US2579968A - Medullary pin - Google Patents

Description

L. V. RUSH MEDULLARY PIN Dec. 25, 1951 2 SHEETS-SHEET l Filed Feb. 15, 1949 l.. V. RUSH MEDULLARY PIN Dec. 25, `1951 2 SHEETS-SHEET 2 Filed Feb. l5, 1949 gmc/Mofo ATTOR N EY Patented Dec. 25, 1951 UNITED STATES 0F ICE MEDLLARY rnv,

Leslie V-l Rush, Meridian, Miss; Applicaticniiebruary 15, 1949.,.seriaiNo. 76,552

(Cl.v 12S-92) t Claims.

i 1i 'Ihislinvention relates to fracture fixing' pins for the ihtramedul'lary iixaton of fractures of the. long. bones.

' Pins of the character stated are driven into 'the'. medullary cavityof a fractured. bone. to securely hold the fracturedv portions iniirrn contactwhile knitting,.thereby reducing the necessity of immobilzing., an injured'r extremity" by casts, splints or other apparatus.

Applicant 'is aware that att'einiitsfV have.A been madeA to'employ pinsdrivenlongitudinally of.` a bone and. traversngithe area of fracture., Howy.eversuclfi pins. asvwere heretofore devisedhave .rnotlvbeen` entirely satisfactory,4 particularly when entrance tothev medullary cavity.A must be. made through an oblique opening in the cortex.: Under such circumstances, the pin has a tendency to penetrate the cortex on the opposite vside ofA the bone. andpassv intothegsoft tissue.v

An object of the present invention. isv to provide animproved pin.. of the character stated,

Which may be driven into the medulary canal andalong the. same fromany indicated startirg-v point and at Variousv angleswith minimal dangerV of, penetrating. or injuring the cortex beyond the initial point of entry.

AY` further object of the invention. is to provide a pin asmentioned havingmeans to prevent j pin from migratingA into thev bone While. in

use.`

A l`further object ofthe invention is to. provide i axing. pin formed with means whereby the pin be axiallyfrotatedi, when necessarywhi1e beingvdri-ven into position to maintain the pin in, thev desired path; and'which Will also serve as means to aid in eXtractingthe/pin after the fracture has healed'.

ther. objects willi. appear liereirlafter.V

` In carrying out the present invention, the'pin isipreferably constructed of aV rod. having sufcient' resiliency to adapt itself to the channel of` the canal and to realign i't'seilf WithinV the lione. antifl curved. to a more or less dgreegvwithkti'ie i outer'ztac'e of" the curved endY presentlng.` a sled- 'The forward end of the pin is pointed,

runnershaped surface whichv strikes the inner surface of the cortex and glides along' the' same thereby' preventingn the point froin'engaging' and penetrating' the cortex when thev pin isY properly ,driven into the bone with blows` of; a ina-liet.v

'The' opposite end Vofthe rod'iis Bentupon itto which the pointed 'end` is bent, and engages the outside of the cortex when the pin is driven into place thereby preventing the pin from inigr'atinginto the` medullary cavity ortwisting while in use'. When the pin is inserted in the corne; the. hool'edend projects a slight distance into the`Y soft tissue and` causes minimal'irritation even in superncial locations; and is' usually well' tolerated by the tissues. therfunctions ofthe hookedxhea'd-will more fully appearhereinafter; i

The invention. will he `incre readilyy understood by reference'v to the accompanying" drawings, formlngfa' part of the specincaztion andl in which: j

Figure i` is a perspective view of a 'rack for holding a plurality' of pins' of graded lengths; and' illustrating several pins supported therein.

Figure 2'is aside elevation of the headed end of'a pin embodying' the invention.

Figure 3 vis a rear' elevation of the saine.

Figures 4, 5" and 6 are front, sideand'reariele- 'va-tions respectively of the forward'y or pointed end of the pin.

Figure-tis an end'view of the pin;

Fiacre 8"'i's a longitudinal sectional" view of" a humerus drilled at' the upp'erend" to admit" a pin: into the inedullary cavity.

Figures 9'; loand l1 are similarA views ofthe hunierus" illustrati'ng successive stages, respectively, in the" process of inserting a pin therein.

Figurel lf2' is' a; longitudinal" sectiona1` 'vew'jof a fractured'feinur'witha flxingipin insertedthereln.

Figure 13" is a similar View of a fractured 1 femurin which the fracture is locatedv toward the` lower end. and illustratingv the usei or two pinsv to maintain' the parts' i'ii-ixedv position.

Figure 14 a detailrsect'ion illustrating' the mannerv of attaching" al 'fractured' condyl-e- 'to the num-crus;

Figure: 15'Y is a longitudinal: section of effractured: claviclel with a" xing pin inserted there- Figure i6 isa diagramy of aV hand4 and'wrist, illustrating' a' fractured" radius 'and afractured 'inetacarpal bone, each with, its` parts held in place by aK pin. Y

Referring to the drawings lll'4 indicates the pin which is 'formed of a round stainless steel rodi; preferably 1'8.l'2` stainless steel; whichcan be purchasedin rods ofsuitable diameters. such rods adapt themselves well to fastiilinillg'",A 'and when hardened, have-sufficient strength forY the purpose' intended? and` also' are" corrosion resistant and yinon'sniaenetic; v i

A ticular case.

However the invention is not limited to the use of any particular metal, alloy, or o-ther material, provided it is corrosion resistant, and has suicient strength and resiliency to meet the necessary requirements.

The rod I is slightly bent near one end, as at II, and then bent fupon iftself forming a hooked or U-shaped head I2 which is offset from the axis of the pin and adapted to receive the blows of a mallet. The end I3 of the U-shaped head is rounded and smoothed as by grinding and terminates in a tip I4 which is preferably obtusely sharpened.

The forward or opposite end I5 of the rod from the head I2 is slightly bent or curved toward the same side as said head, and the outer curve thereof is ground to form a sled-runner shaped face I6. Upon each side of said face I6, the end I5 is ground obliquely backwardly, as at Il, fcrming a tapered point I8 to afford better penetration.

While only a slight curve or bend to the forward end of thepin is preferably provided when .the pins are formed, the surgeon may -vary the curvature of the point as indicated by the par- When the pin may be inserted at the end of a bone or at only a slight angle to the axis of the bone, the normal slight curvature is sufficient; but the more oblique the entry must be made to the axis of the bone, the greater the o curvature that must be given the pointed end in order that the face I6 shall engage and ride upon the cortex instead of the point I8. This extra curvature may be given to the point by the surgeon iny the operating room after the angle of entry has been'determined.

Since the use of the pin may be adapted to most of the long bones of the body, it becomes necessary for the surgeon to have available a large assortment of pins, varying both in diameter and in length. In practice it is desirableito furnish the pin in setsof 4/16" diameter which are used for the femur; 3/1 s diameter for the humerus and tibia, 2/16 for the radius, ulna andl fibula, and smaller ones for the clavicle, metacarpaland other small bones.

vIt can be determined in advance of an operartion the suitable diameter of pin to be used for la given bone, but the lengthy thereof must be carefully chosen for the individual patient.

of inches.. It is also well to provide a separate Y rack for each diameter'of pin and so arranged as It is therefore necessary to provide the pins of each diameter, in setsvarying in lengths by fractions 'gage the contex b and be deflected downwardly,

thereby preventing the, tip of the point I8 from entering or perforating the cortex. 'Ilhe face I6 follows down the surface of the cortex and thus serves to guide fthe pin. As the cavities of bones vary somewhat it is not unusual to see the pin rotate somewhat as it is driven down the shaft; and it sometimes becomes necessary to rotate the pin manually into its proper relation. It is obvious that this may be readily done by means of the hooked head I2. The pin is driven downward to a point just above the olecranon fossa, a pin of the proper length having been selected; and the point I4 of the head engages the bone and holds the pin firmly against any tendency to twist.

Figure 12 illustrates a femur f fixed with a pin I0. When the fracture of the femuris in the upper two-thirds of the shaft, as indicated in this figure, the pin is introduced through the superior portion of the great trochanter g, and driven downwardly to the supraco-ndylar region. When the fracture occurs in the lower third of the shaft of the femur, the medullary canal is so spacious that a good fixation is best had by introducing a pin through the medial epicondyle h and driving f' the pin upwardly as illustrated in Figure 13. In

such cases the use of two pins, as shown, is usually indicated.

Figure 14 illustrates the manner-of attaching a fractured condyle z' to the humerus at the elbow. y In Figure 15, i indicates a fractured clavicle in which the pin I0 is inserted through an oblique drill hole e in the cortex.

In Figure 16,v lc indicates a fractured metacarpal bone with a small pin I0 inserted therein and l indicates a fractured radius with the pin I0 therein.

It should be noted that in every use of the fixing pins, only the rounded head I2 extends into the soft tissues adjacent the bone, and this is not likely to cause irritation even in supercial locations.

When the pin has served its purpose it may be ings is convenient. As shown herein, the rack comprises a Yplate'ZI from which extend upper land lower flanges 22 and 23 respectively each provided with a number of perforations 24 to receive vthe pins I0 as illustrated; .the hooks I2 resting upon the upper flange I2 and thereby supporting the pins in the rack. Preferably, the indicia 25 are provided adjacent the position provided for each pin of a given length, so that they maybe readily selected. It is also obvious that f f with a rack of the type disclosed, the full set of pins may be readily sterilized without. removal from the-rack.

In Figures 8 to 11 inclusive, isv illustrated theV method of inserting the fixing 'p'in I0 in a fraciturd humerus. The shaft a of the humerus includes the cortex b, and the medullary'cavity c pin. may be palpated through the skin and the pin removed through a smallincision under local analgesia. To remove the pin after the head I2 has been exposed, it is necessary only to engage the tip of a screw driver within the hooked head .and tap the same with a mallet. Y

It should also be understood, in connection with the mounting and removal of my improved the will ofthe surgeon.

fracturefixing pins that the hooked end thereof may, when desired, be bent at a right angle to the point, or in fact in other selected directions accordingtothe particular place of insertion and When using fixing pins as above described vit is rarely necessary to supplement them with casts, external splints or other apparatus, so

that the injured member is not immobilized, and the patient is more quickly able to usethe injured part. -Also it has been. found Vthat the healing of the fractured bone is more rapidthan when immobilized.

It is believed the herein' disclosed fracture'xing pin is the only one which utilizes the spring principle of three-point pressure, utilizing the resiliency inherent in the pin and the natural pull of the muscles in the extremity. For example, in the fixation of a fracture of the femur, as illustrated in Figure 12, the strong pull of the adductor muscles which will be recognized as upward and to the left from the lower end portion of the femur toward the pelvis with which the femur would be connected give the fractured femur a tendency to bow in an antero-lateral direction or toward the left as viewed in Figure 12. The xing pin, being curved as indicated in Figure l2 utilizes this muscle pull by its tendency to bow medially, resulting in three-point pressure, centrally and at each end, resulting in more secure fixation without the necessity of impacting the marrow cavity. This same principle, while varying with the muscle pull in various parts of the body, is an important factor in secure fixation of many of the long bones, particularly with reference to preventing rotation.

It is to be understood that the herein disclosed pin does not fill the medullary canal, thereby allowing the bone to be free to glide upon the pin, so that the ends of the bones are in constant contact, allowing the normal muscle pull of the extremity to continuously compress the bone ends to stimulate osteogenesis or bone healing.

Again with reference to the benefits of the resiliency inherent in the disclosed fracture fixing pins attention is directed to Figure 14 wherein the fracture of a humerus condyle is shown. In a fracture of a condyle or bony prominence near a joint, the tendency of the fragment is to displace laterally, or to the right as viewed in Figure 14. By bending the pin slightly near its point and leaving the head or hook end straight, the pin will travel in an arc through the cancellous bone until its arc attened end portion strikes the cortex of the shaft. This causes the pin to continue travelling in an arc, and as the straight head end part of the pin is forced to travel this same arc it results in a spring force which compresses the broken fragment toward the left or toward the midline.

While one form of the invention has been shown for purposes of illustration, it is to be clearly understood that various changes in the details of construction and arrangement of parts may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A fracture fixing pin comprising a flexible rod of generally circular cross section having a smooth exterior and a pointed entry end, and a curved guiding face at one side adjacent said pointed end and so placed with relation to the point as to be engageable with the Acortex at the side remotefrom the point of entry of the pin when driven into a medullary canal at an angle to the axis of the canal and act to defiect said point in a manner for preventing pene-,

tration of said cortex by said point.

2. A fracture fixing pin as defined in claim 1 in which the pointed end is longitudinally curved slightly and the outer arc of said pointed end curve bears the guiding face, said face being approximately fiat in transverse section andi tapered at opposite side edges of the point.

6 3. A fracture fixing pin as defined in claim 1 in which the pointed end is longitudinally curved slightly and the outer arc of said pointed end curve bears the guiding face, said face being approximately fiat in transverse section and tapered at opposite side edges to the point, and

said end being acutely bevelled transversely of the rod at said side edges and merging into said point.

4. A fracture fixing pin as defined in claim 1 in which the rod end remote from the point terminates in a hook bending away from the side remote from the side having the curved guiding face, said hook merging smoothly with the main body of the rod at its full cross section and gradually reducing in cross section into a point disposed for engagement in bone adjacent the point of entry of the pin in a manner tending to secure the pin against migration.

5. A fracture fixing pin comprising a rod` smooth of external surface and round in cross section and having a pointed entry end with the point disposed to one side of the axis of the rod, and a single fiat guiding face merging into said point from the opposite side of the rod, and having at its other end a retraction facilitating hook portion bearing a predetermined definite relation to said fiat guiding face, said pin while being pliable to an extent for permitting preset shapingprior to insertion and during driving also having inherent resiliency effective to cause it constantly to tend to return to its present shape during its active positioning in a fractured bone structure.

6. A fracture fixing pin comprising a longitudinal rod smooth of external surface and generally round in cross section along its main body and having an entry end presenting a single relatively flat guide surface adapted to facilitate travel along a medullary canal and transversing the axis of the main body at an angle across the full width of said main body and having at its other end a driving and retraction facilitating head offset in a predetermined definite direction with relation to said at guide surface and adapted to remain close outside of and close against a bone as a migration stop and bent back upon itself in the direction of the length of the main body of the rod and shaped to present a well rounded smooth surface which minimizes irritation of overlying tissues and which starts at the full cross section of the main body at its juncture with said main body and gradually merges into a terminal point.

LESLIE V. RUSH.

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Number Country Date 235,382 Switzerland c Apr. 3, 1945 908,558 France Oct. 1, 1945 OTHER REFERENCES Journal of Bone & Joint Surgery for April, 1946. page 313.

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