GB2041755A - Circulation augmenting hip prosthesis - Google Patents

Abstract

There is disclosed a circulation augmenting hip prosthesis including an elongated nail plate (13) formed with a plurality of fastener receiving bores and having a femoral nail (15) projecting therefrom at an angle of substantially 135 degrees, such nail being optionally hollow and being formed with a plurality of elongated, spaced apart slots (18) for circulation therethrough to supply blood to the femoral neck during the healing process. <IMAGE>

Description

SPECIFICATION Circulation augmenting hip prosthesis This invention relates to a circulation augmenting hip prosthesis for fixation of intertrochanteric or femoral neck fractures.

Further the fixation of intertrochanteric or femoral neck fractures, nails and screws have been proposed for holding the fractured parts in their correct position during the healing stages.

One of the inherent characteristics of the femoral neck and head is that blood supply thereto is extremely restricted thus rendering the heaiing of fractures in that area an extremely slow process.

Thus, post-operative recovery is frequently delayed as a result of solid nails or screws being inserted in the intramedullary trochanteric canal which restricts the circulatory status in the area of the fracture thus resulting in slow reunion of the fractured bone pieces.

The invention provides a circulation augmenting hip prosthesis comprising: an elongated nail plate formed with a plurality of fastener receiving holes; a femoral nail projecting from said plate at an angle of substantially 135 degrees therefrom; and, said nail being formed with a plurality of transverse through longitudinally elongated slots spaced along said nail for communication therethrough from one side of the other side of said nail.

A number of embodiments of circulation augmenting hip prosthesis according to the invention will now be described by way of example and with reference to the accompanying drawings in which:~ Figure 1 is a perspective view of a first embodiment; Figure 2 is a transverse sectional view taken along the line 2-2 of Figure 1; Figure 3 is a transverse sectional view similar to Figure 2, but of a second embodiment; Figure 4 is a transverse sectional view similar to Figure 2, but of a third embodiment; Figure 5 is a transverse sectional view similar to Figure 2, but of a further embodiment; Figure 6 is anterior view, in enlarged scale, of the circulation augmenting hip prosthesis in Figure 1 as implanted in a trochanter; and, Figure 7 is a sectional view of the trochanter shown in Figure 6.

Referring to FIG. 1, the circulation augmenting hip prosthesis includes generally a nail plate 13 having a nail 15 projecting transversely therefrom at an angle of about 135 degrees. The nail 15 is formed with a plurality of elongated circulation augmenting slots 18, spaced longitudinally there along for receipt there into fragments or scrapings of cortical bone and for flow there across and there along of blood. Consequently, the circulation augmenting hip prosthesis of the present invention may be installed by drilling a bore 17 (FIG. 6) through the cortical bone forming the lateral wall of the greater trochanter 20 for telescoping there through of the nail 1 5 and into the intramedulary canal of the femoral neck 23.

The circulation augmenting hip prosthesis is intended for fixing a fracture 21 of the femoral neck 23, and includes the nail plate 13 which may be affixed to the convex subtrochanteric lateral surface of the femoral shaft 35. The nail plate 13 may be formed with vertically spaced apart through bores 39 for receipt of fixation screws 41 which are inserted there through and screwed into the femoral shaft 35.

The nail 15 itself may take many different configurations in cross-sectional form, it only being important that the longitudinally elongated transverse slots 18 formed therein, project entirely there through for transverse communication there through to enhance the healing of the fracture site.

The cross-sectional configuration of the rod 1 5 shown in FIGS. 1 and 2 is somewhat of a modified I-beam, laid transversely to the direction of the load bearing plane and is formed on its opposite sides with somewhat circular in cross-section rods 45 and 47 connected together by a thick central web 50 which has the elongated slots 18 formed therein (FIG. 2).

Referring to FIG. 1, a semi-circular crown flange 55 is formed at the lateral outer extremity of the nail 15 and angles upwardly and laterally outwardly therefrom at an angle of approximately 90 degrees thereto to compliment the angle of the lateral outer surface of the major trochanter 20 (FIG 6).

In operation, when the circulation augmenting hip prosthesis is to be implanted the hip pinning operation may be performed in the desired conventional manner with an incision made over the fracture site and holes 17 drilled in the lateral surface of the trochanter 20. The nail 1 5 may then be driven up the intramedullary canal of the femoral neck 23 to span the fracture site 21 and fix the femoral head 61 relative to the intertrochanter 63 to maintain the fracture site 21 immobile. The nail plate 13 is then secured to the lateral surface of the femoral shaft 35 by means of a plurality of bone screws 41 to affix the nail 15 relative to the femoral shaft.

In this manner, it will be appreciated that the circulation slots 18 will receive some of the cortical bone fragments and shavings freed from the wall of the intramedullary canal during implantation thereof to decrease the intercortical pressure in the medullary canal of the trochanteral neck and may salvage some of the osteocytels while augmenting blood circulation transversely from one side of the femoral neck cortex to the other side of the femoral neck. This cortex may well augment circulation from 25 to 30 percent, thus speeding earlier callus of the intertrochanteric fracture.Not only will the cortical bone be free to shift within the medullary canal and into the circulation enhancing slots 18 to thus relieve intercortical pressure, but slots will serve as cavities for receipt of blood collected from hemorrhaging about the fracture site to thus further retard such pressure buildup.

The embodiment of the circulation augmenting prosthesis shown in FIG. 3 is substantially the same as that shown in FIGS. 1 and 2, except that the nail 71 is hollow to form a longitudinal interior passage 73 for longitudinal communication between the transverse communication slots 75, corresponding with the slots 18 shown in FIG. 1.

Such longitudinal passages 73 further enhances communication transversely across the medullary canal from cortical bone to cortical bone as well as longitudinally along the medullary canal, thus promoting an even greater amount of blood circulation to the site of the fracture 21 to thus speed reunion of the bone fragments.

In the event the fracture should fail to heal sufficiently to act as a weight bearing joint, the longitudinal passage 73 may be utilized as a passage for an elongated fastening member which may be inserted for fastening an artifical femoral head to the pin 71 for replacement of the natural femoral head 61, this procedure being more fully explained in my U.S. Patent No. 3,489,143.

The cross-sectional configurations of the nails 81 and 83, shown in FIGS. 4 and 5, respectively, are further options of the cross-sections available which will provide for transverse communication through the respective communication slots 85 and 87, respectively. The nail 83 has a longitudinal passage 91 which will further enhance circulation of the fracture site by allowing for longitudinal circulation in the nail. The nail 83 is formed in cross-section with four lobes or ears 86 which are arranged in a square pattern and the walls of such nail intermediate such ears are concaved inwardly.

From the foregoing, it will be apparent that the circulation augmenting hip prosthesis of the present invention provides an economical and convenient means for fixing an intertrochanteric fracture while augmenting qirculation to the fracture site and hastening post-operative reunion of the bone fragments. Not only does the hip prosthesis of the present invention excellerate post operative reunion, but enables reunion of some fractures that would not otherwise obtain sufficient blood circulation for callus and would thus be considered a failure which may result in the necessity of a second operation to install an artifical femoral head.

Claims (8)

1. A circulation augmenting hip prosthesis comprising: an elongated nail plate formed with a plurality of fastener receiving holes; a femoral nail projecting from said plate at an angle of substantially 135 degrees therefrom; and said nail being formed with a plurality of transverse through longitudinally elongated slots spaced along said nail for communication therethrough from one side to the other side of said nail.

2. A circulation augmenting hip pin as set forth in Claim 1 wherein: said nail is formed centrally throughout substantially the full length thereof with a reduced cross-section and said openings are disposed in said reduced cross-sections.

3. A circulation augmenting hip pin as set forth in Claim 1 wherein: said nail is formed with at least three said elongated slots.

4. A circulation augmenting hip pin as set forth in Claim 1 wherein: said nail is formed with an internal longitudinal communication passage projecting between said slots.

5. A circulation augmenting hip pin as set forth in Claim 1 wherein: said nail is formed at the lateral outer extremity thereof with a crown flange projecting opposite said nail flange.

6. A circulation augmenting hip pin as set forth in Claim 1 wherein: said nail is circular in cross-section.

7. A circulation augmenting hip pin as set forth in Claim 1 wherein: said nail is hollow and is formed in crosssection with four ears arranged in a square pattern having the side walls thereof intermediate said corners concaved inwardly.

8. A circulation augmenting hip prosthesis substantially as hereinbefore described with reference to and as shown in Figures 1,2,6 and 7 or the modified form thereof as shown in any of Figures 2 to 5 of the accompanying drawings.