New research from the University of North Carolina at Chapel Hill indicates that treatment with anabolic steroids may improve surgical repair of massive or recurrent tears of the shoulder's rotator cuff tendons.
Such injuries extend well beyond the world of high-performance athletes, professional and collegiate – often occurring among older weekend athletes, including tennis and golf players. The study, which appears in the June issue of the American Journal of Sports Medicine, was led by Dr. Spero Karas, assistant professor of orthopedic surgery in UNC's School of Medicine.
Dr. Albert J. Banes, professor of orthopedics and biomedical engineering at UNC, developed a bioengineered tendon that figured prominently in the study's experiments. Through a company he founded 18 years ago, Banes developed a special tissue plate in which cells in a liquid collagen gel could remodel on their own to form a tissue-like matrix or structure. The structure then could be placed under mechanical load by a computer-driven pressure-controlled system.
In 2002, his laboratory announced it had successfully bioengineered a rhythmically beating experimental model of heart muscle.
Anabolic steroids benefit millions of people a year, said Karas, including those with deficiencies in sex hormones and burn victims who need to build up their metabolism to repair musculoskeletal tissue. They also are FDA-approved for treating anemia for their ability to help the body rebuild blood.
As it's widely known that anabolic steroids can build muscle mass and strength, Karas said he thought these properties might apply to shoulder tissue and that Banes' bioartificial tendon might provide the appropriate model for testing.
"In this new study, supraspinatus tendon cells were harvested from my patients during rotator cuff surgery, isolated and then sent to Albert's lab," Karas said. "The cells were then grown in his culture media to coalesce and form this experimental tendon model, the bioartificial tendon."
Prior to applying mechanical strain, the researchers treated some of the developing tissue with the anabolic steroid nandrolone decoanate. The steroid was administered directly into the lab dish via pipette, or dropper.
"We clearly found that when you looked at the bioartificial tendon matrices that were treated with anabolic steroid and then mechanical load or strain, we saw significant increases in their biomechanical properties," Karas said.
"The tendons were smaller, more dense, stronger, more elastic and had better remodeling properties than tissue cells not treated with steroid or placed under strain," he said. "They responded better to the load and formed a more normal appearing tendon, versus a more disorganized matrix we see in the untreated bioartificial tendon."
Thus, said Karas, it appeared that load and anabolic steroid "act synergistically" to improve the characteristics of tendon.