Reconstructing ACL Treatment Paradigms

The anterior cruciate ligament (ACL) is one of the two ligaments that crosses the middle of the knee. It connects the thighbone to the shinbone and helps to stabilize the knee joint. Tearing it is one of the most common athletic injuries, often sidelining an athlete for the remainder of the season.

Most ACL injuries happen during sports and fitness activities that put stress on the knee. Suddenly slowing down and changing direction or pivoting with a foot firmly planted can cause the injury. So can landing from a jump incorrectly, stopping suddenly, or receiving a direct hit to the knee.

Reconstruction surgery to replace a torn ACL involves removing the torn ligament and replacing it with a graft tendon, which is either taken from another part of the patient’s knee or from a deceased donor.

The ACL unfortunately can’t heal on its own—the synovial fluid in the joint for proper knee function prevents the formation of blood clots that are critical for healing.

A few enterprising orthopedic device firms aim to improve or replace the paradigm of ACL reconstructive surgery. The first is Arthrex, with its ACL TightRope II fixation implant.

TightRope II, according to Arthrex, is the first adjustable-loop cortical suspensory fixation implant to use the company’s proprietary flat SutureTape design. The company claims it has better handling characteristics and is more resistant to graft abrasion or tissue pull-through than typical round sutures.

TightRope II is engineering for precise graft tensioning—its adjustable-loop mechanism facilitates incremental retensioning of the graft after the implants have been attached to the cortex. TightRope II also features a redesigned cortical button with a proprietary knotless fifth locking mechanism, which, according to Arthrex, increases strength and resistance to cyclic displacement.

In early January, the TightRope implant earned U.S. Food and Drug Administration (FDA) clearance for pediatric patients, becoming the first and only ACL fixation device cleared to do so.

“For more than a decade, Arthrex has worked closely with leading orthopedic surgeons from HSS to develop minimally invasive solutions for pediatric and young adolescent ACL surgery,” Arthrex president and founder Reinhold Schmieding told the press. “We are proud to partner with surgeons from the Hospital for Special Surgery to design treatment options specifically for ACL injuries in younger patients.”

To gain this indication, Arthrex developed an all-epiphyseal technique for skeletally immature patients that avoids pediatric growth plates to repair or reconstruct the ACL. Pediatric-specific instrumentation guides let surgeons drill sockets for the new, reconstructed ACL by avoiding the growth plate, lessening the risk of growth disturbance. In older adolescent patients with skeletal maturation, surgeons will drill across the growth plates to reconstruct the ACL using an all-soft-tissue autograft.

“These pediatric- and young-adolescent-specific guides help surgeons address the young athlete’s unique anatomy, greatly enhancing surgical options for reconstruction and epiphyseal fixation for ligamentous reconstruction or avulsion injury repair,” said Dr. Daniel W. Green, M.D., MS, FAAP, FACS, from the Hospital for Special Surgery (HSS).

The second orthopedic firm revolutionizing ACL repair and reconstruction is Miach Orthopaedics. The company’s BEAR (Bridge-Enhanced ACL Repair) implant, according to Miach, is the first medical advancement to enable the body to heal a torn ACL, working with the patient’s own blood to mend the torn ends back together.

The BEAR implant acts as a bridge to help the ACL’s torn ends heal together. It’s designed to hold and protect the blood in the gap between ACL ends to allow formation of a clot, which is necessary for healing. The patient’s blood is added to the implant, and inserted between the ACL’s torn ends. The BEAR implant is then replaced with the healed ACL. The implant can restore torn ACL quality and size similar to the non-injured ACL.

“ACL injuries are all too common among athletes of all ages and can be a career-ending injury in the NFL, which is why the NFL Players Association has been a sponsor of the BEAR clinical trials since the beginning,” Sean Sansiveri, VP, NFL Players Association, said when the BEAR implant earned FDA de novo approval in December 2020. “We’re gratified to have supported Miach Orthopaedics in the journey to bring a better option for treating ACL injuries to patients in the U.S.”

Miach released the implant in the U.S. in December 2021 and it was also awarded a Popular Science “Best of What’s New Award” for representing a significant step forward in health.

“We’ve been overwhelmed by the interest from patients who’ve torn their ACLs and are actively seeking an alternative to the current standard of care,” former Miach President/CEO Martha Shadan said. “We’re honored the BEAR Implant was selected by Popular Science as one of the best new health products of the year, and we are excited to make this innovative treatment available for patients.”

Just a few weeks ago, the company closed $40 million in financing to further expand the BEAR implant’s U.S. rollout as well as fund ongoing operations.