The Related Study On Revision Pedicle Screws

OBJECTIVE: 1) To describe a simple and fast technique for removal of deeply situated broken pedicle screw fragments ; 2) To evaluate the effect of change in screw dimensions and hole augmentation (matchstick bone; threaded Teflon anchoring-TTA) in pedicle screw revisions, the insertional torque and the axial pull-out strength were determined. And results were compared with those in control specimens in an vitro study using cadaveric thoracolumbar spines. Then, to determine the best method of salvage for failed pedicle screws by evaluating the insertional torque and pull-out strength after placing a larger diameter or longer screw into a stripped hole. Use of matchstick bone and use of TTA with original dimensional screws replacement were also investigated. Finally, the effect of insertional torque of simply removing and replacing a pedicle screw in its original hole was investigated.SUMMARY OF BACKGROUND: In the modern era of spine surgery, instrumentation is becoming increasingly commonplace. The pedicular portion of a vertebrae offers a strong point fixation, and thus transpedicular screws are used continues to improve in terms of surgical techniques as well as the technical quality of the instruments. Despite advance in the rigidity of transpedicular screw fixation system, hardware failures are still encountered . The resulting loss of fixation lead to fusion failure and poor surgical outcome, in cases in which the spinal segments again become unstable and misaligned, ex novo spinal stabilization should be undertaken . This implies the need for a minimally traumatic technique for the extraction of the screw fragments to retain the integrity of the pedicle for implantation of a new stabilization system. With regard to the techniques of revision pedicle screws, there are three options to be chosen by surgeon from: replacement of pedicle screws, augmented with pressurized or unpressurized PMMA; replacement with larger screws of a more aggressive design; or replaced with longer screws, engaging the anterior vertebral cortex. The potential for serious complications...