Screw Fixation In Spine Research Articles

The indications to perform a lumbosacral fusion and the subsequent clinical outcomes are topics of debate. There are a multitude of factors that affect outcome. The use of instrumentation to reduce the need for postoperative external immobilization and bed rest through immediate stabilization of the spine is attractive. The use of instrumentation also may improve the fusion rate. Since the 1940's, vertebral screw and pedicle screw fixation have evolved and become increasingly popular among spine surgeons. Both methods are designed to provide immediate stability and rigid immobilization of the spine without sacrificing additional motion segments required by other forms of conventional instrumentation (e.g. Harrington, Luque). Pedicle screw fixation has the additional benefit of generally not requiring the presence of intact laminae, facet joints, or spinous processes. The history of vertebral screw fixation dates back to 1944. King first described the placement of screws (three-quarters of an inch for women; one inch for men) parallel to the inferior border of the lamina and perpendicular to the facet joints of lumbar vertebrae in an attempt to avoid postoperative external immobilization and prolonged bed rest (Figure 1).2627 However, patients were encouraged to stay in bed for three weeks following surgery. A pseudarthrosis rate of approximately 10% was reported in patients fixed with screws and grafted from L5-S1. One (2.3%) patient experienced "nerve-root irritation" as a result of a poorly positioned screw which was subsequently removed.