For decades surgeons have replaced torn anterior cruciate ligaments with tendons harvested from the kneecap or hamstring, but patients are starting to choose a new method that allows the ACL to heal in place.
Called Bridge Enhanced ACL Restoration or BEAR, the technique embeds the disconnected ends of a ruptured ligament in a kind of sponge made of collagen, a protein commonly found in connective tissue, that is soaked in the patient’s own blood.
Studies in about 200 patients used to support the procedure’s approval in late 2020 found that using this kind of healing cocoon approach yielded results equivalent to replacement, though long-term durability remains an open question.
Healing rather than replacement was an irresistible option for Jenna Richardson of Oceanside, who chose BEAR over reconstruction after tearing her ACL while mountain biking in July.
Located inside the knee joint, the ACL is critical for stability, making its repair or replacement essential for continued athletic activity. Given that Richardson is highly active, enjoying everything from snowboarding to surfing, there was no question that some sort of procedure would be necessary.
After reading every study she could find, the medical sales representative said she liked the idea of avoiding the ligament harvesting process which requires an additional incision and increases the amount of rehabilitation necessary after surgery. She also shied away from replacement with tissue from a deceased organ donor after several friends who went that route experienced additional tears.
In the end, she said, BEAR seemed like a low-risk choice given that she could always opt for reconstruction if the healing route didn’t pan out.
“I’d rather have my own ACL than anyone else’s or them harvesting another piece of my tissue and ending up having deficits there,” Richardson said.
Dr. Tim Wang, an orthopedic surgeon and sports medicine specialist at Scripps Clinic, performed the procedure on Aug. 22, making Richardson the first patient in San Diego County to undergo BEAR repair.
Fixing the ACL, he noted, is not a new idea. Repair was a common choice in the 1970s and 1980s but had a high failure rate generally attributed to the ligament’s low blood supply and location deep inside the knee joint where certain enzymes make healing difficult.
BEAR appears to offer a solution by creating what is, in essence, a large manufactured blood clot that can be placed around an ACL’s severed ends using a clever arrangement of sutures.
“The early data and research shows that it’s as good as our standard of care with a potential for faster muscle recovery,” Wang said.
As is the case with any new medical device or procedure, the question is how well gains shown in initial trials will hold up with larger numbers of patients.
“We want to confirm that it’s as good as we think it is,” Wang said.
Initially, experts said that BEAR is unlikely to become the standard of care until there is a large body of evidence that repairs are as durable as they are for replacement.
Professional athletes are likely to continue going the reconstruction route for some time to come, said Dr. Tal David, a San Diego orthopedic surgeon whose practice often includes pro athletes.
As the only other surgeon in the county approved to perform BEAR procedures, David said that it’s difficult to recommend something brand new when a person’s livelihood hangs in the balance and the existing standard yields very good results.
“We’ve done many, many thousands of reconstructions over many years, and the risk of retearing is around 5 percent,” David said. “For professional athletes, I would say it’s about a predictable outcome.”
On the other hand, there are clear advantages to repair. In addition to avoiding a harvesting procedure David said that healing in place may prove better for recovery of the nerves that allow the body to sense knee position.
“We’ll figure out pretty quickly whether or not this is something that holds up in comparison to reconstruction in high level athletes,” David said.
The rehabilitation process is also somewhat different with BEAR. Generally patients with replaced ACLs are recommended to start bending their knees within a few weeks after surgery. However, much less bending is initially recommended after a BEAR procedure as the ligament takes time to grow together.
Undergoing physical therapy in Carlsbad this week, Richardson said that she did what she could to educate herself about BEAR before approaching Wang to schedule surgery. That process, she said, included getting in touch with the first person to undergo a BEAR repair six years ago. Though she had already read the studies, she said getting a human reaction increased her confidence.
“He actually got back to me and said, ‘You know, it’s great, I still ski. I’ve had no issues,’” she said.