Design of micro-motion locking nail and application in weight-bearing bone defect model in goats

[Objective]To design a new micro-motion locking nail and use it in the weight-bearing bone defect models in goats.[Method]The contours of humerus and femur of twelve goats were observed,and the anatomical parameters including curvature and diameters of proximal,middle and distal femur were measured respectively.According to the anatomical parameters,a new micro-motion locking nail was designed and the segmental bone defect models of femur were prepared with a new interlocking bone nail in 8 goats,and the effects of the model were also evaluated.[Result]The contours of femur were similar to the ones of human,the length and the front curvature of femur were(13.2±0.83)cm and(9±1.22)°.The proximal,middle and distal diameters of fumer were(12.7±0.35) mm,(12.3±0.21)mm,(12.7±0.33)mm respectively.There weren't significant difference between them.The length and diameter of new micro-motion locking nail were 125 mm and 9 mm.There were two locking hole in the proximal and distal nail,which diameters were 4.0 mm and 5.5 mm,the diameter of locking nail was 4 mm.There were no inter fixation failure in the 8 goats with segmental bone defect of femur at 4 and 24 week postoperation.And the maximal anti-pressing strength was more than 5 000 N,which was 20 times of weight of goat,and the length of micro-motion was 0.7～1.4 mm under 50～400 N axial compression.[Conclusion]The new micro-motion locking nail can produce micro-motion under axial compression,which can be used of fixed bone defect of femur in goats.