Preservation of Remnant Attachment Improves Graft Healing in a Rabbit Model of Anterior Cruciate Ligament Reconstruction

Abstract

To determine the effect of remnant preservation on the healing of anterior cruciate ligament (ACL) tendon graft after reconstruction in an animal model. Fifty-two New Zealand rabbits were divided into 6 groups. Revascularization and graft healing were studied in groups 1 through 4 (n= 8 each). The biomechanical properties of the graft complex were evaluated in group 5 (n= 12). The blood flow and biomechanical characteristics of the intact ACL were evaluated in group 6 (n= 8). Both knees of each rabbit were subjected to ACL reconstruction with 2-mm grafts of Achilles tendon splits. The right knees were reconstructed with remnant preservation, whereas the remnants in the left knees were debrided. The revascularization and remodeling of grafts were evaluated at 6, 12, 18, and 24 weeks after reconstruction. Tendon-to-bone integration was investigated histomorphologically. The tensile load strengths of graft complexes were also tested. The blood flow in the graft was significantly higher in the remnant-preserved group than in the remnant-debrided group (P < .01). Specifically, the blood flow of the graft with remnant preservation was markedly enhanced at 6 weeks and 12 weeks after reconstruction (P < .05). The number of CD34-positive vessels in the graft was higher in the remnant-preservation group (P < .05). The ligamentization and remodeling of the graft were improved and the collagen type III content in the graft was higher in the remnant-preserved group (P < .05). Tendon-to-bone integration was improved by remnant preservation. At 24 weeks after reconstruction, the failure load of the graft complex was significantly higher in the remnant-preserved group (23.46 ± 7.40 N) than in the remnant-debrided group (18.63 ± 4.26 N) (P< .05). The preservation of the remnant attachment in ACL reconstruction improved the revascularization and remodeling of the graft and enhanced the biomechanical properties of the integrated graft. Preservation of the remnant attachment may benefit healing of the tendon graft in ACL reconstruction.