US2874691A - Femoral nail - Google Patents

Description

Feb. 24, 1959 c. A. MASON 7 2,

FEMORAL NAIL V Filed Feb. 8, 1957 2 Sheets-Sheet 2 IN V EN TOR.

626845731 6456 A Mara/v (new.

United States Patent FEMORAL NAIL Christopher A. Mason, Los Angeles, Calif. Application February 8, 1957, Serial No. 639,069 Y J 9Clilil118. (Cl. 128-92) I'he present invention relates to femoral nails or hip nails, and more particularly to such a nail which affords certain procedural and functional advantages never be fore afforded by devices of this general ,type.

In. the treatment and repair of hip fractures, i. e., fractures of head of the femur, it has become common practice in the medical profession to employ a hip or femoral nail to mechanically fix the fractured fragments together to enable knitting or mending of the bone structure.

The conventional femoral nail, for use in the case of intertrochanteric and neck fractures, comprises a base plateadapted to be secured to the shaft of the thigh bone or femur, the base plate having projecting therefrom a nail portion adapted to extend through the neck of the 2,874,691 Patented Feb. 24, 1959 and until the nail is removed.

femur and into the head thereof to act as a fixation element enabling healing of the fracture or fractures, while at the same time, allowing mobility of the hip joint.

In the utilization of such nails, the surgeon, after exposing the lateral portion of the femur, approximates the angles at which he anticipates the nail portion should be inserted so as .to properly contact the head of the femur. He then forms a hole in the thin shell of hard bone on the femoral shaft and inserts the nail portion into the hole. In order for the nail to be properly directed the surgeon must have precisely estimated any angular displacementor drift of the shaft with relation to the head of the femur. Practice indicates that a skilled and-ex perienced surgeon encounters substantial difficulty in initially estimating the precise proper angle at which the nail must be inserted through the opening. Failing in this, the nail must be manipulated or the base or attachment plate will not be properly related to they femoral shaft upon driving the nail into the head; norwill the.

nail be properly positioned so as to afford strong fixation.

Withinthe thin shell of the femur is a fatty material which permits of ease of nail manipulation. .However, the nails heretofore available for this purpose, by virtue of their structure, create certain problems which render manipulation of the nail dangerous and impractical.

Prior nails of the most widely known and used types have required the formation of a rather large opening in the lateral wall of the femoral shaft. This opening of necessity being located just below the major or greater trochanter, where because of-the bone structure, the hole formation substantially and critically weakens the bony substance at a point where such weakness can be ill afforded. The hard bone shell at this point is extremely thin and the etfective area is :quite limited. When any error is made in the location of the opening, correction of the location furthercritically weakens the bone. If the prior nails are manipulated for correction of their angle and location'the bonearea surrounding the opening is caused to splinter and crack." Indeed in many instances, eiilargement of the opening in the shaft and/or manipulation of the nail in a misplaced opening have been known to cause the remaining intact bone structure to fracture during the operation or to fracture following Moreover, in some instances, if the surgeon be inaccurate in the placement of the opening, and nevertheless drives the point into the femur, the nail may not be properly placed so as to afford maximum support where such support is required, and the fixation may be ineffectual, thus necessitating further operative work to correct drift of, the femoral shaft. In addition, such drift of the shaft may cause the misplaced nail to penetrate the femur and injure the joint with resultant substantial discomfort and anxiety on the part of the patient.

Despite these hazards, however, in the use of previously known and commercially available femoral nails, once the surgeon has formed the opening, he has been more or less committed to insert the nail and drive it into the head of the femur because of his inability to stantially less area than the openings necessitated by the.

prior nails.

Another object is to provide a nail which, despite the relatively small size of the opening in the femoral shaft necessitated thereby, is capable of a wide range of universal manipulation, after it is inserted through the hole, this being extremely beneficial and enabling ex ploration subsequent to entry, without in any way causing any stresses to be set up either in the bone or in the nail structure, such as would otherwise have deleterious effects.

'As a result of the accomplishment of the just-mentioned objections, non-critical, i. e., relatively non-weakening, insertion of the nail into the femoral neck region is permitted. In addition, the direction of the nail may be corrected subsequent to insertion, without requiring the cutting of a new opening or otherwise enlarging the existing opening, with attendant weakening and possiblev fracture of the femur in the subtrochanteric region.

A further object is to provide a femoral nail structure which will preclude medial drift of the femoral shaft andnail with relation to the head of the femur; this is accomplished by providing a bearing surface extending upwardly; above the point of entrance of the nail into engagement with the greater trochanter. In addition, the bearing extension is preferably provided with an opening for accommodating or for fixing the bearing extension to the upper trochanteric fragment. support for the greater trochanter if it should be corn-v minuted or cracked, and enables the utilization of a. wire about the abductor tendon and muscles to. relieve, the

trochanter of strain therefrom. I

Still another object of the invention is to providea femoral'nail which is structurally tailored to meet the load impressed thereon when the patient is ambulatory,

Such a structure also provides.

this being accomplished by forming the nail so that it diverges and has increasing cross-sectional mass towards the junction of the nail portion and the base or attachment plate, thisplate also increasing in cross-sectional.

area from its opposite ends towards the 'union, with the blade portion, whereby maximum strength is afforded at the point where maximum stress is imposed due to vertical loading, namely, at the juncture of the nail portion and the base plate. I

A further object is to provide a femoral nail having a base plate which is constructed so as to conform to the shape of the femur both in a longitudinal direction and in a lateral direction, thus further facilitating a strong fixation.

In accordance with the foregoing general objectives, it is a further and specific object to provide a femoral nail structure, having a base or attachmentplate adapted to conform to the shape of the femur, this plate having a blade-like nail portion projecting angularly therefrom at an angleon the order of from approximately 125 to 135 but, for example, an angle approximately 127 has been found in practice to be particularly desirable, this blade being of a relatively thin transverse section but of substantial vertical section, and having at its free end a superior transversely extended flange, the outer extremity of the blade being sharpened to facilitate its entry into the hard bony substance of a femoral head, and said plate having a trochanteric region-supporting extension adapted to receive trochanter-engaging fastening means in the form of a screw adapted to be inserted into the trochanter or a wire or the like adapted to tie down the abductor tendon and muscles to relieve the trochanter of strain; said nail portion being insertable into the canal of the femoral neck through a relatively narrow longitudinally Fig. 1 is a view in perspective, showing a femoral nail made in accordance with the invention;

Fig. 2 is a view showing in side elevation a femoral nail embodying the invention, in applied relation in a femur bone which is shown in vertical section taken laterally therethrough, and showing a conventional driver tool applied to the nail;

Fig. 3 is a view in elevation, showing the lateral femur I formation with the nail hereof inserted therein;

Fig. 4 is a view in section, as taken on the line 44 of Fig. 2; v

Fig. 5 is a View in section, somewhat similar to the section of Fig. 4, but showing the shaft fragment of the femur in angularly displaced relation to the neck and head of the femur, with the point of the nail hereof disposed in a proper position prior to driving the nail;

Fig. 6 is a view showing in vertical section a fractured femur, where the shaft fragment and the neck and head fragment are angularly displaced, and showing in broken lines the nail hereof in different positions which it may assume during exploration of the femur prior to driving the nail; and

Fig. 7 is a fragmentary view in section, particularly showing the major trochanter supporting extension of the base plate, with a screw aflixing the extension to the trochanter.

Like reference characters in the several figures of the drawings and in the following detailed description designate corresponding parts.

Referring particularly to Fig. 1 of the drawings, the femoral nail hereof, as shown in this illustrative embodiment, comprises a generally longitudinally extended base or attachment plate 1 having a nail portion generally designated 2 projecting therefrom at an oblique angle. This angle may range from on the order of from approximately 125 to 135, but in practice it has been found that the angle should be preferably on the order of about 127, this being the most effective angle in view of the structural features to be hereinafter described.

The nail portion 2 is relatively thin and substantially fiat from the juncture of the nail portion to its extreme free end, thus providing a blade-like section as at 3. The upper marginal edge 4 of the nail portion is preferably straight, and the lower marginal edge 5 is also preferably straight and disposed at a slightangle with relation to the edge top 4, so that the nail portion tapers from the junction thereof with the base plate towards the free end. structurally, this provides a nail portion which offers only a minimum of resistance to bone penetration,.but

which has a substantial mass of material at the juncture with the base plate to thereby afford more than adequate strength to support load imposed thereon at the point of maximum stress.

At the free end of the nail portion 2, it is substantially T-shaped in cross section, thus providing a load-supportingiflange 6 which projects laterally withrespect to the blade-like section 3. This flange 6 is also preferably flat transversely and relatively thin'so as to offer a minimum of resistance to bone penetration. Longitudinally of the blade-like section 3 of the nail portion 2, the flange 6 terminates in spaced relation to the base plate 1 so as to leave between the flange 6 and the plate 1 an unobstructed blade-like section for a purpose which will hereinafter appear. If desired, the flange 6 may also be longitudinally tapered and may extend closer to the'plate 1 than as shown herein, as may be desired in practice.

In the illustrative embodiment, the juncture of the nail p0rtion2 with the blade 1 includes a recess or socket 1' in the plate 1 adapted to receive the end 2' of the nail portion 2. Securing of the blade-like end 2 in the recess 1' may be accomplished by welding. However, in practice the nail may be forged as an integral structure, or any other suitable method of joining the plate and nail portion'with a strong supporting union may be resortedto.

As previously mentioned the thincross-sectional form of the flange 6 and the blade-like section. 3 of the nail portion, as well as the longitudinal taper of the blade-like section 3, facilitate bone penetration. In addition, in

, order tofurther enable ease of penetration, the freeend of the blade-like section 3 and the outer extremity of the flangeo may be sharpened as at 7 to provide a sharp penetrating, advancing edge formation.

The plate lhas an elongated tail 8 depending from the juncture of the plate and nail portion 2, this tail preferably tapering axially towards its lower or free end and being of diminishing thickness. Any desiredor suitable number of openings 9, adapted to receive bone screws, are formed in the tail 8. In-addition, the plate 1 has an upwardly arched head extension which also tapers axially "towards its free end and is preferably of diminishing asseen in Figs. 2 and 6 longitudinally arched slightly so as to conform to the average femur.

The structural characteristics alleviate the problems noted at the commencement hereof as will best be understood upon reference to the nail of the invention as shown in relation to a femur generally designated F in Figs..2 through 7.

Particularly referring to Figs. 2 and 3 for-thezmoment, the femur F, as is customary, includes a shaft S, at the upper end of which is a neck LN projecting at an oblique angle on the order of 125more or less from the shaft. At the free end of the neck is a ball-like head H. At the juncture of the shaft with the neck is an upper laterally projecting enlargement or protuberance referred to as the major trochanter MT and a lower small projection or protuberance T known as a minor trochanter. The shaft S comprises an outer comparatively strong and thick wall of bone having an axial canal filled with a fatty soft substance or marrow. As the wall of bone extends upwardly into the subtrochanteric lateralarea beneath the major or greater trochanter, it thins substantially to the point where it is quite weak, this weak shell of bone extending aboutthe major trochanter. The inner bone wall in the vicinity of the minor trochanter T is comparatively thick and strong since it must stand up under stress applied thereto from the head H which is adapted to be universally disposed in the human hip socket. The soft fatty marrow extends through the shaft S and fills the intertrochantery cavity and the neck of the femur, but the head H is com.- posed of solid bone back approximately as far as its union with the neck N. This bone structure is all clearly'seen in Fig. 2. r p

The nail of this invention is particularly suited for use as a fixation element for securing femoral fragments together resulting from neck fractures as indicated by the line 12 across the neck N as seen in Fig. 2, and resulting from intertrochanteric fractures as indicated by the line 13 in Fig. 2. These types of fractures as well as an infinite number of others may occur, and it is to be understood that the invention is not limited to use with such fractures alone.

In nailing the femur as shownin Figs. 2 and 4, a relatively narrow elongated slot 14 is formed in the relatively thin, weak subtrochanteric lateral wall of the femur. When conventional prior nails are used a broad opening is required, and as seen in Fig. 4 this portion of the femur affords little effective surface since the shaft S at this vicinity is formed on a relatively short radius. Accordingly, the formation of a narrow slot 14 is highly desirable since a comparatively minor proportion of the already weak bone area is removed. I

Any desired operative procedure may be followed in making the slot, but preferably (see Fig. 3) a line of small holes 15 are drilled in the crest of the. shaft and a gouging cutter is employed to remove the rough edges of the opening thus forming the smooth-Walled slot 14 to permit insertion of the blade-like section 3 of the nail portion 2 as previously described in the neck cavity. For allowing insertion of the T-head or 'flange 6, a pair of additional holes 16 may be drilled and the edges gouged so that the slot 14 is substantially T-shaped. In practice, the slot 14 need be only slightly Wider than the blade-like nail section 3.

Frequently, a fracture such as illustratively represented at 13 in Fig. 2, before fixation, will result in angular displacement of the shaft fragment Swith relation to the remainder of the femur, as shown in Fig. 5. In addition, as shown in Fig. 6, a lateral-breach may occur. Thus, in the use of prior nails, substantial risk was involved in forming the nail receiving hole or opening in the lateral wall of the femoral shaft. Once the hole was formed, the surgeon had committed himself to entering the nail in a given direction. If an error was involved, he either had to bend the nail plate or remake the hole, both of which circumstances are highly undesirable as previously mentioned.

However, with the improved nail hereof, cutting of the slot 14 does not fix the direction of the nail portion 2. Universal adjustment or manipulation of the nail is permitted because of the thin blade-like section 3 being disposed in the slot 14 with some lateral clearance and because of the extreme thinness of the bone wall, since there is no interference with such movement. Accordingly, the nail portion 2 may be angularly disposed with relation to the slot 14 in a horizontal plane, so that the point 7 is directed towards a proper insertion. Thereafter the shaft fragment may be forced into position without breaking the thin bone wall through which the 'bone extends, and without bending or otherwise stressing the nail.

Furthermore, the nail is capable of a wide range of angular adjustment in a generally vertical plane by virtue of the elongate form "of the slot 14 which does not weaken the bone shell. A proper insertion angle, therefore may also be sought or fished for .to allow for the lateral breech as shown in Fig. 6.

After such exploratory work and adjustment is accomplished the free end of the nail is driven into the hard bony head H to effect fixation of the fracture. This is preferably accomplished by the employment of a driver. A conventional driver 17 is shown in Fig. 2. This driver 17 includes an elongated shank 18 having an enlarged head '19 at its free end, and having a foot 20 at its other end. The shank 18 is notched as at 21 adjacent to the foot 20 to receive a nut 22, and a thumb screw 23, having threaded engagement in a threaded opening 24 in the nail plate 1, extends through axially aligned openings 25 and 26 in the driver shank 18 and foot 20 respectively, and is locked 'by the nut 22. It will be noted that the axis of the driver 17 and consequently the line of thrust there from is aligned with the axis of the nail portion 2.

' When the nail is driven tightly into the femur so that the plate engages the femoral shaft and the driver 17 is removed from the nail in the obvious manner, screws 9', 9 are inserted through the screw holes 9 in the tail 8 of the plate 1 and through the shank S into threaded engagement with the bony shell opposite the plate.

A further distinct advantage of the nail hereof derived from the need for only a thin elongated slot is the fact that the slot need not be precisely located in a vertical direction. Thus, some latitude is provided for avoiding a fracture line as shown in Fig. 3 when forming the slot 14. On the other hand however, because the slot is narrow and requires removal of only small bone area the crack'may be bridged by the slot 14 without adverse effects such as are encountered in forming large nail openings for prior nails.

According to one of the salient features of the invention, the upward extension 10 of the plate 1 provides bearing contact with the upper or major trochanter MT,

this extension 10 being somewhat arched as shown for this purpose. The extension 10 is also provided with a screw recess designated 27 which has its axis normal to the general plane of the bearing surface. Valuable and heretofore unobtainable advantages are derived from this structure. Among the advantages is the provision of means for providing an upper fixation point for the plate 1, as by inserting ascrew for aiding in securing the anterior and posterior fragments together against relative drift in the case of a fracture such as shown at 13 which extends down through the trochanter MT and downwardly through the subtrochanteric shaft region at an angle from the posterior to the anterior sides of the femur. This precludes the application of transverse stress to the nail portion 2. Additionally, when necessary, as in the case of a comminuted trochanter MT, a wire (not shown) may be tied to the screw 28, or in the opening 27 in the absence of such a screw, this wire being useful in tying down the abductor muscles which tend to pull upwardly on the comminuted trochanteric fragments.

In view of the foregoing it will be apparent to those skilled in the ant to which the invention appertains that substantial improvements have been provided thereby, with the result that fractured hip bones or femurs can now be joined mechanically, uniformly and effectively by virtue of the universal adjustability of the present nail subsequent to entry into the femoral neck cavity, the improved conformal plate structure including means for applying securing elements to the major trochanter, and the structural rigidity of the nail hereof, all of which features not only facilitate the application'of'a nail to a fractured femur but also improve the post=operative results. i

I claim:

1. A femoral nail comprising a longitudinally extended base plate adapted to be attached to the subtrochanteric lateral surface of a femoral shaft, and a nail portion projecting at an obliqueangle from said base plate, said nail portion being flat and relatively thin in transverse crosssection at the juncture of the nail portion with the base plate and being relatively substantial in cross-section longitudinally of said base plate so as to provide a strong load supporting union with the base plate, and said nail portion having a laterally extended load supporting flange running from the free end of the nail portion to a point spaced from said base plate, whereby said nail is universally manipulative in a relatively narrow opening in the subtrochanteric shaft portion of a femur. 7

2. A femoral nail comprising a longitudinally extended base plate adapted to be attached to the subtrochanteric lateral surface of a femoral shaft, and a nail portion projecting at an oblique angle from said base plate, said nail portion being fiat and relatively thin in transverse cross-section at the juncture of the nail portion with the base plate and being relatively substantial in cross-section longitudinally of said base plate so as to provide a strong load supporting union with the base plate, and said nail portion having a load-supporting flange thereon projecting generally laterally from opposite sides thereof and running from the free end of said nail portion to a point spaced from said base plate, whereby said nail is universally manipulative in a relatively narrow opening in the subtrachanteric shaft portion of a femur.

3. A femoral nail comprising a longitudinally extended base plate adapted to be attached to the subtrochanteric lateral shaft portion of a femur, and a thin, fiat nail portion extending at an oblique angle outwardly from the shaft-engaging face of said base plate, said nail portion having a laterally projecting load-supporting portion adjacent to its free end, said load-supporting portion extending towards said base plate and terminating in spaced relation thereto.

4. A femoral nail comprising a longitudinally extended base plate adapted to be attached to the subtrochanteric lateral shaft portion ofa femur, and a thin, flat nail portion extending at an'oblique angle outwardly from the shaft-engaging faceof said base plate, said nail portion having a laterally projecting load-supporting portion adjacent to its free end, said load-supporting portion extending towards said base plate and-terminating in spaced relationthereto, said base platebeing'relatively wide and thick providing maximurn'mass in the area of the juncture of the base plate with the nail portion, and said base plate having a stabilizing depending tail taperedlongitudinally towards its free extremity.

5. A femoral nail comprising a longitudinally extended base plate adapted to be attached to the subtrochanteric lateral shaft portion of a femur, and a thin, fiat nail portion extending at an oblique angle outwardly from the shaft-engaging face of said base plate, said nail portion having a laterally projecting load-supporting portion adjacent to its free end, said load-supporting portion extending towards said base plate and terminating in spaced relation thereto, said base plate including a tail portion depending from the area of the juncture of the nail portion with the base plate, and said base plate also including an upwardly projecting arched bearing projection for engagement with the major trochanter.

6. A femoral nail comprising a base plate adaptedto be's e'cured to thesubtrochanteric region of a femoral shaft, and a nail portion projecting from said base plate at/an oblique Tangle -for'insertion into the neck of the femun'said base' plate'having opposite terminal portions extendingElongitudinally from the juncture of said nail portion with the base'plate, one of said terminal portions constituting aitail a dapted' to extend longitudinally in close cohtac'tzwith' the femoral shaft and the other terminal portion constitutingn'a head for supporting engagement with and-fixation to the greater trochanter of the femur, said head having an opening for enabling attachment of the head to the trochanter, said head being arched longitudinallyand having a rectilinear bearing surface, said opening in the head having its axis disposed normal to said rectilinear bearing surface.

7. A femoral nail comprising a longitudinally extended base plate adapted to be secured to the subtrochanteric region of a femoral shaft, and a nail portion projecting from said base plate at an oblique angle, said nail portion having a free end of substantially a T-section, said nail portion also having a blade-like section intermediate said free end and the juncture of the blade portion with the base plate, said blade-like section being thin and flat in a direction longitudinally of the base plate, whereby said nail is universally manipulative upon insertion thereof into the neckof a femur through a relatively narrow slot extending longitudinally of the subtrochanteric region of the femoral shaft.

8. A femoral nail comprising a longitudinally extended base plate adapted to be secured to the subtrochanteric region of a femoral shaft, and a nail portion projecting from said base plate at an oblique angle, said nail portion having a free end of substantially a T-section, said nail portion also having a blade-like section intermediate said free end and the juncture of the blade portion with the base plate, said blade-like section being thin and flat in a direction longitudinally of the base plate, whereby said nail is universally manipulative upon insertion thereof into the neck of a femur through a relatively narrow slot extending longitudinally of the subtrochanteric region of the femoral shaft, said base plate being arched transversely and longitudinally to conform to the shape of the femur.

9. In a femoral nail having a plate adapted to be secured to the subtrochanteric region of a femoral shaft and a nail portion projecting therefrom at an oblique angle, said nail portion being insertable into the neck of the femur through an opening in the subtrochanteric femoral shaft, that improvement wherein said nail portion at the juncture thereof with said plate is thin and fiat with relation to the plate for enabling universal manipulation of said nail upon insertion thereof through a narrow elongated slot in the subtrochanteric region, said nail portion having a horizontal superior flange extending from the free end of the nail portion towards said plate.

References Cited in the file of this patent UNITED STATES PATENTS 2,500,370 McKibbin Mar. 14, 1950 2,699,774 Livingston Jan. 18, 1955 FOREIGN PATENTS 757,951 Germany Nov. 9, 1953 OTHER REFERENCES Y Fracture Appliances; Depuy Manufacturing Co., Inc., June 25, 1954; pp. 124 and 74; copy in Scientific Library.

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