Patent Application
20200222040
The claimed invention relates generally to surgical instruments for fastening suture, and more particularly to a mechanical fastener which is suitable for securing suture, particularly of very fine diameter.
Malleable suture fasteners such as the sleeves sold under the trademarks Ti-KNOT® and COR-KNOT® by LSI Solutions, Inc. are a significant improvement over hand or instrument-tied knots in laparoscopic surgical procedures. The sleeves, which are made of a malleable material that has proven safe with prolonged exposure to body tissue, are slid over two or more strands of suture and deformed or crimped to secure the strands of suture.
An exemplary crimping instrument is shown in U.S. Pat. No. 7,235,086, entitled “CRIMPING INSTRUMENT WITH MOTION LIMITING FEATURE”, assigned to LSI Solutions, Inc., of Victor, N.Y. Such crimping devices have a handle with an actuator lever that is movable relative to the handle. A hollow shaft extends from the handle to a distal end of the shaft. Suture ends can be threaded through a crimping sleeve held between a hammer and an anvil which are located in the distal end of the shaft. The suture ends pass out a hole in the side of the shaft, and the device can be used to position the crimping sleeve at a desired location on the suture relative to a surface through which the suture has been secured (for example, tissue, a replacement anatomical structure such as a heart valve, or an augmentive anatomical structure such as a heart valve annulus).
Squeezing the actuator lever towards the handle causes a wedge, located in the shaft, to advance and to force the hammer into the crimping sleeve. The hammer crimps the crimping sleeve against the anvil, and the suture is held tightly by the deformed sleeve. A blade may also be incorporated within the shaft and can be simultaneously moveable by the actuator lever in order to trim the suture ends.
Such instruments for attaching suture fasteners have proven to be very effective for sutures of a 2-0 and a 3-0 size. The United States Pharmacopeia (U.S.P.) specifies suture sizes as follows:
The 2-0 and 3-0 sutures (0.3 mm to 0.2 mm diameter) used with existing mechanical fastener products like the COR-KNOT® and Ti-KNOT® devices are useful in a wide range of surgeries where it is desired to approximate soft tissue and prosthetic materials. Unfortunately, these existing products are not indicated for use with smaller diameter sutures, such as, but not limited to 6-0, 7-0, and 8-0 sutures, which are much smaller in diameter (ranging from 0.07 mm down to 0.04 mm in diameter). These extremely small diameter sutures are useful in a wide variety of surgeries, such as coronary artery bypass graft (CABG) procedures, but it is not possible to use the existing COR-KNOT® or Ti-KNOT® crimpable sleeves (mechanical fasteners) with these small sutures. While these existing fasteners can be crimped onto such small suture, the sutures slip out of the fasteners under too low of a tension, making them incompatible.
It has been suggested that the dimensions of the COR-KNOT® fasteners simply be scaled down so that a proportionally smaller mechanical fastener could be used to secure smaller sutures, such as 6-0, 7-0, and 8-0 sutures. However, this has been attempted, including scaling down the critical portions of the device which crimps the mechanical fastener, and the results were not ideal. Hammer and anvil profiles, as well as mechanical fastener dimensions have proven not to be directly scalable to smaller suture, and as such design work related to different suture sizes from what is commercially available for mechanical suture fasteners is a non-obvious and highly exploratory endeavor.
Therefore, there is a need for a mechanical suture fastener which enables reliable suture holding performance when crimped onto 6-0, 7-0, and 8-0 suture.
A mechanical suture fastener is disclosed. The mechanical suture fastener includes a crimpable sleeve defining a channel therein. The crimpable sleeve also has a sleeve length, a channel diameter, and a sleeve length to channel diameter ratio of at least 4.0.
The mechanical suture fastener also includes a flange joined to the crimpable sleeve on a distal end of the sleeve. The flange further includes a distal opening which is in communication with a proximal opening defined by the crimpable sleeve.
The mechanical suture fastener also includes an inner flange radius of at least 0.007 inches.
It will be appreciated that for purposes of clarity and where deemed appropriate, reference numerals have been repeated in the figures to indicate corresponding features, and that the various elements in the drawings have not necessarily been drawn to scale in order to better show the features.
The table below illustrates different embodiments of different dimensions which have been discovered to provide suitable holding force and crimpable knot performance when used with 6-0, 7-0, and 8-0 suture.
It has been discovered that a crimpable mechanical fastener with an axial length to channel diameter ratio from about 5.19 to about 5.39 results in reliable suture holding force when the mechanical suture fastener is crimped onto 6-0, 7-0, or 8-0 suture. Similarly, it has been discovered that a crimpable mechanical fastener with a sleeve length to channel diameter ratio of about 4.69 to about 4.87 results in reliable suture holding force when the mechanical suture fastener is crimped onto 6-0, 7-0, or 8-0 suture. These ratios may be especially relevant for crimpable fasteners having a sleeve wall thickness of approximately 0.004 inches, but not necessarily limited to such thickness. The sleeve length to channel diameter ratio may be especially helpful in designing such fasteners, since it appears to be relatively independent of the flange dimensions, which may separately be chosen for criteria such as alignment of the mechanical suture fastener into a crimping device and for non-traumatic tissue interface. Other dimensional ratios and relationships are being explored in order to guide the designs for these types of fasteners, and such discoveries will be pursued in follow-on patent applications.
It has also been discovered that embodiments having an inner flange radius of approximately about 0.007 to 0.011 inches or larger, and preferably 0.011 inches or larger, may be helpful in preventing the mechanical suture fastener from cutting the 6-0, 7-0, or 8-0 suture held therein when the fastener has been crimped onto such suture. As mentioned with respect to other design parameters and dimensions of the mechanical suture fastener described herein, simply reducing the size of previously known embodiments of mechanical suture fasteners has proven ineffective in balancing desirable properties and quality measures such as reduced size, sufficient suture holding force while avoiding new issues such as suture cutting or shearing. Therefore, merely proportionally reducing dimensions or scaling down previous embodiments of mechanical suture fasteners resulted in an inner radius between the flange end and the inner channel that resulted in shearing or cutting the thinner 6-0, 7-0, or 8-0 suture which was held and crimped within the mechanical fastener.
Various advantages of a mechanical suture fastener have been discussed above. Embodiments discussed herein have been described by way of example in this specification. It will be apparent to those skilled in the art that the forgoing detailed disclosure is intended to be presented by way of example only, and is not limiting. Various alterations, improvements, and modifications will occur and are intended to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested hereby, and are within the spirit and the scope of the claimed invention. Additionally, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations therefore, is not intended to limit the claims to any order, except as may be specified in the claims. Accordingly, the invention is limited only by the following claims and equivalents thereto.
This patent application claims priority to U.S. Provisional Patent Application No. 62/793,352 filed Jan. 16, 2019 and entitled “MECHANICAL SUTURE FASTENER.” The 62/793,352 application is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62793352 | Jan 2019 | US |
