Fixator for vertebra stabilising with two pediculus screws - has two ellipsoidal nuts, and axially symmetrical recess in pediculus screw head

摘要

The pediculus screws have slotted heads. The fixation contains a threaded rod with smaller thread dia. than the screw head slot width. Nuts are screwed on the rod for fixing in the screw head slots. The nuts are ellipsoidal, and the screw head has a recess for the nuts. Pref. the rod thread-free part has an ellipsoidal thickening. The screw head recess is cylindrical and has a dished or frusto-conical configuration at the crew head bottom. The recess typically has a champer and an inner thread for closure screw with undercut head. ADVANTAGE - Reduced rotation and compression-tensile variable load during growing into the bone tissue.