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3D Printed Knee Implants

One subject among my weekly e-briefs which consistently generates a lot of feedback is knees. 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 roughly one million per year, 2/3 of which are knees. 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 will change with the development of artificial cartilage and 3D Printing. 

Every week, I see something new in the development of artificial cartilage. The 3D printers are quite advanced and able to print body parts. The picture at the beginning of this post, provided by Feichen Yang, a graduate student at Duke University, shows 3d-printed knee parts. The challenge is not the printer, the challenge is the “ink”. 

The most promising material is hydrogel, a colloidal gel consisting mostly of water. Yang explained two different types of hydrogels — one stiffer and stronger, and the other softer and stretchier. He called the combination a double-network hydrogel which is very strong. By changing the amounts of the two hydrogels, it is possible to fine tune the strength and elasticity of the mixture. The goal is to eventually create cartilage equal to or better than human cartilage.

The Duke researchers added an additional ingredient, a nanoparticle clay. The clay makes the hydrogel flow through print head like water, but then immediately harden into its printed shape. The process of taking a CT scan and printing the  new menisci takes about a day. In other words, hospitals will be able to do a CT scan of your knees and then print the replacement parts in-house, and have them ready the next day. 

Read the full story about what is going on at Duke here. Read more about 3D printing and regenerative medicine in Health Attitude: Unraveling and Solving the Complexities of Healthcare.

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