Arthroscopy is a minimally invasive surgical procedure that allows the interior of a joint to be examined or repaired. A primary purpose of arthroscopic surgery, as compared with more invasive procedures, is to reduce the stress on recovering patients. In the process, however, a great deal of stress is placed on the sutures used to hold soft tissues together. Aware of dissatisfaction among some surgeons with the performance of braided-polyester sutures in arthroscopic settings, DePuy Mitek Inc. (Raynham, MA; www.jnjgateway.com) sought to develop a suture possessing better strength than braided polyester and minimal thickness.
Dyneema Purity is the first UHMWPE fiber produced specifically for medical devices.
High-strength sutures play a critical role in arthroscopic procedures. In contrast to open surgery, the sutures used in arthroscopy must allow for a series of knots to slide down the suture, through the small incision, and around difficult angles without the suture fracturing or breaking. Therefore, the suture needs to be easy to handle, to have excellent tensile and breaking strength, and to allow for pinpoint placement of tight knots in confined joint spaces. Given the space restrictions, particularly inside the joint capsule, the bulk of a suture’s knots must not abrade the repaired soft tissues.
For DePuy Mitek, a recently developed material from DSM Dyneema (Heerlen, Netherlands; www.dsm.com) was the right fit for its suture project. In response to requests from customers, DSM Dyneema had developed an ultrahigh molecular weight polyethylene (UHMWPE) fiber suitable for a variety of medical applications. The result, called Dyneema Purity, is the first UHMWPE fiber produced specifically for medical devices, according to the company.
“We found that Dyneema Purity was the best choice for increasing the tensile strength of our new sutures,” says Chuck Pearlman, director of marketing at DePuy Mitek. “When we combined it with our proprietary technology, we were able to develop a product that features both high strength and excellent handling characteristics.”
From conception to product launch, the companies collaborated in product development, quality control, and regulatory compliance. The resulting sutures can provide more strength than polyester at the same diameter. “This is critical to the success of arthroscopic procedures,” says Carina Snijder, medical business manager at DSM Dyneema. “The tensile strength is important not only during the surgery when a break can be frustrating for the surgeon, but also afterwards when it could affect a patient’s recovery.”
An orthopedic suture made with the Purity material can be about half the thickness of a polyester suture of equal strength. The thinner suture diameter leads to smaller knots and the potential reduction of abrasion of adjoining tissues, thereby maximizing patient comfort.
The sutures are currently available and have been adopted by some surgeons. Their reactions have been as positive as that of Rick Angelo, orthopedic surgeon at the University of Washington, according to the companies.
“The strength of these sutures is great and the material seems a bit more flexible,” Angelo says. “Knots tie easier and compress more readily. They are also softer and less stiff.”