Comparative performance of a flexible fixation implant to a rigid implant in static and repetitive incremental loading

Four point bending tests under static and physiological repetitive loading were performed on two implant systems, one a rigid established plate system and the other a new flexible pin screw system. Both systems were made from stainless steel components. Under static loading the plate system had a higher ultimate yield and modulus of elasticity than the flexible pin screw system. Small repetitive incremental loading produced different results and showed that the flexible pin screw system had nearly always a higher ultimate yield point and a lower modulus of elasticity. This difference between the non-physiological static loads and the physiological repetitive loads indicates that the flexible pin screw system has the potential in certain situations to create more load sharing with the bone and hence a better fracture fixation system than the established plates and screws technique.