| AO principle requires complete anatomical reduction for bone fracture, which make surgery large invaded and functional recovery longer. BO principle leans to foucus on the biomechanical character, which make the surgery less invaded, and functional recovery sooner. However, the BO principle is not well known for the veterinarians in China. The purpose of this study is that the external skeletal fixation and the "Tie-in" construction were used for tibial fracture fixation compared with traditional intramedullary pin fixation in the respect of imageology, biomechanics, biomechemitry and histology in order to providing for evidences of clinical application.Experiment I The Establishment of External Skeletal Fixation and "Tie-in" TechniqueObjective:Probe to apply external skeletal fixation and "Tie-in" technique. Method:12adult healthy exoerimental dogs were divided into Group A, B, C in which each group was4dogs. A and B were experimental groups treated with the external skeletal fixation and "Tie-in" fixation, respectively. Group C was control treated only with intramedullary pin fixation. Result:The technical gists of external skeletal fixation and Tie-in were operated masterly. Group A spened the longest operation time, group B was second and group C the shortest. However, the difference were insignificant (P>0.05). The fixator of group A and B were removed on the45th days after operation, therefore the cure time for group A and B were45days. By that time, all the anmials in those groups could walk normally. But the animals of group C had too little callus to remove intramedullary pin even at the end of the experiment. Thus, the cure time for group C was much longer than group A and B. The site of fixation pin was infected common after operation, which was25%in group A and100%in group B since fixation pins were used only in these groups. But the treatment of this complication was easy. Conclusion:The healing time for group A and B were much shorter than group C; pin site infection were common complication after operation, but was easy to handle with proper nursing.Experiment II Clinical and X-ray Comparason of External Skeletal Fixation and Tie-in Strcture with Intramedullary Pin in Tibial Fracture in DogsObjective:Clinical effectiv comparison of external skeletal fixation and "Tie-in" constructure (external skeletal fixation+intramedullary pin) with intramedullary pin fixation in the tibial fracture in dogs. Method:12adult healthy experimental dogs were divided into Group A, B, C in which each group was4dogs. A and B were experimental groups treated with the external skeletal fixation and "Tie-in" fixation, respectively. Group C was control treated only with intramedullary pin fixation. After operations, the functional recovery of operated limb, that is the severity of lameness were scored at set time and the criterion. The callus formation and density in junction sites of bone fractures was examinated with X-ray every2weeks for evatuation of bong healing. The infection of pin tracks and loosening of fixation pins were examinated for evaluation of postoperative complication and difficulty of nursing. Result:The postoperative valuation of limb functional recovery indicated group A scored2.0at week2and0.75at week6, while the other groups still scored about3.0at week6, so group A showed significant difference (P<0.05) comparing with group B and C at week2-6; group B scored0at week9after fixation removal at week6, which meant normal limb functional recovery, at that time group A and C scored0.25and0.75respectively, group B had significant difference(p<0.05)compared with the other groups. The result of X-ray examination indicated group A scored2.75,1.5,0.25at week2,6and12, respectively, while group C scored4.0,3.0,1.75, group A had its surperiority in bone healing, and significant difference (P<0.05) compared with group C. there were insignificant difference (P>0.05) of X-ray sciores between group B and C before week10, but at week10and12, group B got back to normal faster that scored0.25and0, respectively, while group C scored2.0and1.75, significant difference (P<O.O5) was showed between them; group A and B had insignificant difference (P>0.05) during the whole experiment. After operation, complication in group A and group B indicates25%and100%, respectively. In group B,1pin only loosed, and other pin tracts had slight infection. Nursing was basically easy, and the operative time and blooding during operation were relatively shorter in the external skeletal fixation and "Tie-in"+intramedullay pin fixation than internal fixation. Conclusion:Group A had great advantage in bone healing and functional recovery especially in early period, but "Tie-in" provided effective fixation which made it recovered sooner after pin removal.Experiment III Biomachenical and Histological Comparason of External Skeletal Fixation and Tie-in Structure with Intramedullary Pin in Tibial Fracture in DogsObjective:To compare external skeletal fixation and Tie-in structure with intramedullary pin in the respect of biomechanics, serum ALP and histology for providing comprehensive evidence for the superiority of external skeletal fixation. Method:12adult healthy experimental dogs were divided into Group A, B, C in which each group was4dogs. Group A and B were experimental groups treated with the external skeletal fixation and "Tie-in" fixation, respectively. Group C was control treated only with intramedullary pin fixation. The biomechanical test is to test the mechanical character is the directest way to value the level of bone healing. After euthanasia from dogs operated at set time, the repaired tibia put on the universal testing machine, and underwent a break test. Blood samples were collected every2weeks, and tested by serum biochemistry machcine for ALP level. And the bone samples were collected from fracture line was fixated, embed and made into section with sclerous tissue microtome for histological examination. Result:The biomechanical testing result indicated insignificant difference among these groups (P>0.05). The ALP testing result indicated at most of the time, there was insighificant difference among these groups, except at week2, group C reached a summit at92.1, which showed significant difference (P <0.05) comparing with the other groups. Histological results indicated that osteoblasts obviously increased and bone trabeculae were arranged trimly in fracture line and bone fragments was connected closedly in group A and B since there was stress stimulation from an early period; but in group C, the bone facture line was filled with cartilage cells mainly, bone fragments connected porosely and bone healed slowly since intrmedullary pins were not kept aganst shearing force. Conclusion:the external skeletal fixation and "Tie-in" demonstrated obvious promotion of bone healing, while bone healing effect of the external skeletal fixation is better than that of Tie-in". Both excelled intrmedullary pin structure. |
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