A polyaxial locking screw system includes a bone plate defining a plate hole with an inner spherical surface and a relatively harder split polyaxial bushing with a outer spherical surface provided within the plate hole for receiving a bone screw. In one embodiment, the plate is formed from titanium alloy, while the bushing is formed from a cobalt chrome alloy. The outer surface of the polyaxial bushing includes a plurality of spikes. When the screw is inserted into the bushing, since the bushing material is considerably harder than the plate material, the forceful expansion of the bushing during screw insertion causes the spikes to penetrate into the inner spherical surface of the hole, thereby increasing the frictional engagement of the bushing to the plate to lock the screw at a desired angle.