Novel Fiber Based Temporary Semi Epiphyseal Plate Block Device

The semi-epiphysiodesis is an effective therapy for children with lower limb deformitydisease. The semi-epiphyseal plate block device which is used in correcting skeletal deformitieshas been successfully applied in clinical in the1930s. However, the temporary epiphyseal plateblock device used now is made of steel metal material. As we all know, metal dissociation is harmto human body. And due to high hardness of the steel material, this block device can’t attach thebone well so that the plate shape of the device and the appearance of the epiphysis can’t not fit inwell, which caused screw pull-out or fracture and difficulties in inserting and removing epiphysealplate. Ideal temporary semi-epiphyseal plate must have good mechanical property, dimensionalstability, flexibility, air permeability and biocompatibility.The fiber based temporary semi-epiphyseal plate block device has excellent mechanicalproperties, adjustability, tight attaching and good flexibility, so it is expected to replace thetraditional steel temporary semi-epiphyseal plate block device. However, the problem of how todesign the final knot of the fiber based temporary semi-epiphyseal plate block device, so that it canwithstand500N to1000N growth force is difficult to solve. Therefore, the goal of this paper is todevelop a type of soft artificial ligament tissue material to replace the traditional steel material.Through the structure design, production and post test, the research finally obtained the fiber basedtemporary semi-epiphyseal plate block device with good comprehensive properties.The test chose1600D high strength polyethylene yarns as the best braid materia ls throughreferring to the relevant literature and testing five high strength polyethylene yarn（single,400D,600D,1200D,1600D） which meet the requirements on preliminary strengthexperiment. And then, the study used textile braiding technique to design four kinds of fiber basedtemporary semi-epiphyseal plate block device, which were knitted open up temporary semi-piphyseal plate block device, knot type temporary semi-epiphyseal plate block device,8typetemporary semi-epiphyseal plate and O type temporary semi-epiphyseal plate block device. Thebraiding structure used4,6,8and10thread each of these four kinds of device. Then the paperreveals the influence of device structure and the amount of the yarn on the device geometry and mechanical properties of temporary semi-epiphyseal plate block, through the comparative analysisof the indexes of different yarn quantity with the same structure, and the longitudinal comparativeanalys is of different structure with same amount of yarn. These indicators include the thickness,diameter of the sample, elongation, elastic recovery, plastic deformation and creep properties andso on.This paper realized the alternative to the traditional steel material with flexible textile productof the temporary semi-epiphyseal plate block device from the optimization of textile structure,which including structure design, material selection, product manufactured and parameteroptimization. The paper draws the following conclusions:After testing the tensile strength and elongation at break of five kinds of high strengthpolyethylene yarns (single400D,600D,1200D,1600D), the paper finds that1600D high strengthpolyethylene yarn is the ideal material of the fiber based temporary semi-epiphyseal plate blockdevice which has the best performance on strength and dimensional stability of five kinds of yarn.Then design yarn with snagging resistance, braid them into rope. Comparing the strength of thesefive kinds of yarn with six thread each, finds that twist and strength of single yarn have a stronginfluence on the rope strength, that is to say, the smaller twist or bigger strength the yarn have willlead the rope having the bigger strength. And the more braided wire, the bigger rope strength, andthe variation of strength between4threads and6threads are more obvious than8threads.knitted open up temporary semi-epiphyseal plate block device is knitting with inverseweaving method, and it has no knot ladder during the stretching process. However, it does notmeet the expected design in the aspect of strength and the elongation is not stable. So this kind ofblock device does not meet the design requirements. Knot type temporary semi-epiphyseal plateblock device is based on the pre braided to form the rope and then knotted the rope. It can meetthe design strength requirements by change the knot material. As for the elongation, because itneeds two steps to complete, the elastic deformation rate is large. Actually, the elongation rate of4threads,6threads and8threads are all more than20%.8type temporary semi-epiphyseal plateblock device is winding with the shape number8using single yarn. Though, the elongation valueis a bit high, the other testing indexes are all meet the design requirements. The design of O typetemporary semi-epiphyseal plate block device is based on8type temporary semi-epiphyseal blockdevice. All parameters of the test indexes meet the design requirements.