Screws placement effect on locking compression plate (LCP) for tibial oblique fracture fixation

摘要

One of the basic principles for internal fixation is the achievement of stable construct for proper bone healing. Locking compression plate (LCP) achieved it through locking screws that create a fixed-angle construct providing angular stability. The plate and screws combination to construct a stable fixation depends on factors such as the type of fracture and surgical preference. The optimum combination can provide optimum result in terms of achieving boney union. In this study, three combinations of screw placement with only one screw for each bone fragment for a fracture fixation construct using LCP were analysed via finite element method. Three dimensional model of a tibia and fibula were reconstructed from computed tomography image datasets, and an oblique fracture was simulated at the midshaft of the tibia. Eight-hole LCP was placed across the fractured line and three screws placement were simulated. The properties of bone were assigned with a stiffness of 17GPa and Poisson's ratio of 0.3, ligaments were modelled as rigid links, and load equivalent to three times the body weight was applied equally to the tibial plateau. Results showed that there placement of screws the closest to the fracture side will provide more stabiliy and less stress to the implant and the fracture construct itself. The results are unique to the simulated oblique fracture, and other types of fracture could also be analysed using the same method.