The Bridge-Enhanced ACL Restoration Procedure Offers Advantages Over Traditional Reconstruction Surgery

Bridge-Enhanced ACL Restoration (BEAR) is a surgical treatment option for patients who have sustained an ACL tear in their knee. Each year, nearly 250,000 ACL ruptures occur in the United States alone. The majority of these injuries are treated with surgery, most commonly, an ACL reconstruction by utilizing a graft. Graft options include allograft and autograft sources. Each option includes its own risk/reward profile. Autograft options typically include patellar tendon, quadriceps tendon and patellar tendon donor sites. These have all demonstrated positive clinical outcomes; they all also involve some form of donor site morbidity. Allograft ACL reconstructions do not include donor site morbidity, but re-injury rates have been shown to be nearly double those after autograft reconstructions. Healing rates and outcomes have been rather inconsistent. This is likely due to the intra-articular environment of the knee, which has been shown to inhibit fibrin clot formation, resulting in inconsistent and incomplete ACL healing. 

The BEAR procedure utilizes a proprietary resorbable implant derived from bovine sources, primarily extracellular matrix and collagen (Figure 1). The implant is surgically placed into the patient’s knee, along with suturing of the injured ACL tissue back to its original anatomic location. The BEAR implant acts as a bridge, allowing a clot to form between the torn ends of the ACL, thus allowing ligament healing and restoration of knee stability and proprioception (Figure 2). All of this is accomplished without the use of a graft to replace the injured ligament while demonstrating re-injury rates and patient outcomes that are comparable or non-inferior to ACL reconstruction.

Benefits of the BEAR Procedure

A number of potential benefits of this procedure are offered when compared to traditional ACL reconstruction. Given the BEAR procedure does not require a graft to replace the patient’s native ACL, there is no graft site morbidity associated with the procedure. This has been shown to result in significantly improved patient-reported postoperative pain scores in BEAR patients compared to ACL reconstruction patients. Early studies have also demonstrated superior hamstring-to-quadriceps strength ratios in BEAR patients compared to ACL reconstruction. This has the added benefit of decreased rates of contralateral knee ACL tears, which can be found in ACL reconstruction patients. One potential long-term benefit of the BEAR procedure may be a lower rate of long-term osteoarthritis progression. Most studies suggest at least 50% of patients with a history of ACL injury go on to develop radiographic evidence of arthritis. In pre-clinical porcine testing, the BEAR procedure demonstrated a significant reduction in knee osteoarthritis at 12 months post-procedure compared to both ACL transection and ACL reconstruction. If confirmed in long-term human studies, this may indeed be the greatest advantage of the BEAR procedure.   

Candidate Considerations

This procedure is indicated for the treatment of complete ACL tears in most patients. Current FDA approval includes patients 14 years and older with closed growth plates. However, the BEAR procedure can and has been used to safely treat ACL injuries in younger patients. In these cases, a growth plate sparing technique should be utilized. The timing of the patient’s injury and treatment is also important, as it is recommended to perform the BEAR procedure within 50 days from the initial ACL injury. Additional consideration should also be given to the type of ACL tear, as well as the patient’s activities and personal goals. As with any injury and proposed surgery, a robust discussion of the options and shared decision-making allows for the highest likelihood of success and patient/family satisfaction.

Surgery and Recovery 

The BEAR procedure is arthroscopically assisted and typically occurs in an outpatient (day surgery) setting. Postoperatively, patients are protected in a knee brace and crutches and referred to physical therapy to work on their range of motion and strengthening. Running and sport-specific training activities are typically initiated at the four- and six-month postoperative marks, respectively. Return to sport clearance/progression occurs no sooner than nine months after surgery, with most patients returning to their usual sports and activities between nine and 12 months after surgery. 

In summary, while it may not be the best fit for every patient, the BEAR procedure offers a novel treatment option for patients with an ACL tear. Ligament preservation offers significant potential advantages over ACL reconstruction. However, much remains to be learned regarding long-term benefits and outcomes.