| ObjectiveFinite element analysis was used to measure the mutual displacement between the transporting bone block and the thick osteotomy end after the osteotomy during the bone transport operation to evaluate the influence of the number and layout of the half nails in the Ilizarov bone transport frame on the repair of tibial bone defects.Methods1.The calf of a male volunteer was scanned by dual-source spiral CT,and the data obtained was imported into the Mimics software to establish a normal three-dimensional model of the tibia.2.2.The establishment of tibial bone defect and the placement of the half-nail in the bone transport block follow the unified naming method for the unified designation of external fixation(MUDEF).In this naming method,for the division of limbs,each segment of the limbs is vertically divided into 8 equidistant basic planes(Ⅰ～Ⅷ);for the division of limbs,the cross section of each plane is divided into size The same 12 sectors are similar to the clock dial,and each sector is represented by channel 1 to channel 12.In this experiment,we studied the bone defect of the lower segment of the tibia,so the VI and VII layers of the tibia were selected as the tibial osteotomy line in the Solidworks software to construct a 5cm defect tibial bone defect model.On this basis,an osteotomy line with a thickness of 1mm was made 0.5cm below the tibial tubercle to form a bone transfer section,and finally a complete tibia bone defect bone transfer model was formed.According to the designed 11 ways of inserting the upper half nail of the bone transporting bone block,11 models of the Ilizarov bone transporting frame for the treatment of tibial bone defects were established.The half nail was selected according to the reference channel of the MUDEF when the bone transport section was placed.Channel 1,2,11,12.3.In Ansys 2017 software,finite element analysis was performed on 11 Ilizarov bone carrier models for treating tibial bone defects,and the displacement of each node on the osteotomy line of the tibial bone carrier segment in the standing position was measured.The larger the average displacement,the worse the fixation effect.4.Use SPSS 19.0 statistical software,use t test to compare whether there is a difference in the fixed effect,P<0.05 indicates that the result is statistically differentResultsOne half nail is placed in the first channel of the fourth layer(2.005±0.008)mm,one half nail is placed in the second channel(2.165±0.007)mm,and one half nail is placed in the 11th channel(1.802 ± The displacement of 0.009)mm and a half-nail(1.673±0.009)mm in the 12th channel was less than that of(5.9708±0.014)mm without the half-nail,and the difference was statistically significant(P<0.05);The displacements of the four models each containing a half nail are compared with each other,and the difference is statistically significant(P<0.05).One of the half nails has the largest displacement when placed in the second channel,and the other half nail is placed in the first channel.The displacement of insertion is the second,and the displacement of a half nail inserted in the 12th channel is the smallest.Two half nails are placed in(1.126±0.009)mm in the 12th and 1st channels of the fourth layer,two half nails are inserted(1.147±0.008)mm in the 12th and 2nd channels,and two half nails are placed in the 12th and 11th channels.The displacement of the channel is(1.041±0.009)mm.Two half nails are placed in the 11th and 1st channels of the fourth layer(1.111±0.008)mm,and the two half nails are placed in the 11th and 2nd channels(1.160±0.006)mm.The displacement of(1.307±0.007)mm with two half nails placed in the first and second channels is less than that of(1.672±0.008)mm when one half nail is placed in the 12th channel,the difference is statistically significant(P<0.05);Comparing the displacements of the 6 models with two half nails each,the difference is statistically significant(P<0.05).Among them,the displacement of the two half nails placed in the first and second channels is the largest,and the two half nails are placed on the 12th and 11th channels.The displacement of the channel is the smallest.ConclusionsWhen the Ilizarov technology is used to repair tibial defects,when the number of half nails is the same,the layout of the half nails,that is,the placement position,has an impact on the stability of the bone transport block.In the selection of the number of half-nails,more half-nails are selected to improve the stability of the bone transport block according to the fracture position and other objective factors. |
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