3-D-printed prosthetic implants could improve treatment for hearing loss

December 1, 2017
Size comparison between 3-D printed prosthesis implant and a penny. Credit: Radiological Society of North America

Researchers using CT scans and 3-D printing have created accurate, custom-designed prosthetic replacements for damaged parts of the middle ear, according to a study being presented today at the annual meeting of the Radiological Society of North America (RSNA). The technique has the potential to improve a surgical procedure that often fails because of incorrectly sized prosthetic implants, researchers said.

Hearing works partly through the transmission of vibrations from the ear drum to the cochlea, the sensory organ of hearing, via three tiny bones in the middle ear known as ossicles. Ossicular conductive hearing loss occurs when the ossicles are damaged, such as from trauma or infection.

Conductive hearing loss can be treated through surgical reconstruction using prostheses made from stainless steel struts and ceramic cups. The surgery, which generally involves tailoring a prosthesis for each patient in the operating room, is plagued by high failure rates.

"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, M.D., 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."

Dr. Hirsch and colleagues studied 3-D printing as a way to create customized prostheses for patients with conductive hearing loss. The technology has been used successfully to solve a number of other medical prosthesis problems, including in the areas of joint replacement and facial reconstruction surgery.

The researchers removed the middle linking bone in the ossicular chain from three human cadavers and imaged the structures with CT. They employed an inexpensive 3-D printer to create prostheses to restore continuity for each of the middle . The prostheses were made from a resin that hardens when exposed to ultraviolet laser light. Each of the prostheses had unique measurements.

3-D printed prosthesis implant. Credit: Radiological Society of North America

Four surgeons then performed insertion of each prosthesis into each middle ear, blinded to the bone from and for which each was designed. The researchers then asked the surgeons to match each prosthesis to its correct source.

All four surgeons were able to correctly match the prosthesis model to its intended temporal bone—the bone containing the middle and inner parts of the ear. The chances of this occurring randomly are 1 in 1,296, according to Dr. Hirsch.

"This study highlights the core strength of 3-D printing—the ability to very accurately reproduce anatomic relationships in space to a sub-millimeter level," Dr. Hirsch said. "With these models, it's almost a snap fit."

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 3-D printing technology. More significantly, surgeons are able to detect these differences, which should not only increase the likelihood of a proper fit, but also decrease surgical time, according to Dr. Hirsch.

The next step in the research, Dr. Hirsch said, is to create prostheses out of biocompatible materials. The researchers are also looking at a different approach that would combine the 3-D-printed with .

"Instead of making the prosthesis solid, you could perforate it to be a lattice that allows stem cells to grow onto it," Dr. Hirsch said. "The stem cells would mature into bone and become a permanent fix for patients with hearing loss."

Explore further: Bacterial biofilms identified in ocular prosthesis

Related Stories

Bacterial biofilms identified in ocular prosthesis

August 5, 2015
(HealthDay)—Bacterial biofilms are associated with ocular prostheses, according to a letter to the editor published in the August issue of Clinical & Experimental Ophthalmology.

Mechanical heart valve prosthesis superior to biological

November 12, 2015
A mechanical valve prosthesis has a better survival record than a biological valve prosthesis, according to a large registry study from Sweden's Karolinska Institutet. The finding, which is published in the European Heart ...

Development of prosthetic hands stagnated for 20 years: study

June 12, 2012
The development of body-powered prosthetic hands has stagnated for over twenty years. That is the main conclusion of a study by researchers from TU Delft and the University of Groningen into this type of prosthesis, which ...

Engineers develop a new non-invasive method to detect infections in prostheses

December 14, 2016
Engineers at the University of California San Diego have developed a new non-invasive method to detect infections in prostheses used for amputees, as well as for knee, hip and other joint replacements. The method, which is ...

Recommended for you

3-D printed microfibers could provide structure for artificially grown body parts

December 12, 2017
Much as a frame provides structural support for a house and the chassis provides strength and shape for a car, a team of Penn State engineers believe they have a way to create the structural framework for growing living tissue ...

Time of day affects severity of autoimmune disease

December 12, 2017
Insights into how the body clock and time of day influence immune responses are revealed today in a study published in leading international journal Nature Communications. Understanding the effect of the interplay between ...

Potassium is critical to circadian rhythms in human red blood cells

December 12, 2017
An innovative new study from the University of Surrey and Cambridge's MRC Laboratory of Molecular Biology, published in the prestigious journal Nature Communications, has uncovered the secrets of the circadian rhythms in ...

Team identifies DNA element that may cause rare movement disorder

December 11, 2017
A team of Massachusetts General Hospital (MGH) researchers has identified a specific genetic change that may be the cause of a rare but severe neurological disorder called X-linked dystonia parkinsonism (XDP). Occurring only ...

Protein Daple coordinates single-cell and organ-wide directionality in the inner ear

December 11, 2017
Humans inherited the capacity to hear sounds thanks to structures that evolved millions of years ago. Sensory "hair cells" in the inner ear have the amazing ability to convert sound waves into electrical signals and transmit ...

Gene therapy improves immunity in babies with 'bubble boy' disease

December 9, 2017
Early evidence suggests that gene therapy developed at St. Jude Children's Research Hospital will lead to broad protection for infants with the devastating immune disorder X-linked severe combined immunodeficiency disorder. ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.