Injecting a patient's bone marrow stem cells into the shoulder during rotator cuff surgery can significantly improve healing and tendon durability, according to a new study.

In findings presented today at a meeting of the American Academy of Orthopedic Surgeons, French researchers said the technique not only helped speed healing of the rotator cuff tendons, but also prevented further tears.

Lead researcher Philippe Hernigou, M.D., an orthopedic surgeon at the University of Paris, said “retears” are common after shoulder surgery — often requiring additional procedures. But the new stem cell technique significantly reduces that risk.

"Many patients undergoing rotator cuff repair surgery show advanced degeneration of the tendons, which are thinner and atrophic (more likely to degenerate), probably explaining why negative results are so often reported in the literature, with frequent post-operative complications, especially retear,” he noted.

"These retears were more frequently associated with the [conventional surgery] patients who were not treated with [stem cells].”

More than 2 million Americans have rotator cuff surgery each year to re-attach their shoulder tendon to the head of the upper arm bone. Rotator cuff tears can occur during a fall or when lifting an extremely heavy object, but most are the result of aging and overuse.

The French study, published in the journal International Orthopedics, included 90 patients — half of whom underwent conventional surgery and half of whom received injections of bone marrow concentrate and stem cells.

After six months, all 45 of the patients who received stem cells had healed rotator cuff tendons, compared to 30 (67 percent) of the patients who did not receive them. After 10 years, intact rotator cuffs were found in 39 (87 percent) of the stem cell patients, but just 20 (44 percent) of those who underwent conventional surgery.