TUESDAY, March 30 (HealthDayNews) -- The University of Pittsburgh is leading an international trial to study the effect of calcium hydroxylapatite (CaHA) injections in people with vocal cord paralysis.

The trial, at 15 international sites, is the largest such study in the field of vocal disorders. Patients taking part in the trial will be given injections of CaHA into their injured vocal cords.

The effectiveness of the injections will be measured during follow-up visits after one, three, six and 12 months.

"In this study, we are trying to determine the long-term efficacy and utility of CaHA as an injection material to treat vocal fold disorders," Dr. Clark Rosen, director of the University of Pittsburgh Voice Center, says in a prepared statement.

"Current injection materials have limitations in terms of their effectiveness and longevity; there are concerns with some of the substances being reabsorbed and other materials triggering a rejection response to the material. It is hoped that the CaHA injection material will be an improvement over presently available substances," Rosen says.

The study is sponsored with an educational grant from BioForm Medical Inc., which manufactures CaHA injections.

More information

The U.S. National Institute on Deafness and Other Communication Disorders has more about vocal cord paralysis.