3D printing improves accuracy, personalization of prosthetic implants

Researchers have developed accurate, personalized prosthetic implants for the middle ear using CT scans and 3D printing, according to a study presented at the annual Radiological Society of North America (RSNA) meeting.

Currently, treating patients with conductive hearing loss involves surgical reconstruction using prostheses made from steel and ceramic cups. However, this treatment method has a high rate of failure due to the lack of personalization in the implants. In this study, researchers test the effectiveness of implants developed using CT scans and 3D printing.

"The ossicles are very small structures, and one reason the surgery has a high failure rate is thought to be due to incorrect sizing of the prostheses," said study author Jeffrey D. Hirsch, MD, assistant professor of radiology at the University of Maryland School of Medicine (UMSOM) in Baltimore. "If you could custom-design a prosthesis with a more exact fit, then the procedure should have a higher rate of success."

Researchers started by removing the middle linking ossicular chain bone from three cadavers and imaged the structure using CT scans. The scans where then used to recreate a 3D printed prosthesis fitting each ear. Following the experimentation, four surgeons were tasked with inserting the prosthesis into the middle ear of the cadaver to test the implant's accuracy in fitting to the original bone's place. Results showed all four surgeons were able to correctly place the prothesis in its intended bone.

"This study highlights the core strength of 3D printing—the ability to very accurately reproduce anatomic relationships in space to a sub-millimeter level. With these models, it's almost a snap fit,” concluded Dr. Hirsch. “The results suggest that commercially available CT scanners can detect significant anatomic differences in normal human middle ear ossicles, and that these differences can be accurately represented with current 3D printing technology. More significantly, surgeons can detect these differences, which should not only increase the likelihood of a proper fit, but also decrease surgical time.”