When you injure your ACL, the goal is to restore your knee to its natural state so that it functions and feels like it did before the injury.

The most common approach to ACL injuries is ACL reconstruction (ACLR), which involves removing the ACL tissue and replacing it with a graft from another part of your leg or from a deceased donor. But many patients do not regain the awareness, feel and function of their knee after an ACLR. Specifically, they do not fully recover proprioception: the ability to sense their knee joint’s movement, action and location. Loss of proprioceptive function affects the range of motion and stability of the joint, which can lead to further injuries, including to the articular cartilage, meniscus, and other important structures. 

The BEAR Implant is an ACL surgery that enables the body to heal its torn ACL, returning it to its original, natural state – including proprioception – with minimal disruption.

Lack of Proprioception is a Key Downside of ACL Reconstruction

In replacing the ACL tissue with a graft, ACLR removes the small nerves that normally run through the ligament. Called mechanoreceptors, these specialized sensory receptors detect mechanical stimuli like pressure, touch, stretch, or vibration and communicate this information to the central nervous system.

“All the nerve endings give the sense of proprioception, which gives your brain the sense of where your body has its limbs positioned in space,” says Dr. Timothy Crall, an orthopedic surgeon with Mammoth Orthopedic Institute in California.

Several research studies have highlighted proprioception deficits in patients following ACLR.

• A recent study of patients who received bone patella tendon bone (BTB) ACLR shows that the surgery does not preserve the knee’s mechanoreceptors. The researchers concluded that these findings support the consideration of remnant-preserving techniques or emerging methods such as the BEAR Implant, which may promote biological healing and restore proprioceptive capabilities, and that future studies should explore innovative strategies for enhancing reinnervation and sensory recovery in ligament reconstruction procedures to improve long-term functional outcomes.

• A study of patients who received either autograft or allograft found a reduced concentration of neurofilament protein (NFP), which is known to be present in mechanoreceptor tissue, compared with native ACL tissue. The researchers concluded these findings may explain the continued proprioceptive deficits seen clinically after ACLR.

• Another study suggests that ACL injury worsens proprioception in both the injured and non-injured knee, even after ACLR. Researchers found that deterioration of proprioception in the injured knee will not recover, and the non‐injured knee will become worse after one year from the injury.

BEAR Can Preserve Proprioception

Techniques that repair the ACL by preserving the remaining tissue and promoting natural healing, such as the BEAR Implant, could lead to better proprioception and joint function outcomes.

Although most tissue is repaired through the body’s natural healing process, the ACL’s biological response to injury limits its ability to self-heal. Specifically, there is no clot or tissue that can bridge the site of injury and serve as a scaffold for the formation of new tissue and blood vessels.

The BEAR Implant encourages healing and provides a stable clot and provisional scaffold to bridge the gap between the torn ends of the ACL. The BEAR Implant helps heal the ACL by supporting cell migration and proliferation, thereby facilitating the body’s own healing response. The implant is resorbed within eight weeks and replaced with native cells, collagen, and blood vessels.

“BEAR is different because with an ACL repair, you’re preserving the patient’s natural anatomy, you’re preserving those nerve endings, you’re preserving that proprioceptive feedback,” Dr. Crall says. “So once the ACL is able to heal with the BEAR Implant’s assistance, then all of those nerve endings are restored, and the proprioceptive feedback is restored to the patient’s brain. The knee will feel more normal, and they can go back to their sports.”

Patients and Surgeons Agree: The BEAR Implant Restores Feel and Function

Athletes, in particular, need to recover proprioception if they are to regain the level of skill and participation they had in their sport before their injury. This sensory input helps them to maintain balance and coordinate movements.

Athletes of all ages and skill levels who have received the BEAR Implant have shared why proprioception is important to them and how their knees feel:

• “I chose the BEAR Implant because it allows me to preserve the natural proprioception of my knee, and I wouldn’t have to use donor issue or take from my own hamstring, quad or patellar tendon.” –  Aaron Petruccelli, a police officer who does jiu-jitsu.
• “Since returning to hockey, my BEAR Implant knee has felt perfectly fine and normal.” – Henry LaVoie, a high school hockey and lacrosse player.
• “I rarely even think about my BEAR knee now.” – Amy Hafensteiner, who is back to yoga, soccer, basketball, water skiing and running, including the 2024 NYC Marathon.
• “Athletes typically say they feel different after an ACL surgery, but I feel like I am the same player today.” – Becky Contreras, a college soccer player.

Surgeons agree that the BEAR Implant helps their patients get back the feel and function of their knee joint.

• “The BEAR Implant is a great option for young athletes because it allows their ACL to heal naturally, preserves their nerve fibers and allows the knee to move in a more normal fashion.” – Dr. Sean Keyes, a pediatric orthopedic surgeon from AdventHealth in Florida who has performed more than 100 BEAR Implant procedures
• “My hope in offering the ACL repair with the BEAR Implant is that patients can feel their knee is more natural than if they had an ACLR, given it’s their own tissue with retained nerve endings.” – Dr. Jonathan Hagen, orthopedic surgeon at Tahoe Forest Health System and Tahoe Forest Orthopedics & Sports Medicine in California

The BEAR Implant from Miach Orthopaedics was approved by the U.S. Food and Drug Administration in December 2020. It is indicated for adults, adolescents and children with a complete or partial rupture of the ACL, as confirmed by MRI. Patients must have an ACL stump attached to the tibia to construct the repair. Children with open physes must have sufficient bone in the femoral and tibial epiphyses on either side of the intended tunnel locations to avoid disruption of the growth plates.

It is important to follow the BEAR Implant physical therapy program. Your surgeon can explain the program details.

Be sure to discuss your individual symptoms, diagnosis and treatment with your surgeon. The BEAR Implant has the same potential medical/surgical complications as other orthopedic surgical procedures, including ACLR. These include the risk of re-tear, infection, knee pain, meniscus injury and limited range of motion.

Visit www.miachortho.com for complete product information, including Instructions for Use.

ML-1255 Rev A 01/2025