Improving treatment for knee injuries.

Clinical trials are under way to test a new material derived from pigs' intestines that, when inserted into the human body, may serve as a scaffold around which the body can regenerate damaged tissues, such as torn ligaments or tendons. The new material--which is, in essence, sausage casing--was developed through a partnership between Purdue University, West Lafayette, Ind., and DePuy Orthopaedics Inc., Warsaw, Ind.

The material, called SIS for small-intestinal submucosa, is derived from the middle layers of the small intestine of pigs. Once these layers of intestine are removed, they are disinfected and processed into different forms--such as tubes, sheets, or fibers--and sterilized and stored for future use. Even though the intestinal lining that gives rise to the raw material is very thin--80 to 100 microns, or about as thick as a piece of office paper--SIS is extremely strong, explains Stephen F. Badylak, director of research for Purdue's Hillenbrand Biomedical Engineering Center and head physician for the school's athletes.

Animal studies show that, once SIS is placed within a body, it appears to aid the natural healing response. "For example, when SIS is inserted into the site of a wound, there is a proliferation of new blood vessels created in the immediate area. This is very important in the wound-healing response, because the blood vessels not only nourish the graft, but they also bring to it all the molecules the body needs to rebuild the tissue."

This ability to remodel makes SIS ideal in orthopedic applications such as replacement material for damaged ligaments and tendons. Torn or damaged ligaments and tendons--the fibrous tissues that connect bone, cartilage, and muscle--make up the bulk of sports-related injuries.

"Anterior cruciate ligament knee injuries can be... career-ending... for many athletes," Badylak points out. "The surgical procedure used to treat this problem usually involves...