One thing baby boomers have in common is the need for joint replacements. The number of hip and knee replacements in the U.S. is approaching one million per year. Over the years ahead, projections indicate there may not be enough surgeons to handle the rapidly growing demand. In many cases, the need for the replacement comes from overuse, injury, or osteoarthritis that led to destruction of cartilage, the flexible connective tissue in hip, shoulder, and knee joints. The common phrase uttered by those facing the joint replacement is “I am down to bone on bone”. All this may change with the development of artificial cartilage according to a story in Science Daily (see Engineers make strides toward artificial cartilage).
According to the Journal of Advanced Functional Materials, researchers at Duke University found a way to create artificial replacement tissue that mimics both the strength and suppleness of native cartilage. Native cartilage is smooth and “cushiony”, yet strong and load-bearing. The idea of artificial cartilage is not new, but being able to match the features of the real thing has proven extremely challenging. The concept of artificial cartilage begins with a “scaffold” made from a three-dimensional fabric. Stem cells are then injected into the scaffold and they then grow into articular cartilage tissue. The fabric is constructed from minuscule woven fibers, with each of the scaffold’s seven layers being about the thickness of a human hair.
The toughest challenge has been to develop a material to fill the spaces in between the stem cells — not too hard, not too soft. Xuanhe Zhao, assistant professor of mechanical engineering and materials science at Duke developed the idea of a water-based polymer gel (hydrogel), and collaborated with a team from Harvard University to develop the advanced material. Zhao said It’s extremely tough, flexible and formable, yet highly lubricating. It has all the mechanical properties of native cartilage and can withstand wear and tear without fracturing.”
Hopefully, the new material will be available in the not too distant future. Engineering used to be about designing and building bridges and other large structures. Today, electrical, mechanical, and bio engineers are working with physicians to bring nano-sized structures to our bodies.