Patent ID: 12193703

DETAILED DESCRIPTION

Embodiments set forth herein include handheld medical cutting instruments. The cutting instruments described herein are applicable to providing puncture-type incisions in the skin of a patient in which the blade of the instrument is inserted into the skin in a direction approximately perpendicular to the surface of the skin, and the width of the incision is controlled by the width of the blade. For example, unlike a scalpel, the blade may not be designed for dragging the cutting instrument along a length of the patient to create an elongated incision opening. the width of the blade may be selected based on the size of the incision opening that is required, such as to enable an implantable or insertable device, such as a catheter, an IMD (e.g., pacemaker and/or defibrillator), a dilator, and/or the like to enter the incision.

Relative to known cutting devices, the blade of the cutting instrument according to the embodiments described herein has relatively low cutting force required to penetrate the skin of the patient and a relatively short length, which reduces the risk of injury to blood vessels, bone, and other tissue caused by excessive cutting depth. For example, with reference to the graph10inFIG.1, the blade of the cutting instrument described herein may provide a peak cutting force that is similar to the peak cutting force of the 60-degree V-shaped blade20with a shorter length than the blade20. The cutting instrument described herein may achieve shallower cuts than the blade20without requiring significantly more cutting force than the blade20, for an overall improvement in performance and accuracy, and a reduced risk of injury to the patient.

The features, structures, or characteristics described herein may be combined in any suitable manner in one or more embodiments. In this description, numerous specific details are provided to give a thorough understanding of embodiments. One skilled in the relevant art will recognize, however, that the various embodiments can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obfuscation. The description is intended only by way of example, and simply illustrates certain example embodiments.

FIG.2illustrates a top-down view of a cutting instrument100in accordance with an embodiment. The cutting instrument100includes a handle102and a blade104. The blade104is coupled or attached to the handle102and projects from the handle102. For example, the blade104has a proximal end106at the handle102and extends from the proximal end106to a distal tip108of the blade104that is remote from the handle102. The distal tip108represents the point of the blade104farthest from the handle102. The cutting instrument100is arranged with respect to a width dimension191and a length dimension192that is perpendicular to the width dimension191.

The handle102is an elongated shaft that is designed to be grasped and held by the hand of an operator, such as a medical doctor or other medical professional. A portion of the handle102is omitted inFIG.2. The handle102may be composed of a rigid material, such as a thermoplastic or the like. In an embodiment, the material of the handle102may be molded (e.g., overmolded) onto the blade104to secure the blade104to the handle102. The handle102optionally includes rib-like protrusions110or other small features to enhance the grip of the operator on the handle102.

The blade104has a body112. The body112may be formed of a metal material, such as steel (e.g., stainless, high carbon, tempered, etc.) or another metal or metal alloy. The body112has a first side114and a second side116extending along a longitudinal center axis118. Only the first side114is shown inFIG.2. The second side116is opposite the first side114and is the same as (or at least similar to) the first side114with respect to size, shape, and appearance. The first and second sides114,116are planar in the illustrated embodiment, but may have a curvature in another embodiment. The longitudinal center axis118extends along the length dimension192and bisects the cutting instrument100along the width dimension191. For example, half of the width of the blade104is disposed on one side of the longitudinal center axis118, and the other half of the blade104is disposed on the other side of the longitudinal center axis118.

The body112of the blade104has at least three cutting edges120between the first and second sides114,116. The cutting edges120are sharpened, such as honed or whetted, for slicing through tissue with limited resistance. The body112may taper from the first and second sides114,116along the cutting edges120to provide the sharpened edges. In one or more embodiments, the cutting edges120are oriented at corresponding angles with respect to the longitudinal center axis118. For example, each of the corresponding angles may be less than 90 degrees, such that all cutting edges120are transverse to the longitudinal center axis118. In a non-limiting example, each of the corresponding angles may be no greater than (e.g., less than or equal to) 80 degrees relative to the longitudinal center axis118, and more particularly may be no greater than 70 degrees relative to the axis118. The cutting edges120are asymmetrically distributed with respect to the longitudinal center axis118. The cutting edges120are asymmetrically distributed such that the blade104is not symmetric about the longitudinal center axis118. For example, the half of blade104above the longitudinal center axis118inFIG.2is not a mirror image of the half of the blade104below the longitudinal center axis118.

In the illustrated embodiment, the body112of the blade104has three cutting edges120. The three cutting edges120include a first cutting edge122, a second cutting edge124, and a third cutting edge126. The second cutting edge124is disposed between the first and third cutting edges122,126. For example, the second cutting edge124extends from a distal point128of the third cutting edge126to the distal tip108of the body112. The distal tip108is defined by the vertex or intersection between the first cutting edge122and the second cutting edge124. The three cutting edges122,124,126, are linear in the illustrated embodiment. The first and third cutting edges122,126are located laterally from the longitudinal center axis118, such that the edges122,126are spaced apart from the axis118and do not intersect the axis118. The second cutting edge124intersects the longitudinal center axis118in the illustrated embodiment, and the distal tip108of the body112is laterally offset from the longitudinal center axis118. The distal tip108may align with the longitudinal center axis118in another embodiment, while retaining the asymmetry of the body112, as shown inFIG.7. Furthermore, the body112of the blade104may have more than three cutting edges120in another embodiment, such as four, five, six, or the like. For example, at least one additional cutting edge may be disposed between the second cutting edge124and the first cutting edge122and/or between the second cutting edge124and the third cutting edge126.

The body112also includes a first non-cutting edge130and a second non-cutting edge132. The non-cutting edges130,132are disposed between the first and second sides114,116of the body112. The first non-cutting edge130is located opposite the second non-cutting edge132, and the distance therebetween represents the define the width of the blade104. The non-cutting edges130,132are not sharpened for slicing through tissue, unlike the cutting edges120. As such, the non-cutting edges130,132may be relatively dull and/or blunt. The non-cutting edges130,132extend from the handle102at the proximal end106of the blade104. The first cutting edge122extends from the first non-cutting edge130. The third cutting edge126extends from the second non-cutting edge132.

FIG.3is a top-down view of the blade104of the cutting instrument100shown inFIG.2with the handle102omitted. The blade104is rotated relative to the orientation shown inFIG.2such that the distal tip108points downward inFIG.3. InFIG.3, the blade104is superimposed over an outline150that represents a symmetric, V-shaped blade as known in the art. For example, the outline150could represent the 60-degree blade20shown inFIG.1. Compared to the conventional symmetric, V-shaped blade150, the blade104in accordance with the embodiments described herein has a shorter length by a significant margin152. Furthermore, when compared to conventional symmetric, V-shaped blades that have a similar length, such as the 100 degree blade14inFIG.1, the angle at the distal tip108is more acute than the blade14, which reduces the peak cutting force by creating a steeper point to initiate the incision. The blade104advantageously reduces the blade length while maintaining characteristics of blades that have smaller (e.g., more acute) tip angles. For example, the more acute distal tip angle promotes lower initial puncture forces and the honed cutting edges120reduce the cutting force throughout the entire incision-generating process. This combination may provide the operator the ability to initiate the incision with less manual force applied than known blades of similar length, and to control the amount of pressure applied to accurately complete the incision to a desired width and depth.

FIG.4is an enlarged top-down view of the blade104of the cutting instrument100shown inFIGS.2and3. The various edges of the blade104define corresponding angles relative to each other and to the longitudinal center axis118. For example, the first and second non-cutting edges130,132are both oriented parallel to the longitudinal center axis118in the illustrated embodiment. The first cutting edge122is oriented at a first angle202relative to the longitudinal center axis118. The second cutting edge124is oriented at a second angle204relative to the longitudinal center axis118. The third cutting edge126is oriented at a third angle206relative to the longitudinal center axis118. Because the non-cutting edges130,132are parallel to the longitudinal center axis118, the first, second, and third cutting edges122,124,126are also oriented at the respective first, second, and third angles202,204,206relative to the first and second non-cutting edges130,132. The first, second, and third angles202,204,206are each less than 90 degrees, and may be no greater than 80 degrees.

In an embodiment, the first and third angles202,206are each independently between 15 degrees and 45 degrees. As used herein, a range of angles is inclusive of the endpoints such that 15-45 degrees means no less than 15 degrees and no greater than 45 degrees. In a non-limiting example, the first and third angles202,206are each independently between 20 degrees and 40 degrees. The first angle202optionally may be the same as the third angle206, such that the first and third cutting edges122,126are oriented at a common first angle with respect to the longitudinal center axis118. For example, the first and third angles202,206may be 30 degrees in the illustrated embodiment. In an alternative embodiment, the first angle202is different from the third angle206.

The second angle204defined between the second cutting edge124and the longitudinal center axis118is different from the first and third angle202,206. The second angle204may be greater than the first and third angles202,206, and may be between 45 degrees and 80 degrees. In a non-limiting example, the second angle204is between 50 degrees and 70 degrees. The second angle204may be 60 degrees in the illustrated embodiment. In the illustrated embodiment in which the first and third angles202,206are 30 degrees and the second angle204is 60 degrees, the blade tip angle208, defined between the first cutting edge122and the second cutting edge124, is 90 degrees. The first, second and third angles202,206and208define an asymmetrical distribution for the first, second and third cutting edges122,124,126with respect to the longitudinal center axis118.

As shown, the blade tip108is offset from the longitudinal center axis118. In other embodiments, the blade tip angle208may be greater or less than 90 degrees, such as between 80 degrees and 100 degrees.

The width210of the blade104is the distance between the first and second non-cutting edges130,132. The length212of a cutting portion of the blade104is the distance from the distal tip108to the proximal end214of the honed or tapered surfaces216of the body112. In an embodiment, the lengths and orientations of the cutting edges122,124,126may be designed based on total width210and/or length212constraints. One constraint may designate that a width218of the second cutting surface124(parallel to the width dimension191shown inFIG.2) is within a designated range of the overall width210of the blade104. For example, the width218of the second cutting surface124may be between 15% and 50% of the blade width210(inclusive of the end points). In the illustrated embodiment, the width218is 37%-40% of the blade width210.

The cutting instrument100according to the embodiments of the present disclosure has been experimentally tested to compare the cutting instrument100to conventional blade types, including the symmetric, V-shaped blades.FIG.5is a diagram comparing the cutting forces between the cutting instrument100described herein and a conventional V-shaped blade300. The V-shaped blade300used as the reference in the evaluation has a 100 degree tip angle, similar to the blade16inFIG.1. Bench testing was performed in which the blades104,300were punctured vertically into a synthetic muscular skin tissue plate with the tissue mounted and backed by a foam block. The asymmetric blade104of the cutting instrument100achieves lower cutting force than the reference blade300while maintaining a desirable short blade length to avoid deep cuts that could unintentionally sever blood vessels, scrape bone, or the like.

FIG.6illustrates a top-down view of the cutting instrument100in accordance with a second embodiment. The cutting instrument100has a blade404that is similar to the blade104shown inFIGS.2-5. For example, the blade404has a body412with a first cutting edge422, a second cutting edge424, and a third cutting edge426that are oriented at corresponding angles with respect to the longitudinal center axis118, and the cutting edges422,424,426are asymmetrically distributed with respect to the longitudinal center axis118. The angles define the asymmetrical distribution for the first, second and third cutting edges422,424,426with respect to the longitudinal center axis118. However, unlike the blade104, a distal tip418of the blade404, which is at the vertex or intersection between the first and second cutting edges422,424, aligns with the longitudinal center axis118. In the illustrated embodiment, the blade404is asymmetric about the longitudinal center axis118, even though the distal tip418aligns with the axis118, because the upper half of the blade404above the axis118inFIG.6is not a mirror image of the lower half of the blade404below the axis118. For example, the upper half of the blade404resembles the symmetric V-shaped blades, but the lower half does not. There is only one cutting edge422above the axis118, and two cutting edges424,426below the axis118. Experimental testing has demonstrated similar performance between the two embodiments of the asymmetric blades104,404. The blade404with the centered blade tip418required only slightly higher total puncture (or cutting) force than the blade104with the offset blade tip108.

FIG.7is a top-down view of a blade504of the cutting instrument100in accordance with a third embodiment. The blade504is similar to the blade104shown inFIGS.2through5. For example, the blade504has a distal tip518that is offset from the longitudinal center axis118of the blade504. The blade504differs from the blade104and the blade404shown inFIG.6because the blade504has four cutting edges, including a first cutting edge522, a second cutting edge524, a third cutting edge526, and a fourth cutting edge528. The first and third cutting edges522,526extend from different non-cutting edges of the blade504. The fourth cutting edge528extends from a distal point529of the first cutting edge522to the distal tip518. The second cutting edge524extends from a distal point of the third cutting edge526to the distal tip518. The distal tip518is defined at the vertex or intersection between the second and fourth cutting edges524,528. The cutting edges522,524,526,528are linear, honed edges. In the illustrated embodiment, the first, second, and third cutting edges522,524,526are laterally spaced apart from the longitudinal center axis118, and the fourth cutting edge528intersects the longitudinal center axis118. The cutting edges522,524,526,528are asymmetrically distributed with respect to the longitudinal center axis118.

Each of the cutting edges522,524,526,528is oriented transverse to the longitudinal center axis118, such that the corresponding angle between the respective cutting edge and the axis118is less than 90 degrees. For example, the first, second, third, and fourth cutting edges522,524,526,528are oriented at respective first, second, third, and fourth angles relative to the longitudinal center axis118. The first and third angles may be each independently no less than 20 degrees and no greater than 40 degrees, and the second and fourth angles may be no less than 45 degrees and no greater than 80 degrees (such as no less than 50 degrees and no greater than 70 degrees). The first and third angles may be the same or different from each other. The second and fourth angles may be the same or different from each other.

The cutting instrument with asymmetric blade as described herein advantageously enables accurate control over the width and depth of puncture-type incisions while reducing the amount of force that is required to be exerted on the cutting instrument relative to cutting instruments with blades of comparable length. The blade of the cutting instrument described herein is a hybrid design that provides the both the penetration benefit of a longer, narrow tip angle V-shaped blade and the shallow depth control of a wider tip angle V-shaped blade, while avoiding or reducing the shortcomings of these two V-shaped blades.

It will be readily understood that the components of the embodiments as generally described and illustrated in the Figures herein, may be arranged and designed in a wide variety of different configurations in addition to the described example embodiments. Thus, the more detailed description of the example embodiments, as represented in the Figures, is not intended to limit the scope of the embodiments, as claimed, but is merely representative of example embodiments.

Reference throughout this specification to “one embodiment” or “an embodiment” (or the like) means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” or the like in various places throughout this specification are not necessarily all referring to the same embodiment.

It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the inventive subject matter without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the inventive subject matter, they are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to one of ordinary skill in the art upon reviewing the above description. The scope of the inventive subject matter should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(f) unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.