Spongy Implant May Fix ACL Tears

To get patients back on the court or the field more quickly

That popping sound brings even the strongest athletes to their knees. Damage to the anterior cruciate ligament, or ACL, the ligament at the knee that holds together the upper and lower leg bones, can be a painful and debilitating injury for athletes and non-athletes alike, leading to further tears and arthritis over the long term.

ACLs can't heal themselves or be stitched back together, so every year, surgeons perform 100,000 ACL reconstruction surgeries in which they replace a patient's ACL with a tendon removed from the hamstring. But what if ACLs could repair themselves? Doctors at Boston Children's Hospital have been working on a treatment called Bridge-Enhanced ACL Repair (BEAR) that can do just that. Today they announced the encouraging results of their first clinical trial.

The BEAR treatment links the two broken parts of the ACL with a spongy, protein-coated scaffold filled with the patient’s blood to reduce the chance of rejection. Over time, the ACL will regrow and connect through the bridge. The advantage of the BEAR treatment is that it doesn’t require a second surgery on the arm for the tendon graft, and that it preserves much more of the patient’s original ACL tissue, which may decrease the likelihood of further damage.

In this first study, the researchers implanted the BEAR device in 10 patients between ages 18 and 35 who had torn their ACLs no more than a month prior. They also needed to have a few millimeters of tendon dangling so that the device could be attached. Ten other patients who fell into the same criteria received the standard ACL reconstruction surgery. In the months after the surgery, patients in both groups recovered at about the same rate. But those who received the BEAR treatment regained hamstring strength more quickly—a process that can often take weeks or months, as the Wall Street Journal reports—and showed no signs of infection or knee stiffness. A year later, the researchers were surprised by how much all 10 patients had healed.

The real test will be how the patients' tendons hold up in the long-term; in the past, other ACL procedures have seemed promising only to cause knee problems for patients just five years later, according to the New York Times.

Still, the researchers are encouraged by results of this trial. Next they'll test the treatment in 100 patients with similar inclusion requirements. They hope to start enrolling patients in the experiment this summer, according to the Boston Globe.