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FDA Approves New Implant for ACL Tears

Woman in bed with a knee brace after a knee injury.

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Key Takeaways

  • A new absorbable device known as the Bridge-Enhanced ACL Repair (BEAR) was approved by the Food and Drug Administration (FDA) to repair some anterior cruciate ligament (ACL) injuries.
  • Compared to traditional ACL reconstruction, the implant is a less invasive procedure that restores the knee’s natural anatomy and function.
  • Researchers are hopeful this implant will become the new standard of care for ACL injuries.

The U.S. Food and Drug Administration (FDA) approved a new implant that can repair some anterior cruciate ligament (ACL) injuries.

The FDA granted marketing authorization for an implant to repair the injury. The Bridge-Enhanced ACL Repair (BEAR) Implant is an alternative to ACL reconstruction, which typically requires harvesting tendons—and sometimes bone—from another part of the patient’s body or a deceased donor. It can also be done via sutures, a medical device used to hold body tissues together.

Marketing authorization allows manufacturers to bring a medicinal product to the market.

The new implant instead is made of proteins that are an integral part of the healing process, Braden Fleming, PhD, a professor of orthopedics at Brown University involved in the research, tells Verywell.

Martha Murray, MD, an orthopedic surgeon at Boston Children’s Hospital and professor at Harvard Medical School who spearheaded the research, notes that the implant is made of the same proteins found in the normal ACL. “So as the ACL cells move into the implant, they absorb the protein of the implant and replace it with new protein organized like the native ACL,” she tells Verywell.

Compared to traditional ACL reconstruction, the implant is a less invasive procedure that restores the knee’s natural anatomy and function. Patients report more satisfaction in terms of pain, symptoms, and readiness. It doesn’t require a second wound site to remove healthy tendon and does not involve donors.

ACL injuries affect between 100,000 to 200,000 people in the U.S. each year. The injury does not heal on its own, so ACL reconstruction is the only way to repair it. Many patients never regain their full level of physical activity, even after the procedure.

“There are a number of advantages to repairing a ligament instead of replacing it," Murray, who founded Miach Orthopaedics, which manufactures the implant, said in a statement. "That is why, more than 30 years ago, we set out to find a way to help the ligament heal itself."

What This Means For You

If you've torn your ACL and are interested in the new implant, you should talk to your doctors to see if you are a strong candidate for the new procedure or would be better off with an ACL reconstruction.

About the ACL Implant

The ACL implant isn’t a traditional device like those used in most joint repairs. It’s an absorbable implant that’s derived from bovine collagen—a naturally occurring protein present in the connective tissue. It bridges the gap between the torn ends of a patient’s ACL, and the body then absorbs the implant within about eight weeks of surgery. The body’s own tissue eventually replaces the implant.

During surgery, the patient’s own blood is injected into the implant to form a device-protected clot that enables the body to heal. 

In a randomized controlled trial of 100 people who experienced complete ACL rupture, 65 received the implant and 35 members in a control group had reconstruction via autograft, using tendon from their own bodies. Every patient underwent physical therapy after surgery, and the team followed them for two years.

At that time, those with the implant reported on their outcomes using the International Knee Documentation Committee Subjective Score, a knee-specific patient-reported outcome measure. They had an average score of 88.9, while those who underwent traditional ACL repair had an average of 84.8.

The patients were also measured using an arthrometer, which measures the range of movement in a joint. Measurements below 3 millimeters (mm) are considered normal. Patients with the implant had an average that was greater by 1.61 mm in the treated knee compared to their untreated knee. On the other hand, those in the control group had a laxity in the treated knee of 1.77 mm.

The implant is aimed at patients at least 14 years of age who have experienced a complete ACL rupture confirmed with magnetic resonance imaging (MRI) scan. The patient needs to have some tissue intact after the tear for the implant to work. And as it stands, implant recipients shouldn’t return to a sport for nine months after their surgery, which is similar to traditional ACL reconstruction, Fleming says.

A New Solution

Fleming says the FDA approval was exciting news that “provides a treatment alternative to ACL reconstruction that does not require removing the injured ligament and replacing it with a graft of tendon.”

Using the BEAR implant, no other structures in the body need to be compromised in order to harvest a graft to replace the injured ligament. “If the repair does fail, it is much easier to fix than when a graft fails,” he says. 

Adam S. Lepley, PhD, co-director of the Michigan Performance Research Laboratory at the University of Michigan, who specializes in rehabilitation, noted that traditional ACL reconstruction focuses on rebuilding the ligament while the implant centers on repairing it.

“In theory, this is ideal, as it would be healing of native tissue to the knee and not require injuring a different portion of the body to just fix another,” Lepley tells Verywell. “Historically, the repair method of just suturing the two ends together has not been very effective."

Fleming says research is ongoing at Boston Children's Hospital, University Orthopedics, and Rhode Island Hospital to determine if there are specific patients that may do particularly well or may not do as well following the BEAR procedure. 

A doctor has to weigh which patients would be an ideal candidate to receive the implant over traditional ACL reconstruction. “It’s not something that every patient will be eligible for,” Alan Getgood, MD, an orthopedic surgeon specializing in knee reconstruction at the Fowler Kennedy Sport Medicine Clinic in Canada, tells Verywell. For those looking for a “tried and tested” method, and who may need to get back to activity quickly, they may want to stick with a traditional ACL repair, Getgood says.

"We are working hard to determine if there are specific factors that would identify patients who would be ideal candidates,” Fleming says. “Despite this, the young and active population that BEAR was tested had excellent outcomes that were at least as similar as those receiving ACL reconstruction.”

Murray points out that patients who incurred an ACL months ago or who have little ACL tissue left would be more likely to benefit from an ACL reconstruction, rather than this implant. “We think you need to have sufficient ACL tissue left to repair for the surgery with the implant to work,” Murray says.

Becoming the Standard for ACL Care

In a statement, Martha Shadan, president and CEO of Miach Orthopaedics, said the implant represented the first substantial advancement in the treatment of ACL tears in decades. She said it had the “potential to change the standard of care.”

The gold standard of ACL rupture is using a graft of tendon to replace the ACL, Fleming explains. The data supporting the implant is very encouraging. Data on the first patients who got the implant reporting on their six-year post-surgical outcomes is starting to come in, he says.

“So far, so good,” Fleming reports. “Given that most reinjuries following BEAR and ACL reconstruction occur within the first year, the long-term results are likely to remain excellent.”

Fleming says it will be interesting to see if the rate of arthritis following implant insertion will be less than in patients receiving ACL reconstruction as the team’s preclinical studies suggest.

“I am confident that it is a viable alternative to ACL reconstruction as it does not require graft harvest, it does not compromise muscle function, and there is evidence in preclinical models that the procedure reduces arthritis, a long-term problem associated with ACL reconstruction surgery,” he says. “If the latter holds true in clinical patients, then the impact of the BEAR procedure will be even greater.”

“Whether it replaces ACL reconstruction as the gold standard remains to be seen but I am optimistic it will,” Fleming adds.

Murray also believes the implant will be a new gold standard for ACL repair in the future.

“These initial studies demonstrated that even the first surgeries performed for this technique had similar outcomes to the current gold standard of ACL reconstruction with autograft tendon, and patients did not have to have a graft harvested from their leg,” she says. “BEAR represents a move toward a less invasive and equally effective surgical treatment for patients with ACL injuries.” 

The caveat about using the implant is that the technique is most effective if the ligament ruptures mid-substance, or about the middle of the ligament, to provide two ends that are able to be sutured together. 

“The preliminary work is very promising, but with any new research, we need more data to confirm the early findings,” Lepley says. “If those that undergo the BEAR procedure return to sports faster and have lower rates of re-injury and osteoarthritis, it is definitely possible that it could become the new gold standard.” 

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  1. U.S. Food and Drug Administration. FDA authorizes marketing of new implant to repair a torn ACL. Updated December 16, 2020.

  2. Harvard Health Publishing. ACL (anterior cruciate ligament) injuries. Updated April 2020.

  3. Businesswire. Miach Orthopaedics’ BEAR® implant granted FDA de novo approval for treatment of ACL tears. Updated December 17, 2020.

  4. Murray, M, et al. Bridge-enhanced anterior cruciate ligament repair is not inferior to autograft anterior cruciate ligament reconstruction at 2 years: results of a prospective randomized clinical trial. The American Journal of Sports Medicine. April 16, 2020. doi:10.1177/0363546520913532