Biomechanical comparison of the controlled micromovement allowing plate with respect to the rigid plate ( A biomechanical study )

Screw plate combinations have been used for the treatment of bone fractures through the last century. In the last 20 years principles of surgical treatment of bone fractures have evolved through the understanding of fracture healing under different mechanical conditions and through material knowledge background used in fracture fixation. Specifically there are studies about positive effects on fracture healing of controlled micro-movement. However, there are as yet no definite known values concerning the amount of micro-movement permissible in the fracture line.But knowledge of data lacks for the amount of movement necessary beyond fracture line. In our study we aimed to design a controlled micro-movement plate which could also stabilize fractures functionally. Our aim is to consider the stability of the newly designed CMM plate.In this study we compared two differently designed plates which had 4 and 6 holes at each. Plates basically have two-part modularity in which one part fits into the other. Bone plate screw system movement was achieved through a string which was integrated in between the two modular parts. The spring used has been designed and produced through the use of Hooke?s law and necessary string diameter, wire diameter and number of wrapping were all calculated for the chicken bone experiment. For comparison of this design, a monoblock neutral plate made of the same material and size was designed and produced. Plates designed for chicken bone properties were applied for fixation after a transverse osteotomy done to the chicken femora. Neutral plates and CMMP plates stability parameters were compared in vitro biomechanically. Axial compression tests, torsion and three point bending tests were done to the plate-fixation- applied ostetomized bones.No statistical difference was found in axial compression tests. Three point bending tests revealed a statistical difference between the first group (n=6) (four hole neutral plate) and the third group (n=6) (six hole neutral plate) at 45 Nm force applied. Torsion tests revealed a statistical difference between the second group (four hole CMMP) (n=6) and the third group (six hole neutral plate) (n=6) at 2 N and 4 N torsional forces.Data obtained from these tests revealed that CMMP plates used were as stable as neutral plates under axial loadings. There is a lack of data about elastic system?s behavior used between modular parts of CMMP plates in living organisms. Therefore, there is a need for vivo animal studies with these newly-designed CMMP plates. CMMP plates could be the choice for calculating the amount of micro-movement necessary to obtain an ideal bone healing after a fractureKey words: Controlled micro motion plate, biomechanic, stability, elasticity, spring.