US Patent 8449585 Semi-constrained bone screw

A bone screw for attaching a bone plate to bone includes a shank defining a lumen extending at least partially therethrough from a proximal end thereof, a head defining a lumen therethrough, and a rod member. The rod member is configured for insertion through the lumen of the head and into the lumen of the shank. The rod member is fixedly engageable with the shank and moveably coupled to the head such that both the rod member and the shank are moveable with respect to the head.