To observe the histology change of the insertion using different diamertrical bone tunnel in anterior cruciate l igament (ACL) reconstruction. Methods Ninety Japanese rabbits were selected, wihout female and male l imit, weighing 2.5-3.0 kg, and were randomly divided into 3 groups, 30 in each group. The ratio of transplantation l igament diameter and bone tunnel diameter was 1/1 (group A), the ratio was 1/1.5 (group B), and the ratio was 1/2 (group C). Bone tunnel observation and histology observation were carried out in the 4th, 8th and 16th weeks postoperat ively. Results Wound healed well in 3 groups. The mean time of walking functional recovery was 1.5, 2.0 and 3.5 days in groups A, B and C respectively. After 4 weeks of operation, more soft tissues at tunnel entry were observed in group A and group B than in group C; after 8 weeks of operation, there was no crevice at bone-tunnel entry of the groups A and B, there was no improvement in group C; after 16 weeks of operation, groups A and B showed the normal insertion, group C had no normal insertion. Histology observation: in groups A, B and C, bone-tunnel was filled with loose connective tissue after 4 weeks of operation; group A and group B emerged the discontinuation ACL insertion tidal l ine after 8 weeks of operation, group C had no insertion; groups A and B emerged the similarity normal ACL insertion tidal l ine structure after 16 weeks of operation, but group C had no this structure. The results of ultimate tensile strength in groups A, B and C were (75.44 ± 7.06), (91.37 ± 6.14) and (126.91 ± 4.61) N respectively at 4 weeks; the results were (74.31 ± 4.81), (88.30 ± 7.46) and (124.34±8.44) N respectively at 8 weeks; and the results were (62.20 ± 5.32), (71.53 ± 5.99) and (83.62 ± 5.69) N respectively at 16 weeks. There was no significant difference between group A and group B (P gt; 0.05), and there were significant differences between groups A, B and group C (P lt; 0.05). Conclusion In the ACL reconstruction, the ratioof transplantation l igament diameter and bone tunnel diameter being 1/1.5 will not affect the insertion outcome, but if theratio less than the l imit it will affect the insertion outcome.
ObjectiveTo investigate the effects of different concentrations of osteoprotegerin (OPG) combined with deproteinized bone (DPB) on the bone tunnel after the anterior cruciate ligament (ACL) reconstruction. MethodsThe femoral epiphyseal side was harvested from newborn calf, and allogenic DPB were prepared by hydrogen peroxide-chloroform/methanol method. Then, DPB were immersed in 3 concentrations levels of OPG (30, 60, 100 μg/mL) and 3 concentration ratios (30%, 60%, 100%) of the gel complex were prepared. Sixty healthy New Zealand white rabbits, male or female, weighing (2.7±0.4) kg, were divided randomly into 4 groups (n=15):control group (group A), 30% (group B), 60% (group C), and 100% (group D) OPG/DPB gel complex. The ACL reconstruction models were established by autologous Achilles tendon. Different ratios of OPG/DPB gel complex were implanted in the femoral and tibial bone tunnel of groups B, C, and D, but group A was not treated. The pathology observation (including the percentage of the femoral bone tunnel enlargement) and histological observation were performed and the biomechanical properties were measured at 4, 8, and 12 weeks after operation. ResultsOne rabbit died of infection in groups A and D, 2 rabbits in groups B and C respectively, and were added. General pathology observation showed that the internal orifices of the femoral and tibia tunnels were covered by a little of scar tissue at 4 weeks in all groups. At 8 weeks, white chondroid tissues were observed around the internal orifices of the femoral and tibia tunnels, especially in groups C and D. At 12 weeks, the internal orifices of the femoral and tibia tunnels enlarged in groups A, B, and C, but it was completely closed in group D. At each time point, the rates of the femoral bone tunnel enlargement in groups B, C, and D were significantly lower than that in group A, and group D was significantly lower than groups B and C (P<0.05); group C was significantly lower than group B at 8 weeks, but no significant difference was found at 4 and 12 weeks (P<0.05). Hisological observation showed that fresh fibrous connective tissue was observed in 4 groups at 4 weeks; there was various arrangements of Sharpey fiber in all groups at 8 weeks and the atypical 4-layer structure of bone was seen in group D; at 12 weeks, Sharpey fiber arranged regularly in all groups, with typical 4-layer structure of bone in groups B, C, and D, and an irregular "tidal line" formed, especially in group D. Biomechanics measurement showed that the maximum tensile load in group D was significantly higher than that in groups A and B at 4 weeks (P<0.05), but no significant difference was shown among groups A, B, and C, and between groups C and D (P>0.05); at 8 weeks, it was significantly higher in groups C and group D than group A, and in group D than group B (P<0.05), but there was no significant difference between groups A, C and group B (P>0.05); at 12 weeks, it was significantly higher in groups C and D than groups A and B, and in group D than group C (P<0.05), but difference was not significant between groups A and B (P>0.05). ConclusionDifferent concentrations ratios of OPG/DPB gel complexes have different effects on the bone tunnel after ACL reconstruction. 100% OPG/DPB gel complex has significant effects to prevent the enlargement of bone tunnel and to enhance tendon bone healing.