Patent ID: 7905909

Claim:
A bone fixation system, comprising: a) a titanium bone plate having at least two screw holes, each provided with an internal thread defining a screw hole axis; b) a cobalt chrome screw having a head and a shaft, said head tapered and including external two-start threads starting 180° apart, and said shaft has a first outer diameter with a reduced portion with a smaller second outer diameter that is spaced apart from and located between both said head and an opposite end of said screw, wherein said cobalt chrome screw can self-tap into said internal thread at an oblique angle relative to the screw hole axis to secure said cobalt chrome screw to said bone plate; and c) a titanium screw having a head a shaft, said head having threads that threadably engage with the internal thread so that the titanium screw secures to the bone plate along the axis of the screw hole axis to secure said titanium screw to said bone plate, said shaft of said titanium screw has a third outer diameter, wherein the second and third outer diameters are selected such that the cobalt chrome screw can carry a load no greater than the titanium screw.