Comparison of graft healing in anterior cruciate ligament reconstruction with and without a preserved remnant in rabbits.

Background: The remnant of the native anterior cruciate ligament (ACL) might contribute to the biological integration of the graft in ACL reconstruction. The aim of this study was to explore whether the preserved remnant enhanced graft healing in ACL reconstruction. Methods: Forty New Zealand rabbits underwent bilateral anterior cruciate ligament reconstructions. One knee was treated with a 2-mm remnant preserved on the tibial side (remnant-preservation, RP group) while the contralateral knee underwent a complete removal of the remnants by cauterization (remnant-resection, RR group) in each animal. Gross observations combined with microangiography, histological evaluation, and uniaxial load testing were performed after 4,8, and 12 weeks. Results: The vascular density on the graft surface was statistically higher in the RP group as compared to that of the RR group at 4 (P = 0.002) and 8 weeks (P = 0.020). Additionally, the accelerated intra-articular and intra-tunnel graft integration were histologically observed in the RP group. Histological scores in the RP group were statistically higher than the RR group at 4 weeks (P = 0.028 for the intra-articular healing and P = 0.046 for the intra-tunnel healing) and 8 weeks (P = 0.031 for the intra-articular healing and P = 0.014 for the intra-tunnel healing). The ultimate failure load (P = 0.017), yield load (P = 0.025), and stiffness (P = 0.004) were statistically higher in the RP group as compared to those of the RR group, with corresponding significant differences in the failure mode (P = 0.020) between the two groups at 8 weeks. Conclusions: The preserved remnant enhanced ACL graft healing with improved biomechanical properties in the rabbit model. [ABSTRACT FROM AUTHOR]