also conceivable that are similarly elastic Have material properties.

Claims (3)

1. marrow stopper for sealing bone openings, characterized in that the marrow stopper has a central cavity and a valve mechanism connected therewith, via which the cavity of the stopper can be filled with a fluid under pressure and which prevents the fluid after filling flows out again. 2. medullary space stopper for sealing bone openings according to claim 1, characterized in that the valve mechanism consists of a protrusion that the in the cavity The medullary canal protrudes and is pushed through the puncture needle through which the medullary space stopper can be filled with a fluid, so that the resulting internal pressure in the cavity of the Markraumstoppers this bulge is pressed together, so that Puncture hole compressed even after pulling back the puncture needle and so closed. 3. medullary space stopper for sealing bone openings according to claim 1, characterized in that the valve mechanism consists of a protrusion that protrudes into the cavity of the The medullary canal protrudes and the one small in diameter Has connection to the outside, so that the marrow stopper with a fluid can be filled through this connection, so that through the so resulting internal pressure in the cavity of the medullary canopy Bulge is pressed together, so that the connection after pressed together on the outside and so the cavity of the medullary canal is closed.