Marino and co-workers investigated the biological properties and clinical applications of thin carbon fibers. In studies of laboratory animals, they showed that the fibers were better tolerated by the body than other man-made materials used in surgical implants, and that the basic reaction of the body to each fiber was the formation of concentric layers of connective tissue and cells that extended along the entire length of each fiber.

Marino and co-workers used bundles of 40,000 fibers to treat patients who had injured knee ligaments. When bundles were implanted inside the ligaments and attached at each end to bone, the patients returned to pre-injury levels of occupational activity sooner and more often, compared with patients who received standard clinical treatment.

In an FDA-approved prospective study of patients who had multiple knee-ligament injuries conducted at three university and military hospitals, the safety and efficacy of carbon fibers for the repair of injured knee ligaments was confirmed.

Bundles of carbon fibers implanted inside the injured tendons of thoroughbred race horses strengthened the tendons by stimulating the growth of new connective tissue inside the tendon. Horses treated with carbon fibers returned to racing earlier and more frequently, compared with horses that received standard clinical treatment.