The Rapid Development for the Plastic Spanning Type Wrist Fixator

[[abstract]]Wrist fixators have already been applied to all kinds of fracture of the wrist joints extensively. They are one of the methods to maintain reconstructive position. The conventional gypsum treating usually coalesces in the incorrect position and has the disadvantage of ankylosis after coalescence. Wrist fixators provide the stability and adjustability and make the patients recover and restore well quicker. Wrist fixators include non-spanning configuration and spanning configuration which is applied to common Distal-Radius-Fracture of all kinds of wrist fractures. The regular apparatus material on the market nowadays is metal. Surgeons can’t be completely benefited from the X-ray photo because of the translucent ability of the fixator’s material. The main objective of this research is to design the plastic spanning wrist fixator. The advantages of the new-designed plastic spanning wrist fixator are not only the functional stability and adjustability, but also X-rays transparence. Moreover, the plastic produce will be easy to be mass production. Referring to current clinical products, which are TRAUMA-FIX S-20 and the wrist fixator invented by Dr. Jinn Lin in Taiwan, they have telescoping shaft for adjustability and ball joints for 3 axis motion, These functions prevent the sequelae of ankylosis after coalescence. In order to accumulate the speed of product development process, the state of the art technologies, which are CAD, CAE, and Rapid Prototyping (RP), have been integrated and used in this research. CAD can aid designer for dimension redefined. CAE can shorten products construction period and reduce the cost by simulate experiment in computer which was taken by material testing using real mode. RP technology can turn designs to physical models and check the kinetic interference and the blind spots of designs. The stability of the plastic wrist fixator has the relation with the displacement results of CAE. The anticipative results on CAE is that the less displacement emerge under the range of force. In this research, Design-1 and Design-2 are new-innovated plastic spanning wrist fixators. According to the suggestions from the CAE results, dimensions have been modified to give enough structural reliability. Design-1 and Design-2, which are plastic material of PC and ABS, haven’t exceeded the yield strength under the range of force by analytic software of CosmosWork. According to the kinetic prototype by RP technology, New Design, which is integrated all of the advantages of previous designs in terms of the mechanism, has been introduced. The material is suggested to use PC+30%G.F plastic for better mechanical properties. The CAE shows the displacement at the dedicate location when the force is 30N is 1.3mm. The displacement of commonly used metal TRAUMA-FIX S-20 is 0.7mm. It shows the similar displacement of the above two and provides good satisfactions of the New Design. However, PC+30%G.F is one of the plastics usually used in injection molding and it is difficult to be used in cutting process. In order to fabricate a benchmark part for function testing, 80%PC+20%ABS was used. The disparity of the dedicate location between the simulation result and experimental data is only 0.3mm in 30N. It shows a good agreement of the New Design.