Bone fixation apparatus

A surgical spinal fixation system (10) includes a bone bolt (11) having first end portions (13) that are adapted to be surgically implanted into a patient's spine (S) at first and second spaced apart positions and a central portion (15) of the bone bolt (11) defining a load transfer surface, the bone bolt (11) having a second upper threaded sections (14) for threadably receiving a nut (31) at a shaped, countersunk interface (32). As an alternate embodiment, a bone screw (45) provides an upper enlarged head (48) with a lower coarsely threaded (47) shank (46). A plate (17) having upper (17A) and lower (17B) surfaces and outer opposed edges is provided with an elongated slot (20) for accommodating a selected bone bolt (11) or bone screw (45). The plate edges carry fine adjustments (27,28) extending between the upper (17A) and lower (17B) surfaces of the plate (17) and a load transfer washer (35) interfaces the plate (17) and the selected bone bolt (11) or bone screw (45) for distributing load (and reducing stress) from the bone bolt (11) (or screw (45)) to the plate (17).