As we age, our lifestyle and history of injuries can catch up to us.
Each year, more than a million Americans receive total knee or hip replacements, according to data from the American Academy of Orthopedic Surgeons, and the average age of patients undergoing this treatment is getting younger.
“Because today’s population is more active and there are more sports-related injuries, younger and younger people need these replacement surgeries,” Susmita Bose, professor in the School of Mechanical and Materials Engineering at Washington State University, says. “But if you get your first surgery in your 40s or 50s, and then after one revision surgery, the second revision surgery may not be possible since the bone is compromised, and the patient may be wheelchair-bound.”
For over a decade, Bose, along with Amit Bandyopadhyay, has been researching ways to use 3D printers to make joint replacements heal better, and last longer.
While implants are classically made of metals, plastics, or ceramics, these inorganic materials alone don’t bond well with surrounding bone and tissues. This can potentially cause loosening of the implant over time, and eventually bring about the same pain and discomfort that the original surgery was supposed to alleviate.
Most implants last for about 10 to 15 years, though some can fail as soon as 7 years. During a replacement surgery, a new implant is inserted, and the surrounding bone may also need to be stabilized, with calcium phosphate coating, a bone like material to improve implant biocompatibility.
To tackle this, Bose and her team developed a bone-like material made mostly of chemistry-modified calcium phosphate, with additives and natural medicinal compounds, that act as a scaffold for new tissue to grow within 3D printed structures. In small injuries, the material can be absorbed by the body, allowing it to repair itself.
“With chemistry-modified calcium phosphate coating surrounding the metal, the bone tissue can grab it better and stabilize the implant further,” Bose says. This makes it less likely for patients to need revision surgery.
Meanwhile, Arda Gozen, George and Joan Berry associate professor in the School of Mechanical and Materials Engineering, and his team are working toward something a bit more difficult: printing articular cartilage for knee joints.
“Cartilage is such a finnicky tissue. When it fails, it fails bad,” Gozen says. “Realistically, we are still a ways away. But, along with some other critical tissues, this research would have a huge impact on quality of life.”
Articular cartilage is what allows joints to glide smoothly. It wears down over time, causing osteoarthritis—the most common arthritis disorder, which affects millions of people throughout the world—and with it, chronic pain.
“It’s not really rocket science anymore to take a number of cells and turn it into something larger,” Gozen says. “You can make living blobs. But making them work with the human body requires quite a bit of engineering, effort, and science.”