Disposable Surgical Scissors

Abstract

Disposable scissors including a pair of blades, each having a cutting section, mounting section pivotally mounted together, and a camming section inclined and cooperating with a like camming section of the opposed blade. The camming sections of the blades slidably engage as they are moved toward closed positions in order to urge the cutting sections together and provide cutting pressure. The camming sections are provided with tabs which abut to limit movement of the blades beyond their closed positions.

Description

This invention generally relates to scissors, and more particularly to disposable surgical scissors.

Surgical scissors of the prior art are made entirely of stainless steel or other material too expensive for permitting disposal of the scissors after use. Accordingly, it is necessary to reuse such scissors and resterilize the same after each use. Such procedure requires accurately kept inventories as well as expenditures of time and money to assure satisfactory sterilization.

Another disadvantage of prior art surgical scissors occurs in the design thereof. The pivot of such scissors retains the blades in intimate contact, thereby trapping bacteria and preventing penetration of sterilization steam or fluid.

It has been found that most efficient scissors' cutting if obtained if there is but a single point contact between the cutting edges. It is desirable to maintain such point contact throughout the cutting operation, from the point of initial contact of the cutting edges, at their fully opened positions, to the final point contact at the tips of the blades, at their fully closed positions. Such action is particularly desirable in surgical scissors to eliminate wasted cutting motion and to permit the very tips of the cutting blades to cut sutures, for example, when the tips are inserted adjacent to or within a portion of a patient's body with only a small amount of space available for cutting.

In the scissors of the prior art, desired engagement of the cutting edges is assured by hollow grinding the inside surfaces of the blades and by twisting the blades lengthwise to a longitudinal bowed configuration. Such configuration requires precision machining and results in substantial increase in the initial cost thereof.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the preferred embodiment, a pair of scissors is provided with a pair of pivotally connected handles and a pair of opposed cutting blades mounted respectively on the handles. The blades each have an inner surface and a cutting edge extending from the pivotal connection in a direction opposite to that of its associated handle. Each blade further includes a camming surface on the side of the pivotal connection opposite that of its respective cutting edge, which camming surface is formed by bending a portion of the blade, toward the inner surface of the opposed blade. Upon closing the scissors, the camming surfaces cooperatively engage each other throughout the cutting operation and thus continuously urge the cutting edges to engage each other at a point contact therebetween. Accordingly, the cooperating camming surfaces provide pressure at the point contact of the cutting edges. The blades are maintained in spaced relationship at their pivot by the camming sections and also by the point contact with an opposed blade. This prevents entrapment of bacteria at the pivot by allowing penetration of sterilizing fluid or steam.

To further insure only a single point contact between the blades, such blades are longitudinally curved along the cutting edges so that they cross over each other at the point contact. As the scissors are closed during a cutting operation, the point contact traverses toward the tips of the cutting edges resiliently forcing them from their crossed over configurations to adjacent relationship. Additionally, the camming surfaces apply substantial cutting pressure at the point contact throughout the cutting operation. Accordingly, the preferred embodiment provides a desired point contact without a need for special machining and hollow grinding of the blades. Moreover, the blades can be formed with either an inclined cutting edge, for example, inclined at an angle of approximately 80.degree. or a non-inclined cutting edge.

To limit travel of the cutting blades beyond the last desired point contact between their tips, tabs, provided on the camming surfaces, engage each other, thereby preventing further closure of the scissors.

According to a further feature of the preferred embodiment, the cutting edges engage at their initial point contact and define therebetween an angle in the range of 30.degree.-35.degree.. The magnitude of such an angle is critical particularly when it is desirable to cut surgical cloth or gauze. It has been found that with cutting edges contacting at larger angles, the gauze is pushed away from the point contact until an angle of 35.degree. is attained upon further closure of the blades.

OBJECTS OF THE INVENTION

Accordingly it is an object of the present invention to provide disposable surgical scissors.

Another object of the present invention is to provide scissors having blades which are spaced from each other at a pivot to prevent entrapment of bacteria by permitting circulation of sterilizing fluid or steam at the pivot.

A further object object of the present invention is to provide surgical scissors having curved blades which cross over each other to establish a point contact throughout a cutting operation.

Still another object of the present invention is to provide scissors with blades having camming surfaces thereon which cooperate to continuously apply cutting pressure at the point contact of the blades.

Still a further object of the present invention is to provide scissors with tabs which engage to limit travel of the cutting blades beyond the last point contact between their tips thereof.

Other objects and many attendant advantages of the present invention will become apparent upon perusal of the following detailed description taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a preferred embodiment of the present invention;

FIG. 2 is an exploded perspective of the embodiment shown in FIG. 1;

FIG. 3 is an enlarged plan view of a cutting blade, with an opposed cutting blade shown in phantom outline;

FIG. 4 is a section taken along the line 4--4 of FIG. 3;

FIG. 5 is a elevation of the preferred embodiment illustrated in FIG. 3;

FIG. 6 is a section taken along the line 6--6 of FIG. 1;

FIG. 7 is a fragmentary elevation of the preferred embodiment with the blades shown in their closed positions and with the handles shown in section;

FIG. 8 is a schematic of the cutting blades according to the present invention, and shown crossed over each other at a point contact intermediate their tips, and

FIG. 9 is a schematic of the cutting blades at their fully closed positions.

With more particular reference to the drawings, and initially to FIGS. 1 and 2 thereof, scissors according to a preferred embodiment includes a pair of handles 12 connected by a rivet 14. A pair of cutting blades 16 are respectively connected to the handles 12. Since the handles 12 are of identical configuration, only one thereof will be described in detail. As shown in FIG. 2, each handle 12 is formed of a relatively inexpensive flexible plastic, such as fiber glass reinforced nylon, polycarbonate, polypropelene, polyphenaline-oxide, or a modified polyphenaline-oxide (sold by General Electric Corporation under the trademark"NORYL"). Each handle 12 has a generally circular hub portion 18, an elongated intermediate section 20 and a finger piece 22. The hub 18 includes an aperture 24, receiving the rivet 14, and an upstanding hub sector 26, positioned thereon adjacent to the aperture 24.

The intermediate section 20 is formed with a reinforcing rib 28 on its inner side, to strengthen the handle and to provide a stop for preventing overstressing of the handle upon completion of the cutting operation.

The cutting blades 16 are more clearly illustrated in FIGS. 3 and 5 and are each of identical configuration. It is contemplated that each blade is stamped from sheet material preferably stainless steel. Each blade 16 has an inner surface 30, and is formed with three distinctly shaped sections, including a cutting section 32, a mounting section 34, and a camming section 36. Each cutting section 32 has an inner cutting edge 38 with said surface 30 being uniformly inwardly curved along said cutting edge. The cutting edge 38, as shown in FIG 4, is inclined to an angle Alpha with the inner surface 30 which in the preferred embodiment of the invention is approximately 80.degree.. However, the cutting edge may be inclined at other angles and in fact be non-inclined with Alpha equal to 90.degree., yet still produce satisfactory cutting.

Cutting section 32 is further characterized by a tapered configuration provided by an outer edge 39 which is inclined with respect to the cutting edge 38 and which terminates in a tapered tip 58, which tip is also beveled adjacent to surface 31. The tapered and beveled configuration of the tip readily allows insertion thereof into a limited access area, for example, a cavity in the body of a patient. Additionally, the tip is rounded at its outer edge 59 immediately adjacent to the edge 38 to avoid inadvertent puncturing or abrasion by the tip during use.

Mounting section 34 is relatively planar against the planar inner surface 40 of the hub 18 when each blade is assembled to a handle. The section 34 is provided with an aperture 42 in alignment with an aperture 24 in the hub 18 in order to received the rivet 14, which accordingly holds a handle 12 and a blade 16 in their assembled configuration. In addition, the mounting section 34 is provided with a flat edge portion 44 which registers against a shoulder portion 46 of the hub sector 26. Engagement of the edge 44 and the shoulder 46 maintains the blade in fixed position with respect to the hub.

Camming section 36 of each blade 16 is inclined out of the plane of the mounting section 34, for example, by a bending operation, and into the curved plane of the inner surface 30. In this manner, the camming section 36 is provided with an arcuate edge 50 intersecting the intersection line 48 and forming thereby a relatively narrow inclined cam surface 51. The intersection line 48 extends away from the edge 50 and forms a relatively wide inclined cam surface 52 integral with the surface 51 and immediately adjacent to the edge 44. The surface 52 also includes an extended tab portion 54 projecting from the edge 50 and disposed adjacent to the edge 44.

With the scissors assembled, the blades will be mounted to respective handles and pivotally connected in opposed relationship by the rivet 14. With the scissors in a fully opened position as shown in FIG. 3, the cam surface 52 of each camming section will abut a mounting section 34 of the opposed blade. Such action maintains a spacing between the mounting sections 34 preventing entrapment of bacteria and allowing penetration of sterilizing fluid or steam to clean portions of the scissors surrounding the rivet.

Upon closure of the handles, the cam surfaces 51 of the section 36 will mutually overlap and slidably engage each other simultaneously as the cutting edges engage each other at the initial point contact immediately adjacent the mounting sections 34.

With reference to FIG. 1, it is shown that when the cutting edges engage at their initial point contact, an angle Beta of 30.degree.-35.degree. is defined therebetween. The magnitude of such an angle is critical, particularly when it is desirable to cut surgical cloth or gauze. It has been found that with cutting edges contacting at larger angles the gauze is pushed away from the point contact of the edges until an angle of 35.degree. is attained upon further closure of the blades.

As shown in FIGS. 8 and 9, the blades initially cross over each other at the initial point contact 56, due to their curved configurations, and the engaged cam surfaces 51 of the camming sections 36 bias the blades toward each other and thereby insure application of pressure at the point contact. Such contact insures that the gauze is cut rather than merely pushed forward or pinched between the cutting edges.

As the blades are progressively closed, the point contact progressively traverses toward the blade tips. Also, as shown in FIG. 3, the cam surfaces 51 progressively slidably overlie each other and the surfaces 52 are progressively brought into slidable overlying relationship. Such action of the cam surfaces insure maintenance of the mentioned pressure at the point contact as the blades are progressively closed. More particularly, the cam surfaces 52 project outwardly from the surface 30 a greater amount than do the cam surfaces 51. Thus, as the point contact traverses progressively toward the tips and away from the cam surfaces, a progressively increased camming action is achieved as the camming surfaces 52 are progressively brought into overlying relationship. As the blades are moved to the closed positions, the portions of the blades rearwardly of the point contact 56 are forced to separate and become supported only by the engaged camming sections 36 and the cutting edges at the point contact. The blade positions directly behind the point contact are urged outwardly permitting such portions to assume side-by-side positions. When the blades are fully closed, they will be entirely in side-by-side positions and laterally engaged at their tips 54 (as shown in FIG. 9) and with cam surfaces 52 of the camming section 36 in overlapping engagement.

As shown in FIG. 8, the tabs 54 engage each other and serve to limit pivotal movement of the blades 16 beyond the desired closed positions thereof. Continued application of closing forces to the finger pieces 22 will not cause the tips 58 to move past each other. However, since the handles 12 are formed of resilient material, they will bend in response to the closing forces. Accordingly, to prevent overstressing of the handles, a rib 28 is provided on the inner surface of each handle extending from adjacent to the hub 18 to a position adjacent to the finger piece 22 serving to reinforce the handle. In addition, should the operator using the scissors continue to apply force to the finger pieces after the tabs 54 are engaged, the handles 12 resiliently bend until the ends 62 of the ribs 28 engage and prevent further flexing of the handles. When the blades are moved to fully opened positions somewhat beyond the initial point contact of the cutting edges, the outer edges 39 engage the ends 64 of the rib on opposed handles whereby further movement thereof toward open positions is prevented.

That the scissors open somewhat beyond the initial point contact is an advantage, since as shown in FIG. 3 each of the mounting sections 34 includes, an arcuate edge configuration 65 provided generally between the cutting edges. This permits full insertion of gauze between the cutting edges against the arcuate edge configuration 65 prior to a cutting operation. Since the edge configuration is arcuate, the gauze is not pushed away thereby upon closing of the cutting edges to the initial point contact. Thus immediate cutting action takes place adjacent the arcuate configurations 65 of said mounting sections 34 as the cutting edges are closed to their initial point contact.

It is thus apparent that an efficient and readily disposable scissors have been provided which are readily adapted to cut surgical material from the first point contact between the cutting edges to the very tips of the cutting blades. The forces required for cutting of the scissors is reduced substantially to that applied in the prior art since the camming action of the blades supplies the pressure required to maintain the edges in the desired point contact during cutting. It is further evident that all of the critical design characteristics of the scissors are provided on stainless steel identically stamped blades which are separate from the handles 12, thereby greatly facilitating fabrication of the device at substantially reduced cost.

Other embodiments and modifications of the invention are not limited to the embodiment particularly, and various changes and modifications may be effected by one skilled in the art without departing from the scope from the appended claims.

Claims

What is claimed is:

1. In a pair of scissors having a pair of handles pivotally connected together and cutting blades having cutting edges and mounted respectively on said handles, said cutting blades being pivotally movable into mutual contact along said cutting edges to close positions during a cutting operation, the improvement comprising: a. a mounting section on each of said blades, said mounting section including an arcuate edge configuration disposed generally between said cutting edges of said cutting blades, with said cutting blades being pivotally movable into mutual contact along their cutting edges to define an initial point contact immediately adjacent to said arcuate edge configurations; b. a camming section on each of said blades inclined and projecting from a corresponding mounting section and defining a relatively narrow camming surface and a relatively wide camming surface, said camming section of one of said cutting blades engageable with a mounting section of the other of said cutting blades to maintain a spacing between said mounting sections of said cutting blades thereby allowing sterilizing fluid or steam therethrough; c. stop means on said relatively wide inclined cam surface of each of said blades; d. said relatively narrow camming surfaces of said cutting blades being mutually overlapped and biasing said cutting blades towards each other to apply pressure at said initial point contact as said blades are pivotally moved into mutual engagement; e. said cutting blades being progressively pivotally movable slidably over each other to close position during a cutting operation and causing said point contact to traverse progressively along said cutting edges of said cutting blades in a direction away from said camming sections; f. said relatively wide inclined cam surfaces being mutually brought progressively into mutual slidable overlying relationship as said blades are progressively pivotally moved to closed positions during a cutting operation to bias said blades towards each other and to apply pressure at said traversing point contact during a cutting operation; and g. said stop means on each of said cutting blades being engageable on each other with said relatively wide inclined cam surfaces in overlying relationship thereby limiting further pivotal movement of said cutting blades beyond said closed portions.

2. The structure as recited in claim 1 and further including: a. an anti-overstressing rib on each of said handles, said ribs being mutually engageable to prevent over-stressing of said handles when said cutting blades are pivotally moved to closed positions during a cutting operation.