Veterinary Surgical Tool For Enlarging The Pelvic Girdle Of A Heifer During Parturition

Abstract

A veterinary tool facilitating sectioning of the pelvic floor of a heifer to remedy dystacia in parturition of a heifer comprises an elongated shank having a hook-shaped section at a forward end and an abutment flange at a rearward end. A slidably impact weight is mounted to the shaft forward of the abutment flange. The hook-shaped section includes a rearwardly facing, angularly projecting knife edge and a forwardly projecting blunt point. A portion of the shank is polygonal in cross-section and extends through a complementary opening within the impact weight. This relationship provides for longitudinal movement of the impact weight along the shank but prevents angular movement of the shank and weight relative to one another facilitating manual angular alignment of the knife edge by turning the weight about the shank axis. The impact weight may be forcibly moved longitudinally along the shank to strike the abutment flange creating a reaction force sufficient to pull the knife edge rearwardly to section the pelvic floor of the heifer and thereby allowing enlargement of the transverse diameter of the pelvic girdle.

Description

BACKGROUND OF THE INVENTION

The present invention relates basically to the field of veterinary surgical tools for use in assisting parturition in cattle and more particularly to such tools utilized for sectioning the pelvic floor to allow the pelvic girdle to be enlarged transversely.

Although normal parturition without complications in mature cattle is common, dystocia or difficult birth is more frequent among younger heifers. Further, larger calves are being produced due to improved breeding techniques such as artificial insemination. The difficult delivery must be effected either by way of Caesarean section or by enlarging the pelvic girdle. Obviously, the Caesarean section involves a certain degree of danger to the dam as well as expense to the rancher since he must utilize the services of a veterinarian.

The other method of enlarging the pelvic girdle commonly involves the severing of the pelvic floor by use of an ordinary hammer and chisel. A veterinarian usually inserts the chisel along the vaginal tract of the dam, positioning it with the edge against the ischium, which is the anterior bone of the pelvic floor. As assistant, usually the rancher, then pounds the sharp edge of the chisel through the pelvic floor to separate the lateral sides of the pelvic girdle to thereby enable the pelvic girdle to be enlarged transversely and allow passage of the calf therethrough. Obviously the use of the hammer and chisel presents several difficulties, the first being discomfort to the dam. Further, inaccurate positioning of the chisel against the pelvic floor can result in damage to the nervous system of the dam by accidently severing nerves adjacent the area. For these reasons such a technique is seldom used.

It is therefore a first object of my invention to provide a surgical tool for effecting a sagittal section of the pelvic floor without danger of unnecessarily wounding the dam or fetus.

Another object is to provide such a surgical tool that can be operated by one man.

An additional object is to provide such a surgical tool that includes a blunted point which, upon insertion, pushes tissues aside rather than cuts through, thereby decreasing danger of infection due to damaged tissues.

A further object of my invention is to provide such a tool which will quickly and relatively painlessly section the pubic floor to facilitate transverse enlargement of the pelvic girdle.

Another object is to provide such a tool that is simple in construction and easy to manufacture.

These and other objects and advantages will become apparent upon reading the following description, which taken with the accompanying drawings describe a preferred form of my invention.

A BRIEF DESCRIPTION OF THE DRAWINGS

A preferred form of the invention is illustrated in the accompanying drawings in which:

FIG. 1 is an isometric view of the tool;

FIG. 2 is a cross sectional view taken along line 2--2 in FIG. 1;

FIG. 3 is a sectioned view taken along line 3--3 in FIG. 1;

FIG. 4 is a bottom plan view of the forward end of the tool;

FIG. 5 is an elevational view of the forward end as seen from the top in FIG. 4;

FIG. 6 is a view of the pelvic bones of a heifer as seen from the front and somewhat from below;

FIG. 7 is a lateral sectional view of the pelvic bones shown in FIG. 6 illustrating the operation of the tool; and

FIG. 8 is a schematic operational view of the tool illustrating a lateral anterior section through a heifer during parturition.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The apparatus of the present invention is illustrated in the accompanying drawings as generally designated by the reference numeral 10. The tool comprises an elongated shank 11 having a forward end 12 and a rearward end 13. The forward end of the shank includes a hook shaped section 14. Section 14, as shown in FIGS. 4 and 5, includes a forwardly projecting point 17 and a rearwardly-facing knife edge 18. The knife edge 18 extends radially outward and rearward from the forward end 12 at an acute angle to the shank 11. The knife edge 18 extends outwardly a predetermined distance which will be discussed in greater detail below.

The rearward end 13 includes a radially projecting abutment flange 23 rigidly fixed to the shank 11. The abutment flange 23 is operatively associated with an impact means 26 which generally comprises a longitudinally slidable weight 27 mounted to the shank 11. As shown in FIG. 2, the weight 27 includes a polygonal axial opening 31 extending longitudinally therethrough and slidably receiving a complementary polygonal periphery 32 of the shank 11. The complementary shapes of the opening 31 and the cross sectional periphery 32 of the shank 11 defines an aligning means 28 which is utilized to provide accurate control of the angular position of the knife edge about a longitudinal axis passing through the shank 11. This feature is evident in FIG. 2 wherein the opening 31 is illustrated as being slightly larger than the polygonal cross section 32 of the shank 11. Such a relationship allows free longitudinal movement of the shank and weight relative to one another but prevents relative angular rotation of the shank and weight about the longitudinal axis of the shank. Therefore, by turning the weight 27 about the longitudinal axis, the shank and knife edge will be turned accordingly.

Referring now to FIGS. 6 and 7, the pelvic bones of a heifer are illustrated in detail. The pelvis is generally designated by the reference numeral 33 and comprises a series of bones forming a longitudinal opening or pelvic girdle 36. The bones forming the pelvic girdle are the ilium 37, the ischium 41, and the pubis 42. The three bones unite at the acetabulum 38 to form the socket for the hip joint. The pubis 42 and ischium 41 are firmly joined together along the symphysis pubis 43 to form the pelvic floor 47. The ischium 41 and pubis 42 also define the obturator foramen 46 through which various arteries and nerves pass into the hind legs of the heifer.

The most desirable location to effect a section through the pelvic floor is along the symphysis pubis or closely adjacent thereto. This location is desirable since various arteries and nerves pass through the obturator foramen on either lateral side of the symphysis pubis.

Insertion and relative positioning of the forward end 12 of the tool 10 is illustrated in FIG. 8 to effect a sagittal resection closely adjacent the symphysis pubis 43. Insertion of the tool 10 is initiated through the soft tissues of the vulva 51 where, because of the external position, the puncture wound will heal rather quickly. After insertion through the vulva 51, the tool is directed forwardly with the vagina 52 and urethra 56 on the dorsal side of the shank, and the dorsal side 53 of the pelvic floor 47 on the ventral side of the shank 11. The knife edge 18 is held substantially horizontally as the forward end 12 is inserted over the pelvic floor 47.

The blunt point 17 and a corresponding forwardly facing dull edge 20 of the knife edge 18 are important features of the present invention in that they serve to push surrounding tissue aside rather than cut, thereby greatly reducing any chance of damaging any surrounding tissues, especially that of the urethra 56 and urinary bladder 57.

Once the forward end 12 has reached the point adjacent the anterior side of the pubis 42, the blunt point 17 serves to push the bladder 57 slightly forwardly. The knife edge may then be rotated downwardly and aligned with the symphysis pubis by turning the weight 27 about the longitudinal axis of the shank 11. When the knife edge reaches the desired angle, the user holds the knife edge in that particular angular orientation simply by holding the weight 27 angularly stationary about the longitudinal axis of the shank 11. He then moves the weight 27 quickly and forcefully from a position toward the front end 12 of the shank 11 rearwardly toward the abutment flange 23.

A substantial reaction force is created as the weight 27 strikes the abutment surface 23. The force has a rearward direction coaxial with the longitudinal axis of the shaft 11 and is sufficient to pull the knife edge 18 rearwardly through the pelvic floor 47 to quickly and evenly section the ischium 41 and pubis 42 along a sagittal plane through or closely adjacent the symphysis pubis 43.

As noted in the drawings, the knife edge 18 extends outwardly from the shaft 11 a distance substantially equal to the vertical thickness of the pelvic floor 47. This feature is very important in that during the sectioning operation, the knife edge 18 is positioned so that it is drawn only through the bones forming the pelvic floor 47. The shaft section rearwardly adjacent the knife edge is also important during this operation in that it slides over the dorsal side 53 of the pelvic floor 47 to prevent the knife edge 18 from moving downwardly past the ventral side 50 as it passes through the pelvic floor 47.

The primary advantage of the present invention over the prior use of a hammer and chisel is that the section is completed in an outward movement of the knife edge 18 with virtually no possibility of injuring the fetus, where the process utilizing a hammer and chisel involves severing the pelvic floor inwardly from a posterior position. Once the chisel has passed through the bone, it is a distinct possibility that it could continue forwardly with sufficient force to pierce the urinary bladder 57 and wound the fetus 58.

It may become obvious from the above description and attached drawings that various changes and modifications may be made therein without departing from the scope of this invention. Therefore, only the following claims are intended to define this invention.

Claims

What I claim is:

1. A veterinary surgical tool for performing a sagittal section through the pelvic floor of a heifer to allow enlargement of the pelvic girdle during parturition, comprising:

an elongated shank having a sufficient length between a forward end and a rearward end to allow insertion of the forward end through the pelvic girdle with the rearward end extending rearwardly clear of the heifer;

a hook-shaped section of the shank located at the forward end having a rearwardly facing surface formed thereon for engaging an anterior portion of the pelvic floor along a sagittal plane;

a knife edge formed along the rearwardly facing surface protruding radially outwardly from the shank a distance substantially equal to the vertical thickness of the pelvic floor;

an abutment flange fixed to the shank adjacent the rearward end;

impact means operatively connected to the shank for manual longitudinal movement along a longitudinal shank axis and for forcible impaction against the abutment flange to create a reaction force against the shank directed rearwardly along the shank axis sufficient to draw the knife edge rearwardly through the pelvic floor, thereby effecting a sagittal section of the pelvic floor and allowing enlargement of the pelvic girdle; and

aligning means operatively interconnecting the shank and the impact means for maintaining the impact means and shank in angular alignment with each other to enable an operator to manipulate the knife edge angularly about the longitudinal shank axis by angularly rotating the impact means about the longitudinal shank axis, and to maintain the knife edge in a fixed angular orientation when the impact means is held angularly stationary thereby enabling the operator to accurately position the knife edge against the pelvic floor and to hold that position during the sectioning operation.

2. The tool set out in claim 1 wherein the impact means comprise an elongated weight slidably mounted to the shank forward of the abutment flange, and wherein the aligning means comprises a continuous polygonal shank periphery formed along the shank and extending through a complementary polygonal opening formed longitudinally through the weight, the polygonal opening of the weight being of sufficient size to prevent the shank and weight from rotating angularly relative to each other about the longitudinal shank axis.

3. The tool set out in claim 1 wherein the knife edge forms an acute angle with a portion of the longitudinal shank axis extending rearwardly from the forward end.

4. the tool set out in claim 1 wherein the hook-shaped section includes a forwardly blunt projecting point for pushing tissues aside without cutting or puncturing the urethra and urinary bladder as the forward end is inserted and directed along the pelvic floor.