| ObjectiveTo observe the effects of anterior cruciate ligament (ACL) reconstruction with preserving the remnant under sealing the bone tunnels on healing of ACL autograft, and discuss the reasons of the effects, provid the theoretical basis for the preserving-remnant technique.Methods1. Experimantal treatmentForty-eight closed colony New Zealand rabbits were divided into four groups at random, each group had 12 rabbits. The anterior cruciate ligament of the rabbit was cut off, the remnant of original ACL was preserved on one side and removed on the opposite side at random, then single bundle anterior cruciate ligament reconstruction under sealing the bone tunnels was conducted with autogeneous achilles tendon graft. After the operation, the animals in 4 groups were feeded in cage for 4, 8, 12, 12 weeks respectively.2. Observation indexes2.1 Function Assessmant Score:The Active motion, passive motion and joint stability of the knee were observated and recorded at 4, 8, 12 weeks postoperatively;2.2 Observation of Revasculization of the Graft:Animals in Group1 to 3 were executed and given vascular perfusion with formaldehyde-carbon-ink on scheduled time. The knee specimens were taken to observe the vessels in the graft;2.3 Histological Observation:The knee specimens were fixed with 10 % paraformaldehyde, decalcified with 10 % EDTA.The ACL specimens were taken and embeded, sliced, and then strained with HE and Masson special histochemistry to observe histopathological situation;2.4 Biomechanical Assessmant:Executed the rabbits of group 4 in 12 weeks after operation and harvested the sample of ACL grafts. The maximal failure load and the rupture site was observed were recorded with 858Mini BionixⅡsystem.3. Statistical Analysis:2×3 factorial analysis,One-Way Analysis of Variance,paired t test were carried out using SPSS12.0 software.Results1. Function Assessmant Score:In each time section, Function Assessmant Score of the knee in preserving-remnant group was higher than removing-remnant group, there was significant difference between two groups (P<0.05). There was significant difference between the 4 week time group and the 12 week time group(P<0.05);There was't significant difference among the other different time sections in each treatment group (P>0.05).2. Observation of Revasculization of the Graft:In each time section, the number of ACL grafts / vessel of preserving-remnant group was higher than removing-remnant group, there was significant difference between two groups(P<0.05). The number of 8 week time section was higher than 4 week time section and 12 week time section. There was significant difference among different time sections in each treatment group (P<0.05).3. Biomechanical Assessmant :At 12 weeks after operation, the maximum failure load of ACL grafts in preserving-remnant group was higher than that in removing-remnant group, there was significant difference between two groups (P<0.05).4.Interface Histopathological Observation of the graft : In each time section, the histological appearance of ACL grafts of preserving-remnant group was batter than removing-remnant group. All the rupture site in the preserving remnants group was at the intraarticular part of the graft except one at the tendon-bone interface, in contrast, in removing remnants group rupture site was at intraarticular part in 9 grafts,at tendon-bone interface in 2 grafts and pull out from the bone tunnel in one graft.Conclusion 1. Under sealing the bone tunnal with polyethylene membrane between the bone and the graft, the graft healing is depended on"creeping substitution"from intraarticular cells and tissue, which maybe play much more important role in graft incorporation.2. The ACL reconstruction by preserving-remnant can promote the restoration of blood supply of the ACL grafts.3. The ACL reconstruction by preserving-remnant is beneficial to the newborn cells/ growing in of the ACL grafts.4. The ACL reconstruction by preserving-remnant is beneficial to the improvement of biomechanical properties of the ACL grafts.5. The ACL reconstruction by preserving-remnant is beneficial to the histological maturity of the ACL grafts.6. The ACL reconstruction by preserving-remnant can promote the healing of the ACL grafts, compared to ACL reconstruction by removing-remnant, it has a much batter clinical prospect. |
