The Bridge-Enhanced Anterior Cruciate Ligament Repair (BEAR) Procedure: An Early Feasibility Cohort Study
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The Bridge-Enhanced Anterior Cruciate Ligament Repair (BEAR) Procedure
Martha M. Murray 0
Brett M. Flutie 0
Leslie A. Kalish 0
ScD 0
Kirsten Ecklund 0
Braden C. Fleming 0
Benedikt L. Proffen 0
Lyle J. Micheli 0
0 Investigation performed at Boston Children's Hospital , Boston, Massachusetts , USA
Background: This study assessed the safety of the newly developed bridge-enhanced anterior cruciate ligament (ACL) repair (BEAR), which involves suture repair of the ligament combined with a bioactive scaffold to bridge the gap between the torn ligament ends. As the intra-articular environment is complex in its response to implanted materials, this study was designed to determine whether there would be a significant rate of adverse reaction to the implanted scaffold. Hypothesis: The primary hypothesis was that the implanted scaffold would not result in a deep joint infection (arthrocentesis with positive culture) or significant inflammation (clinical symptoms justifying arthrocentesis but negative culture). The secondary hypotheses were that patients treated with BEAR would have early postoperative outcomes that were similar to patients treated with ACL reconstruction with an autologous hamstring graft. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 20 patients were enrolled in this nonrandomized, first-in-human study. Ten patients received BEAR treatment and 10 received a hamstring autograft ACL reconstruction. The BEAR procedure was performed by augmenting a suture repair with a proprietary scaffold, the BEAR scaffold, placed in between the torn ends of the ACL at the time of suture repair. The BEAR scaffold is to our knowledge the only device that fills the gap between the torn ligament ends to have current Investigational Device Exemption approval from the Food and Drug Administration. Ten milliliters of autologous whole blood were added to the scaffold prior to wound closure. Outcomes were assessed at 3 months postoperatively. The outcomes measures included postoperative pain, muscle atrophy, loss of joint range of motion, and implant failure (designated by an International Knee Documentation Committee grade C or D Lachman test and/or an absence of continuous ACL tissue on magnetic resonance images). Results: There were no joint infections or signs of significant inflammation in either group. There were no differences between groups in effusion or pain, and no failures by Lachman examination criteria (BEAR, 8 grade A and 2 grade B; ACL reconstruction, 10 grade A). Magnetic resonance images from all of the BEAR and ACL-reconstructed patients demonstrated a continuous ACL or intact graft. In addition, hamstring strength at 3 months was significantly better in the BEAR group than in the hamstring autograft group (mean ± SD: 77.9% ± 14.6% vs 55.9% ± 7.8% of the contralateral side; P < .001). Conclusion: The results of this study suggest that the BEAR procedure may have a rate of adverse reactions low enough to warrant a study of efficacy in a larger group of patients.
anterior cruciate ligament; human; ACL reconstruction; ACL repair; bridge-enhanced ACL repair; BEAR
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in ligaments (such as the medial collateral ligament
[MCL]) that heal without surgical intervention. Preclinical
work in large animal models has suggested that placement
of a sponge capable of absorbing blood and stabilizing it
in the ACL wound site can stimulate healing of the
ligament.8,15,21 When this technique is combined with
mechanical stabilization of the knee with a suture repair, the
outcomes are similar between the bridge-enhanced ACL
repair, or BEAR procedure, and ACL reconstruction in
preclinical models.21,33
Prior studies using native polymers and tissues
to enhance soft tissue repair within joints have been
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conducted, most commonly in the shoulder for rotator cuff
surgery.13,17,29 Perhaps the most well-known of these
implants is the RESTORE patch (DEPUY), a crosslinked,
mechanically strong, construct made of porcine small
intestine submucosa. The RESTORE patch was used to
augment suture repair of the rotator cuff tendon in 2
studies: a randomized control trial of 30 patients13 and a
second study of 25 patients who had the RESTORE patch
implanted.17 In the first study, 3 (20%) of 15 RESTORE
patients developed erythema, pain, and swelling at the
shoulder within 6 weeks of implantation.13 In the second
study, 4 (16% (...truncated)