Patent Description:
An example of a device and method for joining a suture is shown in <CIT>. The present disclosure relates to a magnetic suture. More particularly, the disclosure relates to a suture having a magnet at one end (a magnetic tip). Such a magnetic suture may be used, for example, in a magnetic U-stich device, like that described in <CIT>.

As described in the '<NUM> patent, a suture having a magnetic tip is inserted into a body cavity of a patient (to be withdrawn by a magnetic probe of opposite polarity) via a hypodermic needle. In some embodiments, the suture and magnetic tip are advanced in the hypodermic needle via a cannula, where the magnet of the magnetic tip has a diameter greater than an inner diameter of the cannula. Therefore, an insertion force on the cannula into the hypodermic needle is transferred to the magnet, and thus to the suture that is also in the hypodermic needle. Put another way, inserting the suture having a magnetic tip can impart a force on the magnetic tip and away from the suture itself.

As seen in <FIG>, according to a current design of a magnetic suture, the magnetic suture <NUM> includes a small cylindrical magnet <NUM>, a thin tubular stainless steel sleeve (hereinafter, the "ferrule") <NUM>, a suture <NUM> having a knot <NUM> at one end, and room-temperature curing adhesive <NUM> for holding the suture <NUM>/knot <NUM>, magnet <NUM>, and ferrule <NUM> together. The ferrule <NUM> may be a laser cut stainless steel hypodermic tube having a constant inner diameter and outer diameter. The magnet <NUM> is flush at one end with the end of the ferrule <NUM>, and the adhesive <NUM> secures the suture <NUM>/knot <NUM>, magnet <NUM>, and ferrule <NUM> together at the other end.

Considering this, some designs of magnetic sutures can suffer failure by detachment of the magnet from the suture with only small amounts of tension during use and testing (e.g., during insertion described above). Further, manufacturing and assembly techniques for attaching a magnet to the end of a suture can suffer from a number of deficiencies. For example, manufacturing tolerances can be small, making assembly and production on a mass scale difficult. Additionally, errors in the alignment of the magnet relative to the suture can affect functionality of suturing devices. For example, an off-center or angled magnet may not fit within a hypodermic needle and/or may not be able to be advanced through the needle.

The invention is defined in independent claim <NUM> and <NUM>. Certain optional features of the invention are defined in the dependent claims. According to the present disclosure, a magnetic suture comprises: a ferrule having a small opening at an end of a tapered region, and having a large opening at an end of a straight region, wherein the small opening is at an opposite end of the ferrule than the large opening and at least a portion of the tapered region has an inner diameter that is tapered toward the small opening, and an inner diameter of the small opening being substantially equal to an outer diameter of the suture; a suture extending from the small opening; and a magnet at least partially within the straight region. Further, at the end of the straight region and opposite the large opening, the ferrule has a shoulder where the inner diameter of the ferrule begins to decrease in the tapered region and the shoulder prevents the magnet from being inserted into the tapered region.

In various examples of the above disclosure, the suture is knotted and the knot is located within the tapered region, between the magnet and the small opening; the magnetic suture further comprises an adhesive within the tapered region, between the magnet and the small opening; an inner diameter of the straight region is substantially constant and is substantial equal to an outer diameter of the magnet; an inner diameter of the small opening is substantially equal to a diameter of the suture; and/or the magnet extends from the large opening.

According to the present disclosure, a method comprises knotting a suture at a first end of the suture; threading a second non-knotted end of the suture through a small opening of a ferrule, such that the knot is in an interior of the ferrule; applying adhesive to an interior of the ferrule; and inserting a magnet into a large opening of the ferrule, wherein: the small opening is at an opposite end of the ferrule than the large opening, and the knot is between the magnet and the small opening.

In various examples of the above disclosure, the method further comprises: prior to threading the second non-knotted end of the suture through the small opening of the ferrule, cutting a portion of remaining strand of the suture beyond the knot at the first end; the threading is performed by vacuum tooling; the threading comprises: with a vacuum tool, picking up the ferrule and centering the ferrule with respect to a vacuum applied by the vacuum tool, and with the vacuum tool, sucking the second non-knotted end of the suture through the small opening of the ferrule, such that the knot is in an interior of the ferrule; the method further comprises: cleaning excess adhesive that escapes through the small opening of the ferrule; the small opening of the ferrule opens to a tapered region of the ferrule, the large opening of the ferrule opens to a straight region of the ferrule, the suture extends from the small opening, and the magnet is at least partially within the straight region; and/or the magnet extends from the large opening.

A magnetic suture and its manufacturing method according to the present disclosure overcome the above-discussed deficiencies, thereby reducing waste of components and time while increasing the speed and reliability of magnetic suture assembly.

As seen in <FIG>, a magnetic suture <NUM> of the present disclosure has a ferrule <NUM> with a tapered region <NUM> in continuity with or adjacent to a straight region <NUM>. In particular, the ferrule <NUM> has a tapered region (also referred to herein as a "transition region") <NUM> where at least the inner diameter decreases (variably or continuously), and that opens, to a smaller opening <NUM>; and a straight region <NUM> preferably having a substantially constant inner diameter that opens to a larger opening <NUM>. The tapered region <NUM> may only be tapered for a portion of its length between the small opening <NUM> and the straight region <NUM> but may be tapered at a continuous or variable degree for an entirety of the region <NUM>. Preferably the small opening <NUM> is only slightly larger than, or substantially equal to, the outer diameter of the suture <NUM>; and the straight region <NUM> has an inner diameter that is slightly larger than, or substantially equal to, the outer diameter of a cylindrical magnet <NUM> therein. The ferrule <NUM> does not need to extend the length of the magnet and thus the large opening <NUM> does not need to be flush with the end of the magnet <NUM>. In other words, the magnet <NUM> may extend out of the large opening <NUM>.

At the other end of the straight region <NUM> (opposite the large opening <NUM>), the ferrule <NUM> has a natural "stop" or shoulder <NUM> where the inner diameter of the ferrule <NUM> begins to transition/decrease in the transition region <NUM>. The magnet <NUM> cannot be inserted beyond the shoulder <NUM> into the transition region <NUM> of the ferrule <NUM> because the inner diameter of the ferrule <NUM> is less than the outer diameter of the magnet <NUM>. Although the shoulder is naturally created by the shape of the ferrule <NUM>, the ferrule may also include a physical stop (such as a shelf) extending perpendicular to the sides of the ferrule in the straight region <NUM> at the shoulder.

Additionally, the suture <NUM> is knotted, with the knot <NUM> located within the transition region <NUM> of the ferrule <NUM>. The ferrule <NUM>, suture <NUM>, and magnet <NUM> can be held together via adhesive <NUM> within the transition region <NUM>.

According to this structure, because the tapered ferrule <NUM> creates a mechanical stop for the suture knot <NUM> at the small opening <NUM>, and the magnet <NUM> and adhesive <NUM> are forced against the knot <NUM>, extra suture <NUM> can be accommodated in the ferrule <NUM>. This lessens the risk of the suture unraveling under tension. Further, the knot <NUM> and ferrule <NUM> create a natural mechanical joint as a fail-safe even if the adhesive <NUM> fails.

Still further, the tapered region <NUM> of the ferrule <NUM> helps ensure that the suture is straight and centered relative to the ferrule <NUM> and magnet <NUM>, thus preventing the above-noted crooked assemblies. The tapered region <NUM> of the ferrule also permits movement of the suture <NUM> while the adhesive <NUM> cures because the position of the suture <NUM> is guided by the shape of the tapered region <NUM> of the ferrule <NUM> and the position of the magnet <NUM> therein. In other words, the knot <NUM> of the suture is sandwiched between the magnet <NUM> and the small opening <NUM> of the ferrule <NUM>, thereby increasing the strength of adhesion between the elements of the magnetic suture <NUM> and helping to ensure proper position of the knot <NUM> and suture <NUM> within the transition region <NUM> during curing of the adhesive.

The magnetic suture <NUM> of <FIG> can be manufactured and assembled according to the method illustrated in <FIG>. As seen therein, the method begins by tying a knot <NUM> near one end of a suture. Next, the small remaining strand of the suture beyond the knot is cut <NUM> in a manner that does not damage the knot itself. It is not necessary to cut as close to the knot as possible. Thus, the magnetic suture may be manufactured with greater tolerance relative to current designs and any potential damage to the knot from the cut is minimized.

After the knot is formed, the non-knotted end of the suture is threaded <NUM> through the small opening of the ferrule from the large opening side of the ferrule. The knot of the suture is too large to go through the small opening of the ferrule, and therefore hits a consistent mechanical stop when the suture is threaded or otherwise pulled through the small opening. In some embodiments, this can be accomplished using vacuum tooling. For example, the ferrule can be picked up and centered at the end of the vacuum tooling (due to the shoulder created by the tapered end of the ferrule), and the non-knotted end of the suture can be sucked through the small opening of the ferrule with an applied vacuum such that the vacuum essentially threads the ferrule with the knot in the tapered region. Using a vacuum can reduce reliance on a steady hand and keen eye of a person doing the assembly.

Following threading, a drop of adhesive is applied <NUM> to the interior of the ferrule. It is not necessary to place this drop deep inside of the ferrule as in some current techniques. Further, because the magnet is placed into the ferrule after the application of adhesive (see below), the total amount of adhesive may be applied in a single (relatively larger) drop than that used for some existing designs, and can be placed anywhere along the interior of the ferrule. This also permits the use of a more viscous adhesive because application of the magnet, rather than the adhesive's viscosity and gravity, causes the adhesive to spread. Still further, because excess adhesive can ooze from the small opening of the ferrule and be wiped away (see below), the amount of adhesive applied is subject to greater tolerances. This all can simplify and ease the manufacturing and assembly process.

The magnet (in the correct polarity orientation) is then inserted <NUM> into the large opening of the ferrule as far as possible until it hits the natural stop/shoulder inside the ferrule. Inserting the magnet after applying the adhesive causes the magnet to act as a piston that pushes the adhesive throughout the inside of the ferrule and around the knot and magnet, thereby helping to ensure appropriate adhesive coverage.

Finally, any adhesive that escapes through the small opening of the ferrule can be wiped away and cleaned <NUM> from the ferrule.

Claim 1:
A suture (<NUM>) comprising:
a ferrule (<NUM>) having a small opening (<NUM>) at an end of a tapered region (<NUM>), and having a large opening (<NUM>) at an end of a straight region (<NUM>), wherein the small opening (<NUM>) is at an opposite end of the ferrule (<NUM>) than the large opening (<NUM>) and a portion of the tapered region (<NUM>) has an inner diameter that is tapered toward the small opening (<NUM>), and an inner diameter of the small opening (<NUM>) is substantially equal to an outer diameter of the suture (<NUM>); and
a suture (<NUM>) extending from the small opening (<NUM>);
characterized in that the suture is a magnetic suture and further comprises
a magnet (<NUM>) at least partially within the straight region (<NUM>),
wherein at the end of the straight region (<NUM>) and opposite the large opening (<NUM>), the ferrule (<NUM>) has a shoulder (<NUM>) where the inner diameter of the ferrule (<NUM>) begins to decrease in the tapered region (<NUM>) and the shoulder (<NUM>) prevents the magnet (<NUM>) from being inserted into the tapered region (<NUM>).