Fatigue evaluation of the Synthes cervical vertebrae plate and the Synthes anterior cervical vertebrae plate

Two Synthes cervical spine plate designs were evaluated in single cycle bending and fatigue. The Synthes CP titanium anterior cervical vertebrae plate commonly referred to as CSLP was evaluated with three different screw types while the Synthes 316L stainless cervical vertebrae plate commonly referred to as OROZCO was evaluated in the same manner with one screw design. Single cycle bending was performed on three plates of each type using one screw type design. Fatigue testing was performed at 5 Hz in ambient air on each of the constructs and corresponding screw types. Bending strength and bending rigidity were calculated from the load vs. deflection plots of the single cycle testing. The general shape of the S/N curve was defined based upon number of cycles to failure at incremental load values. Examination of the data and plots revealed a difference between the stainless plate and the titanium plate. The CP titanium plate with each screw type proved superior to the stainless plate under the conditions tested. Scanning electron microscopy was performed to ascertain the mode of fracture.