Researchers from Duke University have used a $300 3D printer together with a special hydrogel material to create life-like knee implants. The group has attempted to address the large number of meniscus knee injuries that are notoriously difficult to treat.
Damage to the meniscus cartilage is the most common knee injury in the United States and the Duke researchers explains that 500,000 cases of the injury are reported annually in the country. According to lead author, Benjamin Wiley, with this research they have “made it very easy now for anyone to print something that is pretty close in its mechanical properties to cartilage, in a relatively simple and inexpensive process.”
Despite its prevalence, the injury is difficult to treat with few options for surgical implantation. Plastic implants are often used as menisci cartilage replacements, however the strong shock-absorbing qualities of the menisci are hard to replicate. Particularly in mimicking the durability of the cartilage structures to withstand years of exertion. Benjamin Wiley, who is Associate Professor in the Department of Chemistry at Duke University explains that,
The current gels that are available are really not as strong as human tissues, and generally, when they come out of a printer nozzle they don’t stay put — they will run all over the place, because they are mostly water,
Double-network of hydrogel
To approach this common problem with a 3D printed solution, the team combined two different types of hydrogels with contrasting properties, one flexible and soft, and one stiff and strong. This double-network of hydrogel is then woven together which thereby creates a structure with great strength. To make the material 3D printable, a nanoparticle clay was added that made the hydrogel flow like liquid when extruded and set as solid when not in motion.
The technique is similar to a new innovative method developed by the Lawrence Livermore National Laboratory for 3D printing semi-solid metal.
The Duke University researchers explain that this 3D printing technique provides better function to its current counterparts and in addition allows for custom fitted implants.
Global pharmaceutical company Johnson & Johnson is also exploring the use of a 3D printed treatment for the meniscus cartilage through their DePuy Synthes arm. DePuy Synthes has partnered with bioprinting company Aspect Biosystems to use their Lab-on-a-Printer technology. DePuy Synthes has also now just acquired 3D printing technology from Michigan-based Tissue Regeneration Systems to create bone implants.
3D printing is enabling researchers and commercial companies alike to approach common medical problems with new solutions. Wiley hopes that their research will demonstrate “the ease with which this can be done will help get a lot of other people interested in making more realistic printable hydrogels with mechanical properties that are even closer to human tissue.”
The paper, ‘3D Printing of a Double Network Hydrogel with a Compression Strength and Elastic Modulus Greater than those of Cartilages’, is published in the ACS Biomaterials Science and Engineering. Authored by Duke University’s Feichen Yang, Vaibhav Tadepalli, and Benjamin J. Wiley.
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Featured image shows the hydrogel 3D printed menisci implants. Photo via Duke Today.