ABSTRACT
Objective To observe destruction of tibias created in ablating of the swine limbs in vivo with radiofrequency,the influence on the surrounding organization structure,and the repair process of lesions for treating bony tumor.Methods There were eight pigs included in the first part of the experiment.RFA was performed under DSA guidance at the same position of the diaphysis and the upper end of their right tibias in hind leg during anesthesia,then X-ray and CT examinations were performed at different time points after RFA,and subsequently the pigs were executed by depth anesthesia.Control specimens,specimens of the immediate time,the third day,the tenth day,the twenty-fourth day,the fifth week,the eighth week,the twelfth week after RFA were obtained at the diaphysis and the upper end of their tibias.X-ray and CT examinations of these specimens were performed.These specimens were observed both by naked eye and under microscope.The observation included the general state of the laboratory animals after RFA,the configuration of RFA lesions in the gross specimen and the corresponding histologic changes,the boundary of necrosis in RFA lesions and the corresponding boundary of the gross specimen.There were sixteen pigs in the second part of the experiment.RFA was performed at the same position of the diaphysis and the upper end of their right and left tibias in hind leg during anesthesia,and the pigs were immediately executed by depth anesthesia after RFA to get thirty-two capitulum specimens and thirty-two diaphysis specimens.The scope of necrotic tissue in RFA lesions was observed and measured.The border and scope of necrotic tissue in RFA lesions were observed.Major axis,minor axis,and necrosis volume were measured.The independent sample t test was employed to compare the volume of necrotic tissues between capitulum and diaphysis.The one sample t test was employed to analyze volume of necrotic tissue among capitulum,diaphysis and the standard data.Results No accidental death of the animals occured in the first experimental.The loss of neurological function of the hind leg did not happen.Coagulation necrosis in cancellous bone of capitulum and marrow of diaphysis lesions created in ablating was observed.On 3th to 10th day after RFA,inflammatory cells infiltrated in hemorrhage tape and then granulation tissues formed.Granulation tissues replaced necrotic bone gradually from outside to inside.Low density band was showed on images of X-ray and CT examination in the specimen of 10th day,and it extended inward.The immature bone was observed in fibrous tissue sited at the edge of lesions,which appeared as sclerosis on X-ray and CT examination.The scope of necrotic tissue in RFA lesions included coagulation necrosis and hemorrhagic zone of its periphery.The dead bone and secondary pathological fracture appeared in two of eight pigs.RFA hardly damaged compact bone in the diaphysis,but the damage of soft tissue was observed outside the compact bone.In the second experiment,the shape of lesions in cancellous bone of capitulum was ellipsoid,with long axis of(2.59±0.21) cm,minor axis of(2.15±0.10) cm,and volume of(6.34±0.27) cm3.The shape of lesions in the diaphysis of tibias was ellipsoid,with long axis of(4.53±0.20) cm,minor axis of(1.71 ±0.22) cm,and volume of(7.14±0.36) cm3.There was significantly difference of necrosis volume between the capitulum and diaphysis lesions,(t=2.011,P＜0.05).The virtual necrosis volume of the capitulum and diaphysis lesions was significantly different from the presumed volume with RFA instrument(t=-613.371,-295.878,P＜0.01).Conclusion Cancellous bone of the capitulum can be damaged by RFA,but the compact bone of the diaphysis can hardly be damaged.The intact compact bone can be helpful to protect the surrounding soft tissues.X-ray and CT examination can be used in the evaluation of curative effect of RFA for treating bone tumors.Pathological fracture of the diaphysis may appear after RFA.