January 2019

UA Researchers Study How to Regrow Long Bone Segments Using 3D Printing

John A. Szivek, PhD, a scientist at the University of Arizona (UA) College of Medicine – Tucson, has received a $2 million grant from the U.S. Department of Defense to launch a study to determine how to heal bone fractures using a combination of 3D printing and adult stem cells.

“Imagine an impact that causes half of a long bone to shatter so that it can’t be put back together — no current surgical treatment can ensure that kind of injury will heal,” explained Szivek. Current treatment of these traumatic injuries usually fails and requires repeated surgeries, sometimes leading to amputation. “There’s just no good way of regenerating or re-growing long bone segments right now.” The human body will attempt to re-grow missing or damaged bone for a few months after an injury, but it eventually gives up on the process. At that point, scar tissue fills the defect instead of bone. “That’s why we need to develop a way … to help the body while it is still able to grow and replace the bone,” Szivek said.

Szivek’s lab, along with clinical partners in the UA Department of Orthopaedic Surgery, plans to 3D print plastic bone-shaped frames that can replace large, missing,  or broken bone segments. These scaffolds will be filled with calcium particles and adult stem cells, two key elements that lead to much faster healing and bone growth. Once implanted, the scaffold will serve as a template for the bone to grow on. Pilot studies have shown this technique works well. “We achieved complete bone formation, covering a large bone defect in about three months. Now we want to make that healing process even faster,” said Szivek.

The team will also test whether exercise early in the healing process can help speed up healing and recovery. To test this, the 3D implants will be embedded with tiny sensors that can wirelessly transmit exercise activity. These sensors will analyze how much weight is being put on the scaffold and for what length of time. Bone size changes in an active group that regularly exercises will be compared with an inactive group. Szivek’s team expects to see that the active group that regularly put weight on their healing limbs will show quicker bone growth. His team hopes to develop guidelines for post-surgical physical therapy by demonstrating that exercise leads to better bone formation. If the study is successful, Szivek anticipates the clinical trials will take place in military personnel.

Szivek hopes the potential therapy also will help patients who have had bones surgically removed due to cancer.

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