The BEAR procedure was performed arthroscopically, with 4 mm tunnels drilled in the femur and tibia. First, the tibial stump was secured with a #2 absorbable suture (Vicryl; Ethicon) using a whip stitch. A cortical button (Endobutton; Smith & Nephew) with #2 nonabsorbable sutures (Ethibond; Ethicon) and the previous #2 absorbable sutures were passed through the femoral tunnel and secured to the proximal femoral cortex. The BEAR implant, composed of bovine-derived extracellular matrix proteins, was delivered via mini-arthrotomy, and secured by the #2 nonabsorbable sutures. The implant was then saturated with 5-10mL of autologous blood, and the ends of the torn ACL were passed through the implant.[30 (link), 32 (link)]