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.
Karas said the research had clinical applications, including the possibility of a day when bioartificial tendon matrices might literally help bridge the gap between deficient human tissue and the normal state – that is, to bridge the holes that remain following surgery for large rotator cuff tears.
In the less distant future, the new study's crucial implications may apply to the post-surgery healing of tendons that have been torn or retracted for a long time, he said.
"Orthopedic surgeons, especially those who specialize in the shoulder, tend to have one vexing dilemma in front of them: There are certain states that make rotator cuff repair extremely difficult, and that would be a tendon that has experienced atrophy and degeneration, that has been torn for a long time. In other words, not a fresh tear.
"With FDA-approved drugs taken at the appropriate dosages for the appropriate occasions, we might be able to modulate tendon-to-bone healing in this postoperative period," he said, adding that the next step is to explore the use of anabolic steroids in the animal model.
Most of these patients are between 50 and 70 years of age and have their athletic years behind them. But many are very active and comprise a much larger demographic in society than the athlete, Karas said.
"And these weekend warriors who play tennis and golf are represented far more in most orthopedic practices than professional or collegiate athletes." Support for the study came from the National Institutes of Health.