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Randomized Controlled Trial
. 2020 May;48(6):1305-1315.
doi: 10.1177/0363546520913532. Epub 2020 Apr 16.

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

Martha M Murray  1 , Braden C Fleming  1 , Gary J Badger  1 ; BEAR Trial Team  1 ; Christina Freiberger  1 , Rachael Henderson  1 , Samuel Barnett  1 , Ata Kiapour  1 , Kirsten Ecklund  1 , Benedikt Proffen  1 , Nicholas Sant  1 , Dennis E Kramer  1 , Lyle J Micheli  1 , Yi-Meng Yen  1
Affiliations
Randomized Controlled Trial

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

Martha M Murray et al. Am J Sports Med. 2020 May.

Abstract

Background: Preclinical studies suggest that for complete midsubstance anterior cruciate ligament (ACL) injuries, a suture repair of the ACL augmented with a protein implant placed in the gap between the torn ends (bridge-enhanced ACL repair [BEAR]) may be a viable alternative to ACL reconstruction (ACLR).

Hypothesis: We hypothesized that patients treated with BEAR would have a noninferior patient-reported outcomes (International Knee Documentation Committee [IKDC] Subjective Score; prespecified noninferiority margin, -11.5 points) and instrumented anteroposterior (AP) knee laxity (prespecified noninferiority margin, +2-mm side-to-side difference) and superior muscle strength at 2 years after surgery when compared with patients who underwent ACLR with autograft.

Study design: Randomized controlled trial; Level of evidence, 1.

Methods: One hundred patients (median age, 17 years; median preoperative Marx activity score, 16) with complete midsubstance ACL injuries were enrolled and underwent surgery within 45 days of injury. Patients were randomly assigned to receive either BEAR (n = 65) or autograft ACLR (n = 35 [33 with quadrupled semitendinosus-gracilis and 2 with bone-patellar tendon-bone]). Outcomes-including the IKDC Subjective Score, the side-to-side difference in instrumented AP knee laxity, and muscle strength-were assessed at 2 years by an independent examiner blinded to the procedure. Patients were unblinded after their 2-year visit.

Results: In total, 96% of the patients returned for 2-year follow-up. Noninferiority criteria were met for both the IKDC Subjective Score (BEAR, 88.9 points; ACLR, 84.8 points; mean difference, 4.1 points [95% CI, -1.5 to 9.7]) and the side-to-side difference in AP knee laxity (BEAR, 1.61 mm; ACLR, 1.77 mm; mean difference, -0.15 mm [95% CI, -1.48 to 1.17]). The BEAR group had a significantly higher mean hamstring muscle strength index than the ACLR group at 2 years (98.2% vs 63.2%; P < .001). In addition, 14% of the BEAR group and 6% of the ACLR group had a reinjury that required a second ipsilateral ACL surgical procedure (P = .32). Furthermore, the 8 patients who converted from BEAR to ACLR in the study period and returned for the 2-year postoperative visit had similar primary outcomes to patients who had a single ipsilateral ACL procedure.

Conclusion: BEAR resulted in noninferior patient-reported outcomes and AP knee laxity and superior hamstring muscle strength when compared with autograft ACLR at 2-year follow-up in a young and active cohort. These promising results suggest that longer-term studies of this technique are justified.

Registration: NCT02664545 (ClinicalTrials.gov identifier).

Keywords: ACL reconstruction; ACL repair; BEAR; anterior cruciate ligament; bridge-enhanced ACL repair; human; scaffold-enhanced ACL repair.

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Conflict of interest statement

One or more of the authors has declared the following potential conflict of interest or source of funding: This study received funding support from the Translational Research Program at Boston Children’s Hospital, the Children’s Hospital Orthopaedic Surgery Foundation, the Children’s Hospital Sports Medicine Foundation, the Football Players Health Study at Harvard University, and the National Institutes of Health and the National Institute of Arthritis and Musculoskeletal and Skin Diseases through grants R01-AR065462 and R01-AR056834. M.M.M. is a founder, paid consultant, and equity holder in Miach Orthopaedics, Inc, which was formed to work on upscaling production of the BEAR scaffold. M.M.M. maintained a conflict-of-interest management plan that was approved by Boston Children’s Hospital and Harvard Medical School during the conduct of the trial, with oversight by both conflict-of-interest committees and the institutional review board of Boston Children’s Hospital, as well as the US Food and Drug Administration. B.C.F. is an assistant editor for The American Journal of Sports Medicine, the spouse of M.M.M. with the inherently same conflicts. D.E.K., L.J.M., and Y.-M.Y. all have disclosures as listed in the American Academy of Orthopaedic Surgeons database, none of which are related to this current project or technology. These include educational payments from Kairos Surgical (D.E.K., Y.-M.Y.) and food, beverage, and travell reimbursements from 5 companies (each <$500). L.J.M. also has received multiple payments for food and beverage from various companies. For the BEAR Trial Team, B.P. has manufactured the scaffolds used in the trials at Boston Children’s Hospital and is a paid consultant and equity holder in Miach Orthopaedics at this time, as he assists with transfer of the manufacturing process to the contract manufacturing organization that Miach has engaged to do the manufacturing. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Figures

Figure 1.
Figure 1.
Schematic of the technique used to place the BEAR implant. Upper left panel: A suture (purple) is placed through the tibial stump via a whipstitch and secured with 2 free sutures (green) to an extracortical button. Upper right panel: After a cortical button carrying free sutures (green) is passed up through the femoral tunnel, the BEAR implant is loaded onto them and soaked with up to 10 mL of autologous blood. Lower left panel: The free suture ends (green) at the tibial end of the BEAR implant (which was positioned between the 2 ends of the torn ACL) are passed through the tibial tunnel to be tied over a second extracortical button. Lower right panel: The sutures and extracortical buttons are secured. ACL, anterior cruciate ligament; BEAR, bridge-enhanced ACL repair.
Figure 2.
Figure 2.
CONSORT (Consolidated Standards of Reporting Trials) diagram detailing patient flow through the study. ACLR, anterior cruciate ligament reconstruction; AP, anteroposterior; BEAR, bridge-enhanced anterior cruciate ligament repair; BPTB, bone–patellar tendon–bone; IKDC, International Knee Documentation Committee; PE, physical examination; ROM, range of motion.
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