System and method for bone fixation

Abstract

A system and method for maintaining positions of bones fixed or approximated relative to each other is provided that is ideal for minimizing interference with surrounding viscera in spinal column procedures, although other good application therefor are also disclosed. In the preferred form, a cable anchoring apparatus in the form of a screw member having an elongate shank that is threaded for substantially the full length thereof is employed. An internal driver surface is provided so that the size of the proximate end of the shank can be minimized or maintained consistently sized with respect to the reminder of the shank with no enlarged driver head formed thereat. This allows the amount of bone material that is removed from full insertion of the screw anchor to be minimized, i.e. no countersinking for an enlarged driver head is necessary, thus improving holding power of the cable anchor herein. Further, the full threading of the shank for substantially its entire length enables the screw member to be fully sunk into the bone so that no portions thereof, such as an enlarged screw head, project into the surrounding body cavity in which the bone is located. In the spinal column application, a criss-cross cable pattern is disclosed to better resist torsional forces and keep any decompression devices in place in the gap between adjacent vertebrae.