1. Field of the Invention
The invention relates to a method of barbing suture filament by varying the blade geometry and/or the movement of a blade when cutting a suture filament where the method can also be utilized to cut a plurality of axially spaced barbs on the exterior of sutures and an apparatus for performing this.
2. Description of the Prior Art
In the prior art, it is well known that surgical and traumatic wounds are typically closed with a filament introduced into the tissue by a needle attached to one end. Closure of the wound and holding tissues together supports healing and re-growth. What is typically used for this procedure is known as a suture.
A barbed suture is a one-way suture which allows passage of a needle-drawn suture in one direction through tissue, but not in the opposite direction. A barbed suture is generally an elongated body having a pointed leading end and a plurality of axially and circumferentially spaced barbs on the exterior surface of the elongated body.
In closing a wound with a barbed suture, the suture is passed through tissue at each of the opposed sides of a wound. Suture pairs are formed in which trailing ends of sutures are positioned generally in alignment at opposite sides of the wound. On insertion of each suture, the needle is pushed to extend out of the tissue at a point laterally remote from the wound, then the needle is pulled out to draw the suture to the desired position, and the suture is then severed from the needle. (Note that methods of using barbed sutures are disclosed in copending U.S. patent application Ser. No. 09/896,455, filed Jun. 29, 2001, entitled “Suture Method” and assigned to Quill Medical, Inc., the disclosure of which is incorporated herein by reference.) The advantage of using barbed sutures is that there is an ability to put tension in the tissue with the result of less slippage of the suture in the wound. The number of suture pairs is selected in accordance with the size of the wound and the strength required to hold the wound closed. Although tissue anchoring is easier done with a very pointed barb and a relatively skinny tip, better tissue holding results are obtained with a fuller tip barb.
In some circumstances of tissue repair, a random configuration of barbs on the exterior of the suture might be preferred. With as many barb angles as possible, superior wound holding would be achieved. However, in other circumstances where the wound or tissue repair needed is small, a small suture would be preferable. A small suture would require a reduced number of barbs on the exterior of the suture. Various methods of cutting the barbs have been proposed (see e.g. U.S. Pat. No. 5,931,855). However, such methods have not been commercially exploited for reasons which are unclear.
It is seen from the foregoing that there is a need for a method of cutting barbs on the exterior of sutures with a minimum of difficulty and in a reliable and relatively economic fashion so as to allow for the wide spread commercialization of such sutures. Such a method should also be able to vary the size of the barbs, their location and depth to allow for variation thereof and versatility of their application. The method should be able to cut a plurality of barbs with the positioning depending on the number of barbs needed. The need also exists for a device able to use the method described above which can provide a plurality of axially spaced barbs either in a random or similar configuration, with the configuration depending upon, among other things, the type of tissue being repaired.