US Patent 9474558 Bone plate with screw hole arrangement

An orthopedic screw system includes a screw with a locking head that can both lockingly engage in a fixed angle threaded screw hole to secure a plate to a bone without compression, and non-lockingly engage at a compression screw hole to provide compression between the plate and the bone. The structure of the system is particularly well adapted to plates and screw of small dimensions, such as screws smaller than 3.5 mm and is capable of providing high compressive force, on the order of 120 lbs of axial load, without significant plastic deformation between the screw and plate. Further, the screw holes are structured for arrangement in tight clusters on the bone plate, thereby facilitating a compact design on the bone plate.