| Objective To explore effects of local administration rhBMP-2/rhVEGF165ontendon-bone early healing after anterior cruciate ligament reconstruction in rabbits.Methods Seventy eight healthy male adult New Zealand white rabbits, weighting2.0～2.8kg，averaging2.4kg，were randomly divided into Group VB，B，V，F andnormal group. Each group had18rabbits in the first four groups and normal group had6ones. Bilateral anterior cruciate ligaments of each animal were removed andreconstructed with autogenetic tendon of semitendinosus muscles while normal groupdid not receive any operation. The fibrin glue (FG) containing rhBMP-2/rhVEGF165was injected into tendon-bone interface of Group VB. FG with rhBMP-2was injectedin Group B, FG with rhVEGF165in Group V and only FG were used in Group F. Nointervention was given in the normal group. Six animals in each group were sacrificedrandomly in deep general anesthesia with an overdose of Pentobarbital sodium at the2nd,4th,8th postoperative week respectively. Right knee specimens were harvested,fixed, decalcified, embedded in paraffin and sectioned, then stained withhematoxylin-eosin, and examined under microscopes. Left knee specimens werefrozen（-80℃）until biomechanical testing. The specimens were thawed at roomtemperature before biomechanical testing. The specimen was affixed to an InstronE3000mechanical testing system to determine the average maximum load (in Newtons)and stiffness (in Newtons per millimeter). Results Histological examination showed that after two weeks of operation, the tendon and bone was connected tightly withactive proliferation of fibroblast in Group VB; Some chondrocytes were observed inthe tight interface of Group B; The interfaces of Group V and F consisted primarily offibrovascular tissue with loose connection. After four weeks of operation, the interfaceof Group VB initially formed four-layer insertion: collagenous tendon, uncalifiedfibrocartilage, calcified fibrocartilage and bone, while those of Group B, V and Fcomposed mainly mature fibroblasts with tight connection and a certain osteogeneticreaction was observed in the bone tunnel wall. After eight weeks of operation, therewas more obvious four-layer insertion with tidemark in the interface of Group VB andosteogenetic reaction further progressed in the bone tunnel wall in Group B. The widthof tendon-bone interface of Group V and F narrowed further and the number offibroblasts significantly reduced. Biomechanical analysis displayed that there was nosignificant difference with regard to the average maximum load and stiffness amongthe first four groups at the2nd week postoperatively(P>0.05).Not until4th and8thweek after operation, were the average maximum load and stiffness of Group VBhigher than those of Group B, V and F (P<0.05). Meanwhile, the average maximumload and stiffness of Group V and B were better than those of Group F (P<0.05).Conclusions Combined administration rhBMP-2and rhVEGF165can enhancetendon-bone early healing after anterior cruciate ligament reconstruction in rabbits andthe effects of combination are stronger than that of single use. |
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