Barbed suture

Surgical sutures are one of the most commonly used devices for wound closure and tissue approximation. In the US, approximately 50 million open surgical procedures a year are performed requiring the use of sutures. Although effective at wound closure, one of the greatest limitations of using sutures is the reliance on the surgeon’s ability to tie secure knots. If this is done improperly, it could lead to knot breakage, slippage and potentially re-opening of the wound or dehiscence. Furthermore, the use of knots can impede would healing, restrict blood flow, increase scar formation, and distort tissue. Improvements in suture technology has allowed for a new barbed suture design to help alleviate some of these problems. The novel knotless suture has bi-directional barbs introduced in an absorbable monofilament suture using micro machining techniques.

Conventional sutures must be knotted in order to close a wound. This is the site at which sutures fail most since local stress weakens the suture fiber. The US Pharmacopeia (USP) has thus specified minimum knot-pull tensile strength requirements for sutures. This requires extensive training since the manner in which knots are placed and excessive wound tension can result in various complications. Some of the potential difficulties with conventional suture knots include:

• Knot untying and/or breaking – Knots can become untied and fail if the suture material is slippery. In addition, knots can split or break if it is tied improperly or if it is damaged by surgical tools.

• Suture extrusion – Suture knots may erupt through the wound if it is left below the skin. This is due to the bulk size of suture knots which could cause patient discomfort, infection, and inflammation. This is called “spitting” and the rate of its occurrence may be as high as 5%.

• Infection – Spaces between the filaments of a braided suture and the interstices within a suture knot have been shown to harbour bacteria.

• Rupture, or splitting open of a surgical wound – Closure failure at the site of tightly approximated wounds is primarily caused by tissue pull-through. Suture loops in disrupted wounds may be found intact up to 88% at the time of disruption.

• Reduced inflammation – Wound closure strength can be reduced up to 77% due to excessive tension. Wounds that are closed under strong tension have shown to exhibit an inflammatory response, releasing neutrophilic cell infiltrate and increasing tissue myeloperoxidase activity.

• Ischemia and scarring – Sutures that are overly taut can produce pressure necrosis. Microangiographic examinations have showed that tightly tied sutures caused avascularity within the tissue and the area surrounding the suture loops. The resulting microinfarction leads to increased scarring in addition to compromising the wound closure strength.

Currently, there is only one barbed suture approved and marketed in the U.S. The barbed suture produced by Angiotech Pharmaceuticals, Inc. is marketed under the name Quill SRS (Self Retaining System) barbed sutures.