title: The Bridge-Enhanced Anterior Cruciate Ligament Repair (BEAR) Procedure: An Early Feasibility Cohort Study.
abstract: 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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children's Hospital Boston, Massachusetts, USA.
authors.forename: Martha M
authors.initials: MM
authors.lastname: Murray
authors.affiliation: Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children's Hospital Boston, Massachusetts, USA.
authors.forename: Brett M
authors.initials: BM
authors.lastname: Flutie
authors.affiliation: Clinical Research Center, Boston Children's Hospital Boston, Massachusetts, USA.
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Kalish
authors.affiliation: Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Ecklund
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School of Brown University/Rhode Island Hospital, Providence, Rhode Island, USA.
authors.forename: Braden C
authors.initials: BC
authors.lastname: Fleming
authors.affiliation: Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children's Hospital Boston, Massachusetts, USA.
authors.forename: Benedikt L
authors.initials: BL
authors.lastname: Proffen
authors.affiliation: Division of Sports Medicine, Department of Orthopaedic Surgery, Boston Children's Hospital Boston, Massachusetts, USA.
authors.forename: Lyle J
authors.initials: LJ
authors.lastname: Micheli
keywords: ACL reconstruction; ACL repair; BEAR; anterior cruciate ligament; bridge-enhanced ACL repair; human