US3256877A

US3256877A - Adjustable nail plate joint

Info

Publication number: US3256877A
Application number: US158385A
Authority: US
Inventors: Edward J Haboush
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-12-11
Filing date: 1961-12-11
Publication date: 1966-06-21
Anticipated expiration: 1983-06-21

Description

June 21, 1966 E. J. HABOUSH ADJUSTABLE NAIL PLATE JOINT 2 Sheets-Sheet 1 Filed Dec. 11, 1961 INVENTOR EDWARD J. HABOUSH S Ma 667% m pm I S m MW 4 June 21, 1966 E. J. HABOUSH 3,256,877

ADJUSTABLE NAIL PLATE JOINT Filed Dec. 11, 1961 2 Sheets-Sheet 2 FIG.|5.

1 EDJ e3 EDWA R D A.HABOUSH HIS ATTORNEYS i United States Patent 3,256,877 ADJUSTABLE NAIL PLATE J OINT Edward J. Haboush, 59 E. 79th St, New York, N.Y. Filed Dec. 11, 1961, Ser. No. 158,385 6 Claims. (Cl. 12892) This invention relates, generally, to a new and improved nail plate for the surgical treatment of bone fractures and, in particular, to an adjustable nail and nail plate assembly for the treatment of fractures of the femur.

The treatment of fractures of the hip by internal fixation is now well known. Pins, multiple wires, and nails in various sizes were first introduced for this purpose. Soon thereafter a nail was developed that could be cut in length to eliminate the need for various sizes. Subsequently the need for nail plates for the treatment of intertrochanteric fractures, became evident and they were introduced.

In the course of time, the number of devices for the surgical treatment of bone fractures has proliferated, so that today our armamentarium includes innumerable nails and nail plates of various sizes, shapes, and angles. This has created the problem of maintaining many diverse devices and special instruments for surgical treatment of bone fractures. Any innovation that simplifies the complexity of nails and nail plates would not only reduce the steps in an operation but also diminish the length of anesthesia, morbidity and mortality.

According to this invention, a two piece nail and nail plate assembly is provided in which the nail is hingedly connected to the nail plate. A ratchet joint in the hinge transmits bending forces from the nail to the nail plate.

The ratchet joint may be made self-locking if desired.

For a better understanding of the invention, reference is made'to the following detailed description thereof and to the accompanying drawings in which:

FIGURES 1 and 2 show a preferred embodiment of this invention in which a Haboush universal nail is used for both the nail and nail plate;

FIGURES 3 through 9 show the detailed construction of the various parts of the preferred embodiment shown in FIGURES land 2;

FIGURES 10 and 11 show another preferred embodiment providing a special one-piece nail and one-piece plate;

FIGURES 12 through 17 show the detailed construction of the various parts of the embodiment shown in FIGURES 10 and 11;

FIGURES 18 to 21 illustrate the spreading tool for resetting the nail position;

FIGURES 22 and 23 illustrate an adapter to permit injection of a bone building solution; and

FIGURE 24 shows a typical nail and nail plate insertion.

Referring to FIGURES l and 2, the

reference numerals

20 and 21 designate, respectively, a nail, (adapted to be inserted through the femur and upwardly into the neck of the femur) and a plate (adapted to be attached by screws to the femoral shaft). The nail and the plate are connected to each other by means of a plate holder 22, a nail stem 23, and a ratchet joint 24 therebetween;

The nail 20 is of H beam construction, whose cross section may be seen in FIGURE 1 at 20a. The plate 21 is likewise of H beam construction. Screw holes 25 are provided in the web 26 of the plate for receiving screws 27 (of which one is shown) to attach the plate to the femoral shaft. The flanges 28 of plate 21 are oriented approximately vertically to the surface of the femoral shaft and rest thereon by edges 29. Web 26 of the plate is therefore approximately parallel to the femoral shaft.

An important part of this invention resides in the assembly for joining the nail and plate, such assembly com- 3,256,877 Patented June 21, 1966 prising a plate holder 22, nail stem 23, and ratchet joint 24. The plate holder 22, is formed of two

members

22a and 22b (FIG. 1) of which 22a is illustrated in detail in FIGURES 3, 4, 5 and 6. Member 22b is a mirror image of member 22a. As shown by FIGURES 3 and 4, member 22a is comprised of an arm 33 extending from a base 32, a plate slot 34 formed in the base, and a ratchet face 35 embossed on the inner side of the upper end of arm 33.

A detailed view of plate slot 34 is shown in FIGURE 5. The slot has a T-shaped cross section 36 and is adapted thereby to slidably engage half of the H beam section of plate 21. The mating plate holder, 22b is similarly slotted to engage the other half of the H beam plate 21. Half of a screw hole 37 (FIGS. 3 and 4) is provided in each half of the

plate holder

22a and 22b. Insertion of a screw 37a (FIG. 1) in hole 37 serves simultaneously to hold the two

halves

22a and 22b of the plate holder firmly to the plate 21.

As stated, the upper end of the arm 33 carries a ratchet face 35 comprised of radial ratchet teeth 38 formed on a circular boss 39 and projecting inwardly from arm 33. A detailed section of the radial ratchet teeth is shown in FIGURE 6 wherein a typical tooth 38 is shown.

The ratchet teeth 38 on arm 22a (FIG. 8) engage the mating ratchet teeth 44 on one side of the nail stem 23 to form half of the ratchet joint 24. The other half of the ratchet joint is formed by similar ratchet teeth in the plate holder member 22b which engages ratchet teeth formed on the other side of nail stem 23. A bending moment developed by the body weight acting on the lever arm of the nail 20 is accordingly transmitted from the nail 20 to the plate 21 by means of ratchet point 24. As shown in detail in FIGS. 7, 8 and 9, the nail stem 23 comprises a member having formed therein a boxlike channel 40 with open ends adapted to slidably engage nail 20. FIGURE 9 shows a section through this channel looking along the axis thereof. The ends 43a and 43b (FIG. 7) of the nail stem are cut at an acute angle to the axis of the channel so that they will be approximately parallel to the vertical sides of the plate holder 22 when the entire assembly is inserted in the bone. Locking means are provided rigidly engaging nail stem 23 to nail 20. A simple friction fit is sufiicient, as shown in FIGS. 1 and 2. Alternatively pins or a set-screw may be provided.

As stated, the sides of the stem 23 have ratchet teeth 44 thereon which mate with the cooperating ratchet teeth 38 of the ratchet face 35 of the plate holder. The nail stern has formed therein on opposite sides a pair of internally threaded holes 45 which receive screws 46. The screws slidably fit through unthreaded holes 47 (FIGS. 4 and 9) centrally formed in the bosses of plate holder members 22a and 2211. If desired, the screws 46 may be replaced by pins extending from the nail stem into holes 47 and having a friction fit in

holes

45 and 47. A-rms 22a and 22b springedly engage nail stem 23. Ratchet joint 24 may thereby be adjusted stepwise when screws 46 are not fully advanced into their respective holes 45. After adjusting the nail and plate to the desired angular position,

screws 46 are tightened to lock the ratchet joint 24 firmly.

When the nail and nail plate assembly is used for treatment of intertrochanteric fractures of the femur, there are substantial bending forces on the ratchet joint tending to rotate the nail clockwise relative to the nail plate. is preferable, therefore, that ratchet joint 24 be designed to prevent clockwise rotation of the nail in the event that screws 46 are accidentally loosened.

This is accomplished by using ratchet teeth having a set of faces 38a (FIGURE 6) substantially co-planar with the .axis of rotation and a set of faces 38b at an acute angle thereto. Teeth 44 on nail stem 23 have con- 15 forming faces 44a and 44b. Faces 38a ofratchet teeth 38 face counterclockwise and the corresponding faces 44a of ratchet teeth 44 face clockwise.

When the

ratchet teeth

38 and 44 are springedly engaged by

arms

22a and 22b, faces 38a and the corresponding faces 44a will engage to prevent clockwise rotation of nail 20. counterclockwise rotations of nail 20, how ever will engage the sloping faces 38b of teeth 38 and the corresponding faces 44b of teeth 44. Arms 22a and 221) will thereby be forced aside permitting rotational adjustment of the nail in the counterclockwise direction.

Another embodiment of the invention is illustrated in FIGURES -17. Referring first to FIGURES 10 and 11, shown therein is a nail 50 and a nail plate 51 joined by a ratchet joint 52.

In this embodiment, the nail plate and the nail plate holder are combined in a single integral piece 51 comprised of (FIGS. 10 and 12) a web 53 and

integral side arms

54a and 54b extending upwardly from web 53.

Arms

54a and 54b springedly engage ratchet joint 52. The

side members

54a and 54b rest substantially vertically on the femoral shaft and the web 53 is substantially parallel to the femoral shaft. Screw holes 55 are provided in the web whereby the nail plate 51 can be screwed to the femoral shaft. The upper ends of the

arms

54a, 54b, carry respective sets of

ratchet teeth

56a, 56b which mate with cooperating sets of

ratchet teeth

57a, 57b in the nail 50 to form a ratchet joint 52 similar to the already described r'atchet joint 24. Preferably spring

arms

54a and 54b extend free of web 53 from the mid-portion of the web. This permits greater flexibility in arms 54a and 5412 without requiring unduly thincross sections. Web 53 may have a concave lower surface 53a (FIG. 12) so that it will conform more closely to the femoral shaft.

Nail 50 is shown in detail in FIGURES 13, 14, and 16. The nail comprises a modified H beam section 60 which is integrally attached-to a base 61 of generally cylindrical cross section (FIG. 14).

The web 62 of H beam section 60 is of variable thickness as illustrated in the sections shown in FIGURES 15 and 16. Likewise the flanges 63 of the H beam are of variable shape. On the lower portion of the nail the flange has cylindrically shaped outer surface (FIG. 15) while on the upper portion of the nail the flanges are flat. At both ends of the cylindrical base 61 are

ratchet teeth

57a and 57b which mate with cooperating

ratchet teeth

56a and 56b of the nail plate 51. A hole 65 is drilled lengthwise through the web of the H beam, in order to accommodate a guide wire. The cylindrical base 61 is provided with a threaded hole 66 to accommodate a conventional nail driving and extracting tool..

It is known that the rate at which bone fractures heal is promoted by bone building substances such as collagen chondroitin sulfate. Accordingly transverse holes 67 are provided through the web of the nail in communication with the guide wire hole 65. Thus after insertion of the nail, the guide wire may be removed and a solution containing collagen chondroitin sulfate injected through holes Y65 and 67 (described more fully below).

Referring to FIGURE 17, the ratchet section of the nail plate holder is shown at 5612, and the ratchet section of the nail is shown at 57b. Passing horizontally through base 61 is a central internally threaded hole 68 receiving screws 69. Screws 69 engage in threadedhole 68 and provide an axis around which ratchet joint 52 may pivot. Ratchet

teeth

56a, 56b, 57a and 57b are automatically locking when the nail is rotated in a clockwise direction as described above.

The

arms

54a and 54b carrying the

ratchet teeth

57a and 57b pivot around screws 69 which fit through holes 70. Holes 70 are not threaded so that they do not engage the threads of screws 69. The

arms

54a and 54b, therefore, will always be free to spring outwardly and permit adjustment of the nail and nail plate.

Because of the self locking feature the nail is adjustable in only a counterclockwise direction. In some cases, however, it may be necessary to reset the angular position of the nail in the clockwise direction. For this purpose a spreading tool is provided which may be inserted in the space 73 (FIG. 10) between the

arms

54a and 54b. This tool is illustrated in FIGURES 18 through 21. The tool comprises a handle having a shank 74 and a crossarm 75. The bottom tip 76 of the shank 74 has an elliptical shape. A resilient, split pad 77 fits over tip 76 and is fastened thereto by a screw 78 and washer 79. As illustrated in FIG. 21 a 90 turn of the handle will rotate the elliptical tip from 76 (solid) to 76a (dotted) and thereby expand the split pad 77. When inserted in space 73, and expanded as illustrated,

arms

54a and 54b are spread, whereby ratchet joint 52 is released and the position of the nail may be freely adjusted. To avoid scratches on the nail plate which might lead to corrosion, pad 77 is preferably of a soft, plastic material which may be sterilized such as Teflon.

To inject the collagen chondroitin sulfate solution mentioned above a special adapter and a conventional hypodermic syringe is used. The adapter piece is illustrated in FIGURES 22 and 23. The adapter comprises knurled adapter member 83 having a threaded end 84 adapted to screw into hole 66 in the base of the nail. A fitting 85 is provided on the other end of the cylinder which fits a conventional hypodermic syringe (not shown).

A central hole 86 through cylindrical member 83 provides for passage of the injected fluid from the syringe to the guide hole 65 and thence to holes 67. The solution of collagen chondroitin sulfate injected may also have dissolved therein an X-ray opaque tracing compound such as a radio-opaque iodine salt to permit X-ray observation of the penetration of the collagen chondroitin sulfate.

Because scratches on the nail or nail plate tend to cause corrosion, the adapter member 83 is made of a soft, plastic material, which may be sterilized such as Teflon. Alternatively, however, hole 66 in base 61 may be provided with a Teflon insert 66a as illustrated in FIG- URE 17, and adapter 83 may be made of corrosion re= sistant alloy. If a plastic insert is provided as in hole 6611, a small shoulder is required to hold the insert in place when an extractor tool is used.

The manner in which the nail and nail plate of FIGS. 10-17 is used to treat a fracture of the femur is illustrated in FIG. 24. The nail 50 and nail plate 51, are adjusted so that the angle 88 therebetween is less than the final angle to be assumed. Nail 50 is inserted in an intermedullary position upwardly through the neck 89 of the femur until the tip 90 of the nailis imbedded' in the head 91 of the femur thereby spanning the fracture zone 92. When this is done, nail plate 51, will automatically assume the correct position. The nail plate 51 is screwed to the femoral shaft 94 by screws 95. If it is necessary to reset angle 88, the spreader tool described above is inserted into the space 73 (FIG. 10) to release the ratchet joint 52.

As mentioned above, collagen chondroitin sulfate solution may be injected to accelerate healing of the fracture. As illustrated in FIGURE 24, adapter member 83 is screwed into the base of the nail. A hypodermic syringe 96 is attached to the other end of adapter 83.

The use of the embodiment shown in FIGS. 1-9 is analogous.

An important feature of the adjustable nail plate is that the strength of the assembled device must be suflicient to support the stresses placed upon it by the human body.

I Referring to the typical adjustable nail and plate shown in FIG. 24, the body weight is assumed to act at the tip of the nail with a force F. This induces a bending movement M at the ratchet joint 52. For illustrative purposes the strength of the assembly was calculated FLg Cos a where L is the length of the nail,

h/ 2 is the radius of the cross section,

I is the moment of inertia of the cross section, and Cos at is the cosine of angle 88.

The maximum allowable stress-is 101,300 p.s.i. (ultimate tensile strength). In practice however, the maximum stress should be less than the yield point (82,300 p.s.i. in this case) and preferably less than the fatigue strength. Assuming that nail 50 is inserted upwardly through the neck of the femur at an angle of 45, the maximum force F which may be supported at the tip 90 of the nail is approximately 320 pounds at the yield strength of the materiaL' It is important that the elastic deflection below the yield point be small so that it will not interfere with the healing of the fracture. The deflection, d, may be calculated from the formula,

E is the modulus of elasticity, and 1 is the effective length for deflection Assuming an s of 82,300 p.s.i. and an 1., of about 4 in., the deflection will be about .05 in. This is acceptably small.

Similar calculations have been made for the ratchet wherein a typical tooth has a mean radius of .275 inch, and the area available for shear at the base of the tooth is .0275 square inches.

The bending moment for a 320 lb. force on a nail inserted at an angle of 45 is 1020 inch-pounds. For Haynes alloy 21, having a shear-strength of approximately 41,000 p.s.i., four ratchet teeth in contact will sustain a bending movement M of 1230 inch-pounds. The nail is designed to have at least 12 teeth in contact.

The strength and size requirements for other embodiments of this invention may be similarly calculated according to the well known principles of the strength of materials and biomechanics. In this connection, reference is made to the detailed analysis of the biomechanics of nails and nail plates which appears in the paper Biomechanics of Femoral Nail and Nail Plate Insertions in Fractures of the Neck of the Femur, Bulletin of the Hospital for Joint Diseases, volume XIV, page 125.

The above described embodiments being exemplary only, it is to be understood that additions thereto, omissions therefrom and modifications thereof can be made without departing from the spirit of the invention, and that. the invention comprehends embodiments differing in form and/or detail from these specifically disclosed herein. For example, the ratchet joint may be formed from a single pair of ratchet faces, or may comprise a single arm on the nail plate engaged by a forked member on the nail. Alternate shapes for the nail, nail plate, nail plate holder and nail stem are likewise within the spirit of this invention. Accordingly, the invention is not to be considered as limited save as is consonant with the recitals of the following claims.

I claim:

1. A surgical nail and nail plate assembly comprising a surgical nail plate, a nail plate arm attached to said nail plate having one end extending therefrom, a surgical nail, and an axle extending between the extended end of said arm and one end of said nail hingedly engaging said nail and said arm together, a first annular array of ratchet teeth on the extended end of said arm substantially coaxial with said axle, said ratchet teeth having a first set of faces substantially coplanar with said axle and a sec ond set of faces at an angle to said axle, each of said second faces extending between adjacent faces of said first set, and a second annular array of ratchet teeth on said one end of said nail mating with said first annular array of ratchet teeth, said second annular array being substantially coaxial with said axle and having a first set of faces substantially coplanar with said axle which are adapted to engage said first set of faces of said first annular array and a second set of faces in said second annular array at an angle to said axle which are adapted to slidably engage said second set of faces on said first annular array, means springedly biasing said mating ratchet teeth into interengagement with each other, said ratchet teeth and said biasing means thereby permitting said nail to be slidably and selectively adjusted in one rotational direction relative to said nail plate, and preventing rotation in the opposite rotational direction.

2. A surgical nail and nail plate assembly comprising a surgical nail plate, a pair of transversely spaced nail plates arms attached to said nail plate having transversely resilient ends extending therefrom, a surgical nail having one end interposed between the extended ends of said arms, an axle extending between said extended ends and said one end for hingedly engaging said one end and said arms to each other, first annular arrays of ratchet teeth on the extended ends of said arms coaxial with said axle, said ratchet teeth having a first set of faces substantially coplanar with said axle and a second set of faces at an angle to said axle, each of which extends between adjacent faces of said first set, and second annular arrays of ratchet teeth on said one end which mate with and engage the arrays of ratchet teeth on said arms, said second annular arrays having a first set of faces substantially coplanar with said axle and adapted to engage said first faces of said first annular array and a second set of faces at an angle with said axle adapted to slidably engagesaid second set of teeth of said first array, said interengaging ratchet teeth thereby permitting said nail to be selectively adjusted relative to said nail plate in one rotational direction and preventing rotation in the opposite rotational direction.

3. A surgical nail and nail plate assembly according to claim 2 which further comprises a pair of screws each of which pass transversely through an unthreaded hole formed in a respective one of the extended ends of said arms and each of which screws is adapted to engage a respective threaded hole formed in said one end of said nail, said screws further having means for locking mating pairs of ratchet teeth on said arm and said one end of said nail into engagement with each other when said screws are threaded into said threaded hole.

4. A nail and a nail plate assembly according to claim 2 wherein a cylindrical hub is integrally attached to said one end of said nail, on which hub are formed said second annular arrays of ratchet teeth.

5. A surgical nail and nail plate assembly according to claim 2 wherein said nail is formed with a bore running axially through the length thereof and transverse holes near the tip of said nail connecting with said axial bore, and means are provided at the base of said nail to receive a syringe, whereby an osteogenic factor may be injected through said annular bore and transverse holes to accelerate the healing of the fracture.

6. A surgical nail and nail plate assembly according to claim 2 further comprising a nail plate holder having a base slidably engaging said nail plate, said base having 7 8 locking means to engage said nail plate, and having said 2,441,765 5/ 194-8 Hopkins 12892 nail plate arms integrally formed with said base and eX- 2,500,993 3/1950 Mason 12892 tending away therefrom, the extended end of said arms, 7 having said first annular array of ratchet teeth formed FOREIGN PATENTS thereon and a nail stem slidably receiving said nail and 5 164,305 10/1949 Austria. having locking means to engage said nail, said na1l stern. 918,531 7/1949 Germany.

being hingedly engaged to the extended end of said arm by means of said axle, and having said second annular array of ratchet teeth formed thereon. RICHARD GAUDET "nary Examl'wr' References Cited by the Examiner 10 JORDAN FRANKLIN Exammer' UNITED STATES PATENTS HINEY GOLDBERCZ tE I 5 ,521 8/1896 Leger 287-14 swan xammels'

Claims

1. A SURGICAL NAIL AND NAIL PLATE ASSEMBLY COMPRISING A SURGICAL NAIL PLATE, A NAIL PLATE ARM ATTACHED TO SAID NAIL PLATE HAVING ONE END EXTENDING THEREFROM, A SURGICAL NAIL, AND AN AXLE EXTENDING BETWEEN THE EXTENDED END OF SAID ARM AND ONE END OF SAID NAIL HINGEDLY ENGAGING SAID NAIL AND SAID ARM TOGETHER, A FIRST ANNULAR ARRAY OF RATCHET TEETH ON THE EXTENDED END OF SAID ARM SUBSTANTIALLY COAXIAL WITH SAID AXLE, SAID RATCHET TEETH HAVING A FIRST SET OF FACES SUBSTANTIALLY COPLANAR WITH SAID AXLE AND A SECOND SET OF FACES AT AN ANGLE TO SAID AXLE, EACH OF SAID SECOND FACES EXTENDING BETWEEN ADJACENT FACES OF SAID FIRST SET, AND A SECOND ANNULAR ARRAY OF RATCHET TEETH ON SAID ONE END OF SAID NAIL MATING WITH SAID FIRST ANNULAR ARRAY OF RATCHET TEETH, SAID SECOND ANNULAR ARRAY BEING SUBSTANTIALLY COAXIAL WITH SAID AXLE AND HAVING A FIRST SET OF FACES SUBSTANTIALLY COPLANAR WITH SAID AXLE WHICH ARE ADAPTED TO ENGAGE SAID FIRST SET OF FACES OF SAID FIRST ANNULAR ARRAY AND A SECOND SET OF FACES IN SAID SECOND ANNULAR ARRAY AT AN ANGLE TO SAID AXLE WHICH ARE ADAPTED TO SLIDABLY ENGAGE SAID SECOND SET OF FACES ON SAID FIRST ANNULAR ARRAY, MEANS SPRINGEDLY BIASING SAID MATING RATCHET TEETH INTO INTERENGAGEMENT WITH EACH OTHER, SAID RATCHET TEETH AND SAID BIASING MEANS THEREBY PERMITTING SAID NAIL TO BE SLIDABLY AND SELECTIVELY ADJUSTED IN ONE ROTATIONAL DIRECTION RELATIVE TO SAID NAIL PLATE, AND PREVENTING ROTATION IN THE OPPOSITE ROTATIONAL DIRECTION.