US3008467A - Kidney stone extracting machine - Google Patents

Description

Nov- 14, 1961 w. MORRIS 3,008,467

KIDNEY STONE EXTRACTING MACHINE Filed Sept. 50, 1957 2 Sheets-Sheet 1 Nov. 14, 1961 w, MORRIS KIDNEY STONE EXTRACTING MACHINE 2 Sheets-Sheet 2 Filed Sept. 30, 1957 NVENTOR. ZQMEA/arwis BY WM v United States Patent Office 3,008,467 KIDNEY STONE EXTRACTING MACIIINE William E. Morris, 408A N. Meridian, North Chicago, Ill. Filed Sept. 30, 1957, Ser. No. 686,931 6 Claims. (Cl. 128-328) The present invention relates to a device for extracting kidney stones from the ureter or duct extending between the kidney and the bladder, although some aspects of the present invention may have a broader application.

Numerous devices have been heretofore developed for removing kidney stones from the ureter. Most of these devices comprised a long flexible tube adapted to be inserted up into the bladder and then through the ureteral meatus or opening therein communicating with the ureter. Associated with the end of the flexible tube was a stonecatching basket usually comprised of a number of spaced longitudinal filaments made of plastic or metal, which were joined together at the far end thereof to form a pocket for catching kidney stones. Some of these prior devices include a basket expanding and contracting means comprising a wire extending to the outer end of the basket for elfecting the expansion and contraction of the basket filaments or wires. The use of this basket expanding means often interfered with the movement of the kidney stone into a position to be caught in the pocket of the basket.

In one form of expanding kidney stone extractor, the expansion of the filaments or wires forming the basket was unsymmetrical resulting in a distorted shape where.

the axis of the basket was out of alignment with the axis of the flexible tube, thereby making it 'difiicult to pull the basket through the ureter in its expanded state.

In another type of expanding kidney stone extractor, the expansion, although symmetrical, extended in three or more directions which had certain disadvantages which will become apparent as this description proceeds.

Each of these prior types of devices was used with varying degrees of success. In the repeated attempts by the doctor to catch the stone, the ureter was often severely irritated to the great harm and discomfort of the patient.

The primary object of the present invention is to provide a kidney stone extracting device which is substantially more effective than prior kidney stone extracting devices.

Another object of the present invention is to provide a kidney stone extracting device of the type having filaments or wires forming a basket which is expandable in a unique manner so that the ureter expands in a way that causes the Walls thereof to exert an inward pressure which forcesthe kidney stone into the basket where it may be readily caught by the pocket therein upon removal of the device from the ureter.

Still another one of the objects of the present invention is to provide a kidney stone extracting device having an expandable and collapsible basket where novel basket expanding and contracting means is provided which does not obstruct the space within the basket as in prior devices.

Still another one of the objects of the present invention is to provide a kidney stone extracting device wherein the filaments or wires making up the basket thereof are made of stainless steel arranged so that the danger of breakage and consequent piercing of the ureter thereby, which was a danger in prior metal wire type extractors, is avoided.

An overall object of the present invention is to provide a kidney stone extracting device of the type above described which is reliable in operation, rugged and relatively inexpens ve to construct.

One of the important aspects of the present invention is the provision of a stone-catching basket formed by Patented Nov. 14, 1961 only two arms which are movable by manipulation of a handle at one end of the flexible tube from a collapsed position, where the basket occupies a relatively small space, to an expanded position where both arms occupy respective positions symmetrical with respect to the longitudinal axis of the device. The arms are made sufficiently rigid that they expand the walls of the ureter into an elongated oval shape where the elongated walls thereof provide an inward pressure which forces the kidney stone into the space between the arms where it can be caught in the basket upon removal of the expanded basket from the 7 of the kidney stone catchin ortion of the device shown' ureter. This action is not readily possible where the filaments or wires making up the basket expand in three or more directions and wherein they have insulficient rigidity and are separated an insufiicient amount to ex pand the walls of the ureter.

Additionally, the basket-forming arms are each designed to provide a limited longitudinal recess into which the kidney stone may be snared and then guided into the pocket of the basket. In its most preferred form, the recess is formed bya pair of relatively closely spaced filaments or wires which occupy similar positions with respect to the longitudinal axis of the device, so that they respectively confront the corresponding filaments or wires of the opposing basket-forming arm. It has been found that thin stainless steel wire cables can be used for the latter recess-forming wires or filaments without the danger ofbreakage which causes piercing of ureter walls.

In accordance with another aspect of the present invention, the means for expanding the opposed basket-forming arms include a spreader member which has lateral camming shoulders which engage the inner surfaces of the inner ends of the opposed basket-forming arms and cam the arms apart. Preferably, the inner ends of these arms are formed by rigid stainless steel shank members joined at their outer ends to said closely spaced stainless steel wire cables.

A metal sleeve is provided into which said stainless steel shank members may be retracted for holding the basket in its collapsed position. Said spreader member projects from the outer end of the sleeve and when said shankrmembers are retracted into said sleeve the closely spaced apart wire cables straddle the spreader member. By means of a rod extending the length of the above mentioned flexible tube and connected to the inner ends of the arm shanks, the latter can be pushed out of the above mentioned sleeve and against said camming shoulders which spread the arm shanks and the closely spaced wire cables apart a suflicient distance to expand the ureter walls. Since only two arms are involved and the arm shanks are relatively rigid, the arms can expand the walls of the ureter into an elongated oval shape to accomplish the advantages above described.

The above mentioned construction of the novel kidney stone extracting device of the invention provides an extremely rugged, and reliable stone extracting device.

Other objects, advantages and features of the invention will become apparent upon making reference to the specification to follow, the claims and the drawings. wherein:

FIG. 1 is a sectional view of the human bladder, kidney, and ureter connecting the bladder and the kidney, with the kidney stone extracting device of the present invention inserted up into the ureter in preparation for the removal of a kidney stone lodged in a constricted lower section of the ureter;

FIG. 2 is an enlarged view of the kidney stone extracting device shown in FIG. 1, with the kidney stone-catching portion thereof in its collapsed or contracted position; 1

FIG. 3 is a greatly enlarged longitudinal sectional view 3 in FIG. 2, the solid lines showing the basket thereof in a collapsed state and the dotted line showing the basket in an expanded state;

FIG. 4 is a transverse sectional View taken along section line 4-4 in FIG. 3;

FIG. 5 is a transverse sectional view taken along section line 5-5 in FIG. 3;

FIG. 6 is a perspective view of the kidney stone catching portion of the device shown in FIG. 2 in its expanded state;

' FIG. 7 is a longitudinal sectional view through the bottom portion of the ureter in which a kidney stone has lodged, showing the kidney stone extracting device of the present invention being pushed past the stone;

FIG. 8 is a transverse sectional view of the ureter and the kidney stone extracting device the-rein, taken along section line 8-8 in FIG. 7;

FIG. 9 is a view corresponding to FIG. 7 showing the kidney stone catching portion of the device of the invention in its expanded position opposite the kidney stone in the ureter;

FIG. 10 is a transverse section through the ureter and the kidney stone extracting device, taken along section line 10-10 in FIG. 9; and

FIG. 11 is a perspective view of the kidney stone catching portion of the device with the kidney stone caught in the pocket thereof as the latter is being removed from the ureter.

Referring now more particularly to FIG. 1, the kidney is there identified by reference numeral 2, and a duct 4, commonly referred to as a ureter 4, extends from the kidney 2 to the bladder 6. Communication between the ureter and the bladder is through an opening 8 in the wall of the bladder, which opening is commonly referred to as a ureteral meatus. The ureter is generally constricted near the lower end thereof, as at point 4', and kidney stones, like stone 5, of a size and shape to become lodged in the ureter usually pass from the kidney and lodge in this constricted portion 4'. The kidney stone extracting device of the present invention is generally indicated by reference numeral 10 and consists generally of an elongated flexible tube 12 of a construction commonly found in kidney stone extractors heretofore made, an operating rod or wire 14 (-FIG. 2) which passes through the elongated tube 12, kidney stone catching means generally indicated by reference numeral 16 attached to one end of the rod 14 and located at one end of the tube 12, and manual operating means generally indicated by reference numeral 18 for moving rod 14 longitudinally within the tube 12, so as to manipulate the stone extracting means 16 in a manner to be explained. A tapered tip 19 extends from the end of the stone catching means 16 which tip, by means of well known cystoscopic apparatus, is inserted into the ureter through the ureteral meatus. Now that the basic parts of the device have been outlined, some of the structural details thereof will be given.

In accordance with the present invention, the stone extracting means 16 comprises two identical longitudinal arm assemblies 20-20 which are in opposed relation. As will be explained, the arms 20-20 are movable between contiguous positions (FIGS. 2 and 3), where the space occupied thereby is in the order of the space occupied by the flexible tube 12, and an expanded position (FIG. 6) where the two arms preferably bow outwardly in a symmetrical manner relative to the longitudinal axis of the device and form what may be referred to as a stone catching basket. Each of the arms 20 has a shank portion 22 preferably formed of a stainless steel rod having a semi-cylindrical side 24 (FIG. 5) and a flat side 26 extending between the ends of the cylindrical side 24. A hemispherical recess 28 is formed in the fiat side 26 of the bottom end of each shank 22 and a semi-cylindrical channel 30 extends from the base of the hemispherical recess 28 to the adjacent end of the shank 22. The shanks of the two arms 20-20 are positioned with the flat sides 26 thereof in face to face contact and with the hemispherical recesses 28-28 and channels 30-30 in confronting relation to form together a spherical recess and a cylindrical channel. The end of the operating rod 14 has a spherical enlargement 32 on the end thereof which fits into the above mentioned spherical recess with the rod 14 passing through the above mentioned cylindrical channel.

The two shanks 22-22 are held together around the enlarged end of the rod 14 by a locking collar 34 which has a small opening 36 at one end which closely surrounds the rod 14 and a large opening 38 at the other end which surrounds the bottom of the shanks 22-22. The collar 34 may be soldered or otherwise fixedly secured to the shanks 22-22.

The upper ends of the shanks 22 are enlarged to form generally wide, flat heads 40-40 each having a pair of longitudinal holes 42-42 drilled therein. Anchored in the holes 42-42 in each of the heads 40-40 are a pair of spaced elongated longitudinally extending stone catching filaments 44 or wires, preferably stainless steel wire cables instead of solid steel wires or the like, although the broader aspects of the invention contemplate the use of solid metal or even plastic wires or filaments. The cables, for example, may comprise about A; inch length strands (e.g. 6 strands) of twisted .004 in. diameter steel wire. The steel wire cables are secured in place within the holes 42-42 preferably by lead solder. The use of higher melting point solders is less desirable because the high temperatures required in such soldering affect the temper of the stainless steel and thereby lessen the durability and strength thereof.

The outer ends of the steel wire cables 44-44 are brought together around the depending shank portion of a metal connector 4-6 and are anchored thereto by lead solder. A stone catching pocket 47 is thereby formed at the outer ends of the arms 20-20 into which kidney stones are directed in a manner to be explained. The connector 46 has a threaded extension 48 around which is threaded an internally threaded socket 49 at the base of the tapered tip 19, which may be made of a suitable plastic material, such as polyethylene or the like.

As previously indicated, the arms 20-20 are movable from a collapsed to an expanded condition. The collapsed condition of the arms is maintained by means of cylindrical metal sleeve 50 suitably secured around the end of the flexible tube 12. By means of movement imparted to the operating rod 14, the shanks 22-22 of the arms 20-20 may be drawn completely within the metal sleeve 50. To this end, the outer dimensions of the contiguous shanks 22-22 are slightly less than the corresponding internal dimensions of the sleeve 50.

The expansion of the arms 20-20 may be effected in a number of ways, the most preferred way being by means of a spreader head 53. The spreader head 53 is joined to the top of the sleeve 50 by metal extensions 55-55 which may be cut from the blank from which the sleeve 50 is formed. The head 53 may be formed by applying lead solder between the metal extensions. The spreader head 53 has a pair of lateral camming shoulders 57-57 which are in the path of movement of the flat sides 26-26 of the arm shanks out of the sleeve 50. The arm shanks 22-22 are moved out of the sleeve 50 by means of the operating rod 14 in a manner to be explained.

When so moved, the camming shoulders 57-57 cam apart the ends of the arm shanks so that the arms have the longitudinally symmetrical, outwardly bowed shape shown in FIG. 6. In this expanded position, a relatively large unobstructed space generally indicated by reference numeral 60 is provided between the intermediate and upper portions of the arms 20-20, so that a kidney stone may be readily caught within the con-fines of the arms 20-20. The arms 20-20 in their expanded positions are spaced apart in the neighborhood of three or more times the diameter of the sleeve 50 or the flexible tube 12.

When the arm shanks are retracted within the sleeve 50, the camming shoulders 57-57 are straddled by the respective pairs of spaced steel wire cables 44. In the collapsed position of the arms 20-20, the overall dimen sions of the space occupied thereby are in the neighborhood of the dimensions of the space occupied by the sleeve 50 of the flexible tube 1'2. The maximum width of the spreader head 53 is also in the neighborhood of the diameter of the sleeve '50. The latter may, in turn, be slightly smaller than the internal dimensions of the constricted portion 4 of the duct. The latter is usually in the neighborhood of 3 mm., and the diameter of the sleeve 50 may be about 2 to 3 mm.

The manual operating means 18 for imparting longitudinal movement to the operating rod 14 may comprise any one of a number of well known types of operating means for moving a rod 14 longitudinally of an elongated tube through which the rod passes. In the example illustrated, the manual operating means 18 comprises a bifurcated stainless steel member 62 whose arms 63-63 are slidably disposed in correspondingly shaped offcentered holes 64-64 of the cylindrical body portion of a slide piece 65. The slide piece 65 has a central cylindrical hole 66 adapted to receive the cylindrically shaped enlarged end 67 of the operating rod 14. The enlarged end 67 may be locked within the hole 66 by a locking screw 69 laterally threading through the cylindrical body portion of the slide piece 65. The base of the bifurcated member 62 has a longitudinal bore 71 which receives the cylindrical end 73 of the flexible tube 12, and the latter may be locked in place within the bore 71 by a locking screw 75 laterally threading through the base of the member 62.

The ends of the arms 63-63 of the member 62 are mounted within complementary recesses in an end cap 80 having a thumb-receiving ring 82 secured to the end thereof. Cooperating finger-receiving rings 85-85 extend from opposite sides of the body of the slide piece 65. The operating rod 14 may thus be moved longitudinally within the flexible tube 12 by inserting the thumb into the thumb ring 82 and any other two fingers of the same hand into the rings 85-85 and then pulling or pushing the finger rings 85-8-5 relative to the thumb ring 82.

The manner in which the device of the present invention is used is as follows: After tape-red tip 19 has been extended into the ure-teral meatus 8 using a cystoscope, the tip 19 is pushed into a position so that it is well up into the ureter and perhaps even into the kidney 2, (FIG. 1) while the arms 20-20 are in their collapsed position brought about by pulling the finger rings 85-85 toward the thumb ring 82. Due to the inherent flexibility of the walls of the ureter, sleeve 50 and the flexible tube 12 may be pushed by the stone lodged in the constricted portion 4 of the ureter, as shown in FIGS. 7 and 8. When the stone catching arms 20-20 have been inserted into a position near the top of the ureter 4, the manual operating means 18 is then operated by pushing the finger rings 85-85 away from the thumb ring 82, so as to expand the arms 20-20. The device is then slowly withdrawn from the ureter While the arms 20-20 are in their expanded condition. Since the kidney stones usually lodge in the lower half of the ureter, and most usually in the constricted portion 4, the operator is fairly certain that the expanded arms 20-20 are above the stone upon the initial withdrawal of the device from the ureter. When the spread-apart arms 20-20 are pulled into the narrow or constricted portion of the ureter, the walls of the ureter are expanded into an oval shape, as shown in PEG. 10. This stretching of the ureter walls creates an inward pressure applied by the then long sides of the ureter walls which forces the kidney stone into the space 60 between the arms 20-20. Since the space between the intermediate and upper portions of the arms 20-20 is unobstructed by any control wire or the like, the stone may readily pass in the space immediately between the arms 20-20, aided by the inward pressure exerted by the ureter walls. Each pair of spaced apart stainless steel cables 44-44 provide respective slots 86-86 (FIGS. 6 and 11) through which the sides of the kidney stone may extend when the stone nears the pocket 47. Upon further withdrawal of the device, the stone is readily caught in the pocket 47. The stone moves into the pocket 47 of the basket defined by the cables 44 as the device is further withdrawn from the ureter. The arms 20-20 are maintained in their position as the device is completely withdrawn from the ureter (FIG. 11). The arms there-by help to expand the ureter walls, particularly those walls surrounding the ureteral meatus, so that the latter is not readily damaged by the withdrawal of the stone therethrough.

The instrument is so designed that the danger heretofore present from the use of solid stainless steel Wires due to the breakage of such wires and the consequent piercing of the ureter walls is obviated by the use of stainless steel wire cables 44-44. The novel symmetrical expansion of the arms 20-20 is also an important factor since this results in the stretching of the ureter walls into the oval shape to create the above mentioned inward pressure which forces the stone into the unobstructed space between the arms 20-20. The use of only two arms instead of three or four arms is important in obtaining the oval shape of the ureter walls. The use of a means for positively holding the arms apart further enables the ready stretching of the ureter walls which would not be readily possible if a non-positive spreading action were to be effected. A further factor to insure the catching of the kidney stones is the spaced apart arm sections 44-44 which provide the above mentioned elongated slots for receiving the sides of the kidney stone. Moreover, the device of the invention is extremely rugged, reliable and relatively inexpensive to construct.

It should be understood that numerous modifications may be made of the preferred form of the invention described above without deviating from the broader aspects of the invention. For example, the flexible tube 12 may be shortened for adapting the extracting device for removing stones from the common bile duct.

I claim:

1. A medical instrument for removing stones from a duct comprising: a tube for insertion into said duct, stone catching means at one end of said tube comprising a pair of longitudinal arms, each of which has an essentially rigid longitudinal shank at the inner end thereof and a stone holding section connected to the outer end of said shank and comprising a pair of spaced, confronting, longitudinal, elongated portions connected together at their outer ends, said arms being movable between relatively contiguous positions so as to be readily pushable around a stone lodged in said duct and relatively spaced apart positions where the arms including said respective arm shanks and pairs of spaced elongated portions are bowed outwardly in opposite directions to occupy substantially symmetrical positions relative to the longitudinal axis of said tube, means for holding said arms in contiguous relation, said pairs of spaced confronting elongated stone holding arm portions being thereby held in proximity to one another, and means for moving said arms to said relatively spaced apart positions to form a space therebetween into which a stone lodged in said duct can readily pass.

2. A medical instrument for removing stones from a duet comprising: a tube for insertion into said duct, stone catching means at one end of said tube comprising a pair of longitudinal arms, each of which has an essentially rigid longitudinal shank at the inner end thereof and a stone holding section connected -to the outer end of said shank and comprising a pair of spaced, confronting, longitudinal, elongated portions made of wire cables connected together at their outer ends, said arms being movable between relatively contiguous positions so as to be readily pushable around a stone lodged in said duct and relatively spaced apart positions where the arms including said respective arm shanks and pairs of spaced elongated portions are bowed outwardly in opposite directions to occupy substantially symmetrical positions relative to the longitudinal axis of said tube, means for holding said arms in contiguous relation, said pairs of spaced confronting elongated stone holding arm portions being thereby held in proximity to one another, and means for moving said arms to said relatively spaced apart positions to form a space therebetween into which a stone lodged in said duct can readily pass.

3. A medical instrument for removing stones from a duct comprising: a tube for insertion into said duct, stone catching means at one end of said tube comprising a pair of longitudinal arms, each of which has an essentially rigid longitudinal shank at the inner end thereof and a stone holding section connected to the outer end of said shank and comprising a pair of spaced, confronting, longitudinal, elongated portions connected together at their outer ends, said arms being movable between relatively contiguous positions so as to be readily pushable around a stone lodged in said duct and relatively spaced apart positions where the arms including said respective arm shanks and pairs of spaced elongated portions are bowed outwardly in opposite directions to occupy substantially symmetrical positions relative to the longitudinal axis of said tube, means for holding said arms in contiguous relation comprising a longitudinal sleeve connected to the end of said tube and adapted to envelop said arm shanks, said pairs of spaced confronting elongated stone holding arm portions being thereby held in proximity to one another, and means for moving said arms to said relatively spaced apart positions to form a space therebetween into which a stone lodged in said duct can readily pass, said last-mentioned means comprising a spreader head secured to said sleeve and straddled by said pairs of elongated stone holding arm portions, said spreader head having relatively widely spaced lateral shoulders in the path of movement of said arm shanks out of said sleeve, so as to spread said arm shanks apart, and means for moving said arm shanks out of said sleeve comprising a push rod connected at the inner ends of said arm shanks and passing through said tube, and manually operable means having relatively movable parts secured respectively to the other end of said push rod and to said tube.

4. A medical instrument for removing stones from a duct comprising: a tube for insertion into said duct, stone catching means at one end of said tube comprising a pair of longitudinal arms each of which has an essentially rigid longitudinal shank at the inner end thereof and a stone holding section connected to the outer end of said shank and comprising a pair of spaced, confronting, longitudinal, elongated portions connected together at their outer ends to form a pocket for catching said stones, each of said spaced elongated portions being of substantially smaller cross section than said tube so that when they are in contiguous relation they have an overall cross sectional area similar to said tube, the intermediate portions of said arms including the outer sections of said arm shanks and the inner sections of said pairs of spaced elongated arm portions being movable between contiguous positions so as to be readily pushable around a stone lodged in said duct and relatively spaced apart positions where the arms are bowed outwardly similarly in opposite directions to occupy substantially symmetrical positions relative to the longitudinal axis of said tube, means for holding said arm shanks in contiguous relation comprising a longitudinal sleeve of a size similar to said tube connected to the end of said tube and adapted to envelop said arm shanks, said pairs of spaced confronting elongated stone holding arm portions connected to the ends thereof being thereby held in proximity to one another so as to have a cross sectional area in the neighborhood of the cross sectional area of said tube, and means for moving the upper ends of said arm shanks apart to spread apart said respective pairs of elongated stone holding arm portions to thereby form a space therebetween into which a stone lodged in said duct can readily pass, said last-mentioned means including a spreader head secured to the end of said sleeve and straddled by said pairs of elongated stone holding arm portions, said spreader head having relatively Widely spaced lateral shoulders in the path of movement of said arm shanks out of said sleeve so as to spread the upper sections of said arm shanks apart, and means for moving said arm shanks out of said sleeve comprising a push rod connected at one end to the bottom of said arm shanks and passing through said tube, and manually operable means having relatively movable parts secured respectively to the other end of said push rod and to said tube.

5. A medical instrument for removing stones from a duct comprising a long body for insertion into said duct, stone catching means at the outer end of said body, said stone catching means comprising a first and a second pair of laterally-spaced longitudinal arm portions connected together at their outer ends to form a pocket for catching said stones, the intermediate sections of said respective pairs of longitudinal arm portions being movable between relatively unbo-wed contiguous positions where they occupy a relatively small cross sectional area so as to be readily pushable around a stone lodged in said duct, and relatively spaced apart positions where the longitudinal arm portions are bowed outwardly on each side of the longitudinal axis of the instrument, with the longitudinal arm portions of each pair being relatively closely spaced to form a narrow opening in which the side of a stone may become wedged, and said pairs of longitudinal arm portions being relatively widely spaced apart, whereby said respective pairs of longitudinal arm portions are, in their relatively spaced apart positions, adapted to distend the walls of said duct into an elongated oval cross-section, and operating means, including movable hand operable means at the inner end of said long body and means interconnecting said movable hand operable means and said stone catching means, for moving said pairs of longitudinal arm portions between said relatively contiguous and spaced apart positions.

6. A medical instrument for removing kidney stones from the ureter comprising a long flexible body for insertion into said ureter, stone catching means at the outer end of said body, said stone catching means comprising a first and a second pair of laterally-spaced longitudinal arm portions movable together as a unit and connected together at their outer ends to form a pocket for catching said stones, the intermediate sections of said respective pairs of longitudinal arm portions being movable as a unit between relatively unbo-wed contiguous positions where they occupy a relatively small cross sectional area so as to be readily pushable around a stone lodged in said ureter, and relatively spaced apart positions where the respective pairs of longitudinal arm portions are bowed outwardly in opposite directions to a similar degree on each side of the longitudinal axis of the instrument, with the longitudinal arm portions of each pair being relatively closely spaced to form a narrow opening in which the side of a stone may become wedged, and said pairs of longitudinal arm portions being relatively widely spaced apart whereby said respective pairs of longitudinal arm portions are, in their relatively spaced apart positions, adapted to distend the walls of said ureter into an elongated oval cross-section, and operating means, including movable hand operable means at the inner end of said long body and means interconnecting said movable hand operable means and said stone catching means for moving said pairs of longitudinal arm portions between said relatively contiguous and spaced apart positions.

(References on following page) 9 References Cited in the file of this patent UNITED STATES PATENTS 3,374 1,612,697 Cecil Dec. 28, 1926 5,255 1,677,671 25,796

Councill July 17, 1928 5 10 FOREIGN PATENTS France Dec. 20, 1833 Great Britain 1825 Germany Jan. 30, 1884

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