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Spinal Pedicle Fixation Revisited: The Role of X-rays and Other Surgical Factors

Study Design. In this latest article in the Journal Club series, we revisit a classic Spine article that addressed many of the challenges associated with the early use of pedicle screw instrumentation. Objectives. To identify the relevant strengths and weaknesses of this study, and review ways that the results have influenced the field of spine surgery and stimulated further research endeavors. Summary of Background Data. Pedicle screw fixation has rapidly become one of the most popular strategies for achieving a solid fusion of the thoracolumbar spine. Because placement of pedicle screws is associated with specific potential complications, traditional navigational techniques such as intraoperative radiographs, fluoroscopy, and intraoperative electrophysiologic monitoring have long been used to assist screw insertion and assess final positioning; however, in some instances, the reliability and validity of these techniques have remained suboptimal. Weinstein et al examined the reliability and validity of plain radiography for evaluating transpedicular instrumentation, and also attempted to define the relationships between various surgical factors and successful pedicle screw placement. Methods. The study was reexamined from a modern perspective to acknowledge its limitations as well as recognize the enduring impact its results have had on the field of spine surgery. Results. Although there are some minor flaws, the general design of this study is sound. The investigators confirmed that radiography is not reliable for assisting with pedicle screw placement or evaluating the status of fixation, indicating that adjunctive techniques are needed to improve the accuracy and safety of this procedure. Other than an appreciable benefit associated with practice, the rate of successful pedicle screw insertion proved to be independent of all other surgical factors, which the investigators interpreted as evidence that transpedicular fixation is technically demanding and requires specialized training. Finally, the Weinstein approach to pedicle screw insertion was recommended in the lumbosacral spine because it spares the facet joint of the superior motion segment that is not included in the fusion, acting as a potential safeguard against adjacent segment degeneration. Conclusions. Despite its weaknesses, this study should be considered a landmark article with considerable historical significance. The concepts regarding pedicle screw instrumentation revolutionized spine surgery and forever changed the ways in which surgeons address spinal pathology. Future research should be directed toward developing more effective adjunctive techniques that will serve to improve the safety and consistency of transpedicular fixation.