steroids are known to build muscle mass and boost strength, so Karas and his colleagues set out to see whether steroids might improve rotator cuff healing. The research involved bioengineered tendons developed by co-author Dr. Albert J. Banes. The researchers collected tendon samples from six people who were having rotator cuff surgery. Cells from these tendons were isolated and used to grow the bioengineered tendons.
Some of these tendons were treated with the anabolic steroid nandrolone decanoate, while others were not. Some tendons were also subjected to load testing, in which the tendons were stretched. Tendons that had been treated with steroids and subjected to loading were stronger, denser and more elastic than other tendons, the researchers report in the American Journal of Sports Medicine. The steroid-treated tendons also had a more natural appearance than other tendons.