Connector For Fractured Tubular Bones

Abstract

An elongated rod-shaped element can be inserted into the curved longitudinal cavity of a fractured tubular bone. At its front end it is provided with an expander portion by means of which it can expand an expansion element provided at the front end of a tubular sleeve which surrounds the rod, when the latter is moved axially and rearwardly with respect to the front end of the tubular sleeve. The expander portion may be releasably connected with the rod for which purpose inter-engaging coupling portions may be provided on the rod and on the expander portion.

Description

BACKGROUND OF THE INVENTION

The present invention relates generally to a medical appliance and more particularly to a connector for fractured tubular bones.

Connectors for fractured bones are known, and it is known to use connectors having expansible elements for anchoring in a hole which is drilled into the bone fragments which are to be reunited. If, however, tubular bones are fractured -- which have a longitudinally extending curved interior cavity which is filled with bone marrow -- it was until recently unknown to use that type of connector; instead these bone fractures were always repaired by driving pins into the fragments of the bone.

The state of the art was advanced in this respect with our proposal in a co-pending application Ser. No. 227,371 filed in our names on Feb. 18, 1972, under the title "Supporting Device for Fractured Tubular Bones," wherein there is proposed a sleeve-shaped support element into which a rod-shaped expander element is inserted. The support element is curved in a manner which is at least substantially the same as the curvature of the interior cavity of the tubular bone, and when inserted into this cavity via an opening drilled into the bone for this purpose in order to afford access to the cavity, the support element is in contact with the wall surface bounding the bone marrow cavity over a relatively large surface area, due to its curvature corresponding to that of the cavity itself. With this device the fragment of the bone are secured against lateral displacement and cannot shift relative to one another at the fracture line. Because of this, callus may be formed in a very brief time at the fracture line, thus reuniting the bone fragments.

The device in the aforementioned copending application can be anchored by means of an expansible portion in the bone fragments, permitting a much earlier application of loads to the bone than was possible with the previous practice of driving pins into the bones. Furthermore, the fact that the support element can be so anchored serves, of course, to eliminate the need for the use of wires or pins which might otherwise have to be driven into the bone from the side in order to secure the support element against shifting or twisting in the cavity, and the overall effect observed with the construction set forth in the above-mentioned application is a significant reduction in the hospitalization time of a patient whose fracture has been repaired with the aforementioned device.

However, it has also been observed that even this significantly improved device does not meet all requirements as yet. The support device according to the aforementioned application can be readily inserted into the cavity of the tubular bone when the bone fragments are either not or only slightly displaced relative to one another in lateral direction at the fracture line. However, if such displacement has occurred and is of a more than slight nature, then the fact that the outer diameter of the sleeve-shaped support element is adapted to the inside diameter of the bone marrow cavity wouls result, when the device is driven into the cavity in contact with the laterally displaced downstream bone fragment, that is the fragment which the device would encounter only after it has been driven into the first fragment, in desctruction of this downstream bone fragment beyond the fracture line.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of the present invention to provide a device or connector of the type here under discussion which is a further improvement over what is known from the aforementioned application and which avoids the disadvantages just outlined.

More particularly it is an object of the present invention to provide an improved supporting device for fractured tubular bones having a longitudinally extending interior cavity.

An additional object of the present invention is to provide such a device which permits preliminary fixation of the bone fragments in their correct relative position before the supporting sleeve of the device is inserted into the bone marrow cavity, and which permits holding them in this position until the supporting sleeve has been so inserted.

In pursuance of these objects and of others which will become apparent hereafter, one feature of the invention resides, briefly stated, in a supporting device for fractured tubular bones having a longitudinally extending interior cavity which device comprises an elongated rod-shaped element adapted to be inserted with clearance into the cavity and having a trailing end portion and a leading end portion. An expander element is provided on the leading end portion and an elongated supporting tube is provided, being dimensioned to fit over the rod-shaped slement and adapted to be inserted into the cavity by sliding over the rear end portion and onto the rod-shaped element. An expansible element is provided at the front end of the tube and is dimensioned to abut the expander element when the tube is slid over the rod-shaped element. Moving means is also provided for the purpose of moving the rod-shaped element in the tube axially of the same and rearwardly away from the front end of the tube whereby the expander element is drawn into and thereby expands the expansible element.

Another concept according to the present invention proposes to achieve the aforementioned objects by utilizing a supporting device having an elongated curved supporting tube element adapted for insertion into the cavity longitudinally thereof and having a leading end portion. An expansible element is provided on the leading end portion and an expander element is also provided for expanding the expansible element. A rod-shaped element is receivable in the tube element and has a front portion, a rear portion and an intermediate portion of which at least the latter has a cross-section so dimensioned as to permit angular displacement of the rod-shaped element in the tube element. Cooperating coupling portions are provided on the expander element and the front portion of the rod-shaped element in order to effect coupling of the expander element to the rod-shaped element in response to angular displacement of the latter. Moving means is again provided which moves the rod-shaped element in the tube rearwardly of the leading end portion so as to effect expansion of the expansion element with the expander element when the latter is connected with the rod-shaped element.

When the device is constructed in accordance with the first-mentioned concept of the invention, the rod-shaped element in fact serves as a pin permitting the preliminary fixation of the bone fragments relative to one another. The fractured tubular bone is first provided with a hole in the region of its bulge, so as to gain access to the bone marrow cavity. Through this hole, provided in conventional manner with a drill or the like, is inserted the rod-shaped element -- which is curved in conformance with the curvature of the bone marrow cavity. The outside diameter of the rod-shaped element, which is small with respect to the diameter of the bone marrow cavity, makes it possible to insert the rod into all of the bone fragments without any difficulty, even though a relatively significant lateral displacement of the bone fragments relative to one another at the fracture line may have occurred.

Once the rod-shaped element is so inserted into the bone marrow cavity, the fragments are now aligned in longitudinal direction and held in this position. Over the thus inserted rod the similarly curved supporting tube is then pushed into the bone marrow cavity untl the expansible element which is provided at the front end of the tube, comes in contact with the expander element which is provided at the front end of the rod-shaped element. The moving means is now operated, consisting advantageously of a cap sleeve which is internally threaded to mesh with external thread provided at the rear end of the rod-shaped element, and when this is done the rod-shaped element is drawn axially rearwardly into the tube so that the expander element expands the expansible element on the tube, anchoring the entire device in one of the bone fragments.

During the anchoring operation the rod-shaped element moves only in axial direction of the tube, it being evident that the curvature of the tube and of the rod-shaped element will prevent a turning or twisting of the latter in the tube. Due to the curvature of the tube, the latter is in contact with the inner wall bounding the bone marrow cavity over a relatively large surface area, whereby an excellent securing of the bone fragments against lateral displacement is obtained. Of course, the anchoring of the device in the bone fragment means that the other bone fragment in which the device is not anchored may be engaged by the moving means or another component provided for this purpose, thereby exerting an axial stress upon the bone fragments in a sense drawing them together to prevent their relative axial displacement.

It is advantageous, but not absolutely necessary to provide mating screw threads on the rod-shaped element and on the expander element, so that the latter can be releasably connected with the rod-shaped element; the same expedient may be used for releasably connecting the expansible element to the supporting tube.

As is well known in this field of art, components for devices of the type under discussion are usually manufactured from V2A or V4A steel, that is material which is not only expensive but can only be shaped and worked with considerable difficulty due to its hardness. Because the rod-shaped element can be made separately from the expander element by resorting to the above-mentioned possibility of releasably connecting them via screw threads, these elements can be manufactured individually, avoiding the necessity for utilizing a large-diameter rod and removing material from it in such a manner as to obtain over most of its length a small diameter corresponding to the desired diameter for the rod-shaped element, whereas a remaining portion having the original larger diameter will constitute the expander element. This is of course a possibility, but due to the difficulty of working the type of steel here in question, of which the components of the device according to the present invention are advantageously made, the solution of being able to make the rod-shaped element and the expander element separately and connecting them to one another is currently preferred because it is less expensive.

It is also proposed according to the present invention to provide an extension rod which can be threaded into a tapped bore provided in the rear endface of the rod-shaped element. The extension rod should have a diameter corresponding to that of the rod-shaped element itself, and it is advantageous if its threads provided on its outer surface are also the same as those on the rear end of the rod-shaped element and can mesh with the threads of the cap nut which is effectively used for moving the rod-shaped element relative to the tube. However, it is also possible to so construct the extension rod that it can be threaded onto the threads of the rear portion of the rod-shaped element if this is desired, and in either case, the provision of such an extension permits the surgeon the complete insertion of the at least the major portion of the threaded rod-shaped element into the bone marrow cavity without difficulty, whereupon the extension rod can then be removed if desired or necessary.

Insofar as the second embodiment is concerned which was briefly outlined above, it should be understood that here again the bone fragments can be pre-aligned before the device is used to connect them. In this case, however, a conventional pin which in the prior art was used for connecting such bone fragments to one another, can be inserted into the bone marrow cavity to fix the bone fragments with reference to one another against relative displacement. Thereafter the tube is pushed over the pin into the bone marrow cavity, while the bone fragments are held by the pin against relative displacement. The pin is now withdrawn and the rod-shaped element is inserted into the tube. The rod-shaped element can be given a small cross section so that it can contact the inner surface of the curved tube over a relatively large surface area. At least the intermediate portion of the rod-shaped element is of such cross-section or diameter that the rod-shaped element has sufficient flexibility or elasticity to permit it to be angularly displaced in the curved tube to an extent sufficient to permit engagement of the front portion of the rod-shaped element with the expander element located at the front of the tube, in the region of the expansible element.

However, if the rod-shaped element is constructed in this manner, its torsional strength is not sufficient to permit proper drawing-in of the expander element into the expansible element. On the other hand, its tensile strength is fully sufficient for this purpose and the invention therefore provides for use of a cap nut or sleeve which is engageable with a rear threaded end portion of the rod-shaped element and which, when turned in requisite sense, will cause the rod-shaped element to perform a movement in the tube which is purely axially of the tube, whereby the rod-shaped element is subjected only to tensile forces in drawing the expander element into the expansible element.

The rod-shaped element may be provided at its front end with coupling portions capable of engagement with similar coupling portions on the expander element, for instance oppositely located projections which can be inserted through a corresponding aperture in the expander element and are engageable with the latter after the rod-shaped element performs a 90.degree. turn with reference to the expander element. This construction is advantageous because it requires angular displacement of the rod-shaped element only through about 90.degree., whereas a threaded connection between the rod-shaped element and the expander element would require at least two or three complete turns of the rod-shaped element, which would have to result in the engagement of at least two or three threads on the rod-shaped element with threads on the expander element in order to take up the necessary tensile force. Evidently, the possibility outlined above is preferable under the circumstances, although the use of threads is not to be excluded.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an axial section through a tubular bone with a device according to the present invention inserted into it;

FIG. 2 is a fragmentary axial section illustrating a component of the device in FIG. 1;

FIG. 3 is a view similar to FIG. 1 illustrating a further embodiment of the invention; and

FIG. 4 illustrates another concept of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Discussing the drawing in detail, and firstly referring to FIGS. 1 and 2 thereof, it will be seen that the device is generally identified with reference numeral 1 and is advantageously produced in all its components of V2A or V4A steel. It has an elongated supporting tube or sleeve 2 to the front end of which is mounted an expansible element 3 of known construction. In utilizing this device the bone fragments 12 are first aligned by pushing the threaded rod-shaped element 5 into the longitudinally extending curved bone marrow cavity 18, thereby assuring that the bone fragments 12 are aligned in longitudinal direction at the surface of the fracture 13.

Once the rod-shaped element 5 has been so inserted, the tube 2 with the expansion member 6 accomodated in the expansible element 3 and provided with an axial passage, is slipped over the rod-shaped element 5 and inserted into the bone marrow cavity 18 until the element 6 contacts the enlargement 20 provided at the front end portion of the element 5.

When, now, the element 5 is shifted in axially rearward direction of the tube 2, for instance by means of an internally threaded cap sleeve 4 which is threaded onto the rod-shaped element 5 at the rear end thereof, and is guided in a widened portion 7 at the rear end of the passage of the tube 2, the sleeve 4 will bear against a shoulder 8 or else the rear end of the tube 2, so that upon its rotation it will draw the element 5 rearwardly with the result that the portion 20 will bear against the member 6, moving the same into the element 3 and causing the latter to spread outwardly and become anchored in the bone marrow cavity.

It is advantageous for the axial length of the member 4 to be so calculated that when the rod-shaped element 5 has been withdrawn rearwardly to the extent necessary to effect full expansion of the element 3, its rear end will be sufficiently forwardly spaced from the rear end of the member 4 to permit a cap screw 9 to be threaded into this rear end, closing it. The cap screw 9 has a head 10 abutting against the annular disc 11.

Projections 14 are provided on the member 6 and guided in slots which extend longitudinally of the element 3 to prevent relative angular displacement of the member 6 and the element 3. The element 3, incidentally, can be threaded into an internal thread 17 provided at the front end of the sleeve 2 by means of an exterior thread 16 provided on the element 3.

It will be seen in FIG. 2 that the rod 5 will be constructed from several parts, namely a portion 21 carrying the portion 20 and provided with an internal thread 22 into which another portion 23 may be threaded by means of an externally threaded part 24. At the rear end the rod 5 may be extended by a further portion 25 which is threadedly connected with it in the manner illustrated for the purposes outlined earlier.

Coming to the embodiment illustrated in FIG. 3 it will be seen that there we have shown a device wherein the tube 2 (it should be noted that like reference numerals identify like elements as in FIGS. 1 and 2) can be pushed over a pin which is temporarily inserted into the bone marrow cavity to provide for temporary and preliminary fixation of the bone fragments 12. In this embodiment the member 6 is located in a recess at the forward end of the device, being provided with an internal thread 30, the root diameter of which is slightly larger than the outside diameter of the pin which is to be used for the preliminary fixation of the bone fragments. Once the pin has been inserted, the tube 2 is pushed over to the maximum extent desired, and thereupon the pin (which is not shown) is withdrawn. Now, the rod-shaped element 5 is inserted into the tube 2 and in this embodiment the element 5 is provided at least in its intermediate portion of a cross-section so selected that it can be angularly displaced within the tube 2, that is that it is sufficiently flexible to permit such turning. This is necessary to permit connection of the member 6 with the element 5. The element 5 may adapt itself to the curvature of the tube 2 during insertion and during angular displacement due to the sufficient elasticity resulting from its small cross-section at least at the intermediate portion.

The intermediate portion is identified with reference numeral 32 and bounded by a threaded portion 33 to which a cap nut of sleeve shaped configuration and identified with reference numeral 34 is to be secured. At the forward end of the rod-shaped element 5 the latter is provided with a threaded portion 31 which can be threaded into the internal thread 30 of the member 6 as a result of the angular displacement of the rod-shaped element 5 in the tube 2.

However, as shown in FIG. 4, it is also possible -- and believed currently to be preferable -- to provide for a different way of connecting the member 6 with the element 5. The forward end portion of the element 5 is provided with projections, preferably two opposite projections 40, constituting a lacking portion that may be passed through a corresponding aperture 41 provided in member 6 for this purpose. After such insertion the rod-shaped element 5 is turned through approximately 90.degree., whereupon the projections 40 engage the member 6 as illustrated and when the rod-shaped element 5 is then drawn axially through the tube 2, the member 6 is taken along to expand the element 3.

Additional recesses are provided at forwardly directed front side of the member 6, being offset through 90.degree. with respect to the aperture 41, so that the projections 40 can engage in and become locked in these recesses 42 to thereby assure that the element 5 cannot twist with reference to the member 6, and vice versa.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a connector for fractured tubular bones, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge readily adapt it for various applications without omitting features that from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

Claims

We claim:

1. A supporting device for fractured tubular bones having a longitudinally extending interior cavity, comprising an elongated rod-shaped element adapted to be inserted with clearance into the cavity and having a trailing end portion and a leading end portion; an expander element provided on said leading end portion; an elongated supporting tube dimensioned to fit over said rod-shaped element and adapted to be inserted into the cavity by sliding over said rear end portion and onto said rod-shaped element; an expansible element; cooperating coupling portions on said expansible element and on the front end of said tube for releasably connecting said expansible element to said tube so that said expansible element abuts against said expander element when said tube is slid over said rod-shaped element; and moving means for moving said rod-shaped element in said tube axially of the same and rearwardly away from said first end so as to draw said expander element into and thereby expand said expansible element.

2. A device as defined in claim 2, wherein said coupling portions are mating screw threads.

3. A device as defined in claim 1, said moving means comprising a nut having internal screw threads; and further comprising an extension rod having a diameter not exceeding that of said rod-shaped element and connectable with said trailing end portion of the latter, said extension rod and said trailing end portion having external screw threads adapted to mesh with said internal screw threads.

4. A device as defined in claim 1, wherein at least some of said elements and means are of rust-free steel.

5. A supporting device for fractured tubular bones having a longitudinally extending curved interior cavity, comprising an elongated curved supporting tube element adapted for insertion into said cavity longitudinally thereof and having a leading end portion; an expansible element provided on said leading end portion; an expander element for expanding said expansible element; a rod-shaped element dimensioned to be receivable in said tube element and having a front portion, a rear portion, and an intermediate portion with at least the latter having a cross-section dimensioned to permit angular displacement of said rod-shaped element in said tube element; cooperating coupling portions on said expander element and front portion for effecting coupling of said expander element to said rod-shaped element in response to angular displacement of the latter; and moving means for moving said rod-shaped element in said tube rearwardly of said leading end portion so as to effect expansion of said expansible element with said expander element.

6. A device as defined in claim 5, said expander element having an opening, and said coupling portions being transverse projections on said front portion and engaging surfaces in the region of said opening, said engaging surfaces being engageable with said projections when said front portion is inserted into said opening and said rod-shaped element is angularly displaced.

7. A device as defined in claim 6, wherein said projections are diametrically opposite one another.

8. A device as defined in claim 7, said expander element being provided in the region of said opening with a pair of diametrally opposite recesses each bounded in part by one of said engaging surfaces.

9. A device as defined in claim 8, said opening having one end into which said front portion is insertable, and an other end bounded by an endface extending transversely to the axis of said opening; and wherein said recesses are provided in said endface.