I have just returned from a trip to Austria to learn the technique of insertion of a transfacetal, transpedicular screw fixation for patients with severe back pain. The screw technique called PERPOS is interesting and has been applied for those patients (specially selected) who do not quite meet the criteria for pedicle screw fixation. This fuses the facets causing pain without interfering with the other joints. The procedure can also be reversed and converted to a pedicle screw fixation in the future if necessary. I like it. See the image above.
