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Low-back pain can affect almost anyone at any time. In the United States, 8–15 percent [Ranu, 1] of back injuries involve the spinal discs, which act as a cushion between each vertebra. When a human spinal disc slips or herniates, part or all of it bulges out from its usual setting between the vertebrae (Figure 1).

Man has recognized carbon as an implant material well tolerated by the body for many years. Indeed, carbon in an impure form (Indian ink) was first used in the making of tatoos. Most recently carbon has been used in a filamentous form of high strength. These carbon fibers are produced in long tows of 40,000 fibers, each with a cross sectional area of about 7μ (Figure 1), by heating acrylic fibers to high temperature. This causes the noncarbon components to be removed while maintaining the molecular structure (scaffold) of the acrylic. Fibers can be chopped into short lengths and used to reinforce polyethylenes (8, 11, 12). These reinforced plastics have-twice the strength and ten times the stiffness of their non-reinforced counterparts, but suffer only one tenth as much creep when subjected to a load (11). Long tows of carbon fibers are used in tendon and ligament replacement (1, 2, 4, 5, 6, 7, 9, 10). This application warrants further investigation because of the apparent ability of the carbon fibers to induce the formation of ligaments and tendons (3, 4, 5, 6, 7).

Skin is a viscoelastic material, whose properties modify with age, some diseases and certain therapeutic treatments.