Fourteen immature female 30kg Yorkshire pigs underwent unilateral ACL reconstruction using a bone-patellar tendon-bone allograft. ACL reconstruction with standard allograft (ACLR; control) was performed in 7 animals while the procedure was performed using the same allograft enhanced with CPC in 7 animals (E-ACLR; experimental). One animal in the control group was euthanized at the time of surgery due to a condylar fracture and was not included in the study. The study was 80% powered to detect an effect size of 2.
Following the induction of anesthesia and clinical examination of both knees, the knee was shaved, prepared with a surgical iodine solution and alcohol, and draped. An 8 cm incision was made at the medial border of the patellar tendon. The patella was retracted laterally without dislocating it from the trochlear groove. The fat pad was partially resected to expose the ACL, which was completely transected at the junction of the proximal and middle thirds of the ligament. ACL transection was verified by a positive Lachman exam.
The fresh frozen allografts were harvested from fourteen age, weight and gender matched donor knees. The entire patellar tendon, which was approximately 10 mm in width, was used. The bone blocks were trimmed to 7 mm diameter to allow for smooth graft passage through 8 mm osseous tunnels in the femur and tibia. The osseous tunnels were drilled to the insertion sites of the native ACL using a commercial drill guide system (Acufex Elbow Aimer, Smith & Nephew, Inc, Andover MA). Once the tunnels were completed, the graft was introduced intra-articularly through the arthrotomy. One bone block was passed into the femoral tunnel and rigidly fixed using a 6 mm bioabsorbable interference screw (CALAXO, Smith-Nephew, Andover, MA). In the standard ACLR group, the graft was then passed retrograde into the tibial tunnel, preconditioned using 20 cycles of firm manual tension, held in maximum manual tension, and secured in the tibia using another 6 mm interference screw. The tibial screw was inserted into the tibial tunnel at the distal end of the tunnel, and the screw was countersunk 3 mm below the cortical surface of the tibia (Fig. 1 ). In the E-ACLR group, a tubular collagen sponge (details below) was threaded onto the graft after femoral fixation. The graft was then pulled retrograde into the tibial tunnel, preconditioned, tensioned, and secured with another interference screw as described for the ACLR group. The concentrated platelets were added to the sponge to create the CPC.
The retinacula and subcutaneous tissues were closed with interrupted 2-0 Vicryl, and a 3-0 Vicryl subcuticular stitch was used to close the skin incision. The animals were allowed unrestricted weight bearing. Postoperative pain was controlled with narcotics. All animals were monitored closely after surgery for any signs of discomfort, lameness or weight loss. The pigs were euthanized after 15 weeks of healing. The knees were immediately harvested and frozen until mechanical testing.
Following the induction of anesthesia and clinical examination of both knees, the knee was shaved, prepared with a surgical iodine solution and alcohol, and draped. An 8 cm incision was made at the medial border of the patellar tendon. The patella was retracted laterally without dislocating it from the trochlear groove. The fat pad was partially resected to expose the ACL, which was completely transected at the junction of the proximal and middle thirds of the ligament. ACL transection was verified by a positive Lachman exam.
The fresh frozen allografts were harvested from fourteen age, weight and gender matched donor knees. The entire patellar tendon, which was approximately 10 mm in width, was used. The bone blocks were trimmed to 7 mm diameter to allow for smooth graft passage through 8 mm osseous tunnels in the femur and tibia. The osseous tunnels were drilled to the insertion sites of the native ACL using a commercial drill guide system (Acufex Elbow Aimer, Smith & Nephew, Inc, Andover MA). Once the tunnels were completed, the graft was introduced intra-articularly through the arthrotomy. One bone block was passed into the femoral tunnel and rigidly fixed using a 6 mm bioabsorbable interference screw (CALAXO, Smith-Nephew, Andover, MA). In the standard ACLR group, the graft was then passed retrograde into the tibial tunnel, preconditioned using 20 cycles of firm manual tension, held in maximum manual tension, and secured in the tibia using another 6 mm interference screw. The tibial screw was inserted into the tibial tunnel at the distal end of the tunnel, and the screw was countersunk 3 mm below the cortical surface of the tibia (
The retinacula and subcutaneous tissues were closed with interrupted 2-0 Vicryl, and a 3-0 Vicryl subcuticular stitch was used to close the skin incision. The animals were allowed unrestricted weight bearing. Postoperative pain was controlled with narcotics. All animals were monitored closely after surgery for any signs of discomfort, lameness or weight loss. The pigs were euthanized after 15 weeks of healing. The knees were immediately harvested and frozen until mechanical testing.