Public Release: 

Boston Children's Hospital announces results of Bridge-Enhanced® ACL repair study

The first-in-human study shows BEAR® procedure has similar outcomes to traditional reconstruction

Boston Children's Hospital

BOSTON (March 12, 2019) - Today researchers at Boston Children's Hospital announce encouraging Phase I results from a first-of-its-kind study - repairing ACL tears by helping the ligament regrow itself. The results will be presented at the Arthroscopy Association of North America (AANA)/American Orthopaedic Society for Sports Medicine (AOSSM) 2019 Specialty Day on March 16.

In this small, first-in-human study, the team, led by Boston Children's orthopedic surgeons Martha Murray, MD, and Lyle Micheli, MD, got new ACL tissue to form in all 10 experimental trial participants using a procedure called Bridge-Enhanced ACL Repair (BEAR) ®.

"We wanted to find a way to encourage the ACL to heal itself," says Murray, who invented the procedure. "We hoped we could find a better way than removing the torn ACL and replacing it with perfectly normal tissue from somewhere else, so we started working on a protein-based scaffold."

After decades of laboratory research, the FDA approved a human trial for the BEAR procedure that assessed the safety and early efficacy of the implant used to encourage tissue growth. Of the 20 patients who participated, 10 underwent the BEAR procedure and 10 served as the control group, receiving the standard ACL reconstruction procedure which involves grafting in a piece of tendon taken from elsewhere in the body.

The BEAR implant is a proprietary bio-engineered sponge and is designed as a bridging scaffold to facilitate healing of the torn ACL. The scaffold is surgically placed between the torn ends of the ACL and some of the patient's own blood is then injected into it. The scaffold soaks up and holds the blood to stimulate healing of the torn ACL.

"At 24 months, nine of the ten repaired subjects and seven of the ten reconstructed patients completed a study visit," says Lyle Micheli, director of the Boston Children's Division of Sports Medicine and lead surgeon on the trial. "There were no graft or repair failures and recovery was similar for both groups, providing us with encouraging outcomes and an exciting road ahead."

Since the completion of the first phase, the team has moved forward with additional phases of the research. The second was a randomized, blinded study of 100 patients, again comparing BEAR procedure with standard reconstruction. A third study will look further at the effects of age on the outcomes of this novel technique

ACL Reconstruction Facts

  • Every year approximately 200,000 ACL injuries occur, making ACL surgery one of the most common orthopedic procedures in the United States.
  • Although most patients are able to return to sports, the ACL re-tear rate hovers near 20 percent.
  • Up to 80 percent of patients develop arthritis 15 to 20 years after surgery.


This study is funded by the Translational Research Program at Boston Children's Hospital, the Children's Hospital Orthopaedic Surgery Foundation, the Children's Hospital Sports Medicine Foundation and the National Institutes of Health (grant # AR065462) and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (grant #R01AR056834.) This research was also conducted with support from the Football Players Health Study at Harvard University which is funded by a grant from the National Football League Players Association.

Dr. Murray is founder of Miach Orthopaedics, a privately held company dedicated to developing bio-engineered surgical implants for connective tissue repair which has recently licensed the BEAR technology. Dr. Murray and certain members of the research team have equity in and or receive compensation for serving as either an advisor or employee of Miach Orthopaedics.

Boston Children's Hospital is also an equity holder in Miach Orthopaedics. Dr. Murray, other members of the research team, and Boston Children's Hospital may gain financial benefits if the technology being studied in this trial proves to be of benefit. As in all research studies, the Hospital has taken, and will continue to take, all necessary steps to ensure research subject safety, and the validity and integrity of the information obtained by this research.

About Boston Children's Hospital

Boston Children's Hospital is home to the world's largest research enterprise based at a pediatric medical center, where its discoveries have benefited both children and adults since 1869. More than 1,100 scientists, including seven members of the National Academy of Sciences, 11 members of the Institute of Medicine and 10 members of the Howard Hughes Medical Institute comprise Boston Children's research community. Founded as a 20-bed hospital for children, Boston Children's today is a 404-bed comprehensive center for pediatric and adolescent health care. Boston Children's is also the primary pediatric teaching affiliate of Harvard Medical School. For more, visit our Vector and Thriving blogs and follow us on our social media channels: @BostonChildrens, @BCH_Innovation, Facebook and YouTube.

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