Customized 3D-printed middle ear prosthetics can improve the accuracy of surgical intervention in patients with conductive hearing loss, according to a study presented at the annual meeting of the Radiological Society of North America (RSNA) in Chicago, Ill.
Conductive hearing loss results from damage to the ossicles — tiny bones in the middle ear — and is often caused by trauma or infection. Physicians typically treat this type of hearing loss by implanting prostheses made of stainless steel struts and ceramic cups in a procedure that may prove ineffective.
"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 Dr. Jeffrey Hirsch, assistant professor of radiology at the University of Maryland School of Medicine. "If you could custom design a prosthesis with a more exact fit, then the procedure should have a higher rate of success."
To improve implant design and function, the researchers extracted the middle ossicle from three cadavers, scanned the structures with CT, and created 3D-printed prostheses based on the scans. The devices were made from a resin that hardens when exposed to ultraviolet laser light. Each of the prostheses had unique measurements.
Four surgeons then surgically inserted the 3D-printed models into the cadavers without prior knowledge of which cadaver was the source of the model. All of the surgeons chose the correct match for each 3D-printed prosthetic.
"This study highlights the core strength of 3D printing — the ability to very accurately reproduce anatomic relationships in space to a submillimeter level," Hirsch said. "With these models, it's almost a snap fit."
Using 3D printing in a clinical setting would allow physicians to tailor hearing implants to patients before surgery, rather than the standard method of adjusting during surgery, thus decreasing surgical time,.
The researchers plan to add stems cells to 3D-printed middle ear prostheses, which would allow them to become permanently fixed to bone structure.