Experimental Study Of A New Type Of External Fixation Device For Tibial Fracture

BackgroundTibial fractures are very common in clinical and battlefield treatment.The traditional treatment methods(non-surgical treatment,internal fixation and external fixation)each have their own advantages and disadvantages.For complex fractures and severely damaged fractures of the tibia,it is considered to use external fixation devices for one-stage or final treatment,which is particularly important in modern warfare with mass casualties,poor conditions,and combined injuries.However,the traditional external fixation system has many disadvantages such as inconvenience,easy loosening and risks of nail infection and delayed healing after surgery,which makes the applications of external fixators limited.Internal fixation plates as external fixators has the advantages of small size,light weight,convenient operation,and has been partially applied in clinical practice.However,it has not been further promoted because of its decreased overall mechanical stability.Secondly,the development of new types of external fixation was also carried out at home and abroad,including the Croatian CMC system,the Hoffman series in the United States,and the new-style unilateral integrated external fixator.But these systems still have the disadvantages of the traditional treatment methods.Our study project Clinical Verification and Transformation of Fully-Automated Field External Fixation System(2016TM-003)is aim to solve this problem.This article is a part of the planning and a preliminary study of the project.PurposeDesign a new type of external fixation device that is small in size,high in strength,convenient in operation,and capable of achieving the mechanical requirements for fracture healing.Verify the rationality and effectiveness of the device,and analyze the advantages and disadvantages of the external fixation device in the fixation of tibial fractures.MethodA.The finite element software(Ansys)was used to simulate the new external fixation device to verify whether the mechanical properties of the device meet the fracture healing requirements.At the same time,animal experiments were performed to verify the clinical feasibility of the fracture treatment.B.The mechanical characteristics of four types of tibial fracture fixation devices were tested in groups.And the compression,torsion,fatigue and maximum load tests were performed separately.Data were collected and statistical analysis was performed to verify whether there were statistical differences between the four groups.ResultsA.The results of the new external fixation device in finite element analysis showed that the displacement of the broken bone under a load of 700 N was 0.936 mm and the maximum stress of the device was 189 MPa,which met the mechanical requirements.In the animal experiment,the tibial fracture was healed after 2 months;B.A comparison of the mechanical tests showed that the compression stiffness was greatest in the LCP group(C),followed by the new device group(A),and the LCP external group(B)and the external fixator group(D)were the smallest and not significant(P=0.313);the torsional stiffness was compared in four groups(D>A>C>B),and had statistically significance in multiple comparison(P<0.05).There was no failure in fatigue tests.In maximum load test,the ultimate loads of four groups were measured(A>C>D>B),and all fixed models showed varying degrees of damage failure.ConclusionsThe new external fixation device for tibial fracture is well-designed to meet the fracture healing requirements.It has certain advantages in comparison with other fixation methods and can be used as a new method for the treatment of tibial fractures.