The biomechanical comparison of helical plate and straight plates

Plates have been used for internal fixation for more than a hundred years. Although first problems, such as corrosion and insufficient strength have been solved, it cannot be said that the designs which have been presented recently have solved all the problems.In this study, we have aimed to compare the biomechanical characteristics of helical plates, which is one of the new methods in fixating spiral and oblique fractures, with straight plates. The comparison groups have consisted of two different fracture type that have been fixed by two different plates. Eighty four sheep tibias have been obtained and they have been divided into four groups (n=21). Tibias in first group were fixed by straight compression plate making transverse fracture. Tibias in second group were fixed by straight compression plate making 45° of oblique fracture. Tibias in thirth group were fixed by helical plate making transverse fracture. Tibias in fourth group were fixed by helical plate making 45° of oblique fracture. Each group has been divided into three subgroups (n=7) and axial compression, bending and torsion tests have been applied each subgroup.In axial compression test, statistically significant differences between transverse fracture and oblique fracture have been detected in both plate fixation. When the values obtained from three point bending test have compared to designated groups, statistically significant differences between straight plate and helical plate fixations have been detected. When the values obtained as a result of torsion test have compared between determined groups, statistically significant differences have been detected between straight plate end helical plate, which have been applied each fracture type.In the light of the data that we have obtained as a result of our work; helical plate fixation in use provided maximum torsion stiffnes and flexible system in case of axial compression and bending load.Keywords: Plate osteosynthesis, helical plate, biomechanic.