BEAR Necessities Blog

5 Facts About the BEAR® Implant You May Not Know

The BEAR Facts

Since its approval by the U.S. Food and Drug Administration more than three years ago, the BEAR® Implant has been adopted by hundreds of surgeons across the U.S. as a new approach to treating a torn anterior cruciate ligament (ACL). The BEAR Implant enables a patient to heal their torn ACL instead of replacing it with a graft in an ACL reconstruction (ACLR).

Since it is a relatively new treatment for ACL tears, there are some misconceptions about the BEAR Implant, ranging from tear types that are eligible to how soon the procedure should be performed after injury. Here are five facts about the BEAR Implant you may not know:

1. The BEAR Implant Procedure is Flexible to Surgeon Preference

Though the BEAR Implant was evaluated in clinical trials using the surgical technique developed at Boston Children’s Hospital, the approval by the FDA does not require that specific procedure be used in clinical practice. What that means for orthopedic surgeons is that there is flexibility in surgical approach as long as the three core constructs that were part of the original surgical technique are met:

  • The ACL stump is under tension and reapproximated directionally to the other stump. Appropriate tension helps ensure the cells regrow toward the other stump.
  • The BEAR Implant secured with a suture and in contact with the two torn ends of ACL stump. This helps the implant remain in the appropriate location to provide a healing environment for the ACL.
  • The knee is stabilized with an internal support suture. Bone-to-bone fixation provides support to the knee, helping protect the repair and ensure alignment in the initial healing stages.

The remaining aspects of the surgery are left to surgeon discretion, such as surgical instrumentation and whether to use buttons, anchors or knots. Experienced BEAR Implant surgeons find that the BEAR Implant is adopted seamlessly into their existing ACL surgical practice and has very little impact on procedure length.

2. Most ACL Tears Are Appropriate for the BEAR Implant

While many people assume the BEAR Implant is best for proximal tears, it is indicated for a broad range of ACL tear types, from proximal avulsion to distal tears. In fact, among the first 1,600 patients treated since FDA approval, half of patients had mid-substance tears and one-third had proximal tears.

But what about tears with short stumps? You may have heard that if you can get three sutures in the stump, you can do the BEAR procedure. While three sutures were required in clinical studies, in clinical practice the main requirement for using a BEAR Implant is the ability to place enough tension on tibial stump to directionally pull it toward the other stump. Many surgeons have found that they’re able to elongate a short stump by pulling it with a grasper or suture, enabling a BEAR procedure to be possible for the majority of patients.

3. ACL Stumps “Hide” on MRI

The value of the MRI is undeniable with regard to diagnosing an ACL tear. Its utility may be limited, however, in helping surgeons determine which patients are appropriate BEAR Implant candidates. In fact, preliminary results of a study by Drs. Shawn Anthony and Sean McMillan shared in an industry forum at a 2023 medical meeting showed that MRI accurately predicted BEAR eligibility only about half the time.

Multiple factors influence whether the MRI will be a good predictor for whether a patient is eligible for the BEAR Implant, including how old the MRI is, the quality of the MRI and the position of the stump – it could look small when in reality it is lying down or has accordioned. As a result, many BEAR surgeons consent patients for both reconstruction and restoration with the BEAR Implant. The surgeons then can decide the best course of action once they can see the ACL stump on the scope during the procedure.

4. BEAR Surgery Can Be Performed Days, Weeks or Months After ACL Injury

Many people think that the BEAR Implant should be implanted within 50 days of injury. While that was required in the clinical trials in order to remove tissue quality as a variable to outcomes, eligibility for BEAR Implant surgery is based on one thing: the quality of the remaining tissue as assessed by the orthopedic surgeon using a scope. While earlier is better because the quality of the remaining tissue degrades over time, everyone’s tissue degrades at different speeds. Therefore, assessing the tissue quality is more important than adhering to a specific window of time.

5. Retear Rates Are in Line with ACLR

In the literature, the reported retear rate for adolescents undergoing ACLR ranges from 10-25%. In the BEAR I, II and III clinical studies, two-year data from surgeries performed at Boston Children’s Hospital showed a retear rate of 15% (18/123) for patients who received the BEAR Implant. Additionally, in the BEAR I study, soon to be published six-year data show a retear rate of 11% (1/9) which was equivalent to the ACLR group at 14% (1/7). That study also found no differences between the hamstring tendon ACLR group and BEAR Implant groups in any of the outcome measures, except for hamstring strength, which was approximately equal to that of the contralateral knee in the BEAR group and 44% less than the contralateral knee in the ACLR group.

Miach Orthopaedics is collecting additional, multi-center data on retear rates through the BEAR III and Bridge Registry studies. These studies will begin publishing interim results in mid-to-late 2024.

The BEAR Implant from Miach Orthopaedics was approved by the U.S. Food and Drug Administration in December 2020. It is indicated for skeletally mature patients at least 14 years of age with a complete rupture of the ACL confirmed by MRI. Patients must have an ACL stump attached to the tibia to facilitate the restoration.

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 ACL reconstruction. These include the risk of re-tear, infection, knee pain, meniscus injury and limited range of motion.

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