Health & Medical Neurological Conditions

Percutaneous Pedicle Screw Fixation

´╗┐Percutaneous Pedicle Screw Fixation

Abstract and Introduction

Abstract


Object. Standard techniques for lumbar pedicle screw fixation involve open exposures and extensive muscle dissection. The purpose of this study was to report the initial clinical experience with a novel device for percutaneous posterior fixation of the lumbar spine.
Methods. An existing multiaxial lumbar pedicle screw system was modified so that screws could be placed percutaneously by using an extension sleeve that would allow for remote manipulation of the polyaxial screw heads and remote engagement of the screw locking mechanism. A unique rod insertion device was developed that linked to the screw extension sleeves, allowing for a precut, precontoured rod to be placed through a small stab wound. Because the insertion device relies on geometrical constraint of the rod pathway through the screw heads, rods can be placed in a standard submuscular position with minimal manipulation, essentially no muscle dissection, and without the need for direct visual feedback. Twelve patients (six men and six women who ranged in age from 23-68 years) underwent pedicle screw fixation in which the rod insertion device was used. Spondylolisthesis was present in 10 patients and nonunion of a prior interbody fusion was present in two. All patients underwent successful percutaneous fixation. Ten patients underwent single-level fusions (six at L5-S1, three at L4-5, and one at L2-3), and two underwent two-level fusions (one from L-3 to L-5 and the other from L-4 to S-1). The follow-up period ranged from 3 to 12 months (mean 6.8 months).
Conclusions. Although percutaneous lumbar pedicle screw placement has been described previously, longitudinal connector (rod or plate) insertion has been more problematic. The device used in this study allows for straightforward placement of lumbar pedicle screws and rods through percutaneous stab wounds. Paraspinous tissue trauma is minimized without compromising the quality of spinal fixation. Preliminary experience with this device has been promising.

Introduction


The use of pedicle screws for spinal stabilization has become increasingly popular worldwide. Pedicle screw systems engage all three columns of the spine and can resist motion in all planes. Several studies suggest that pedicle screw fixation is a safe and effective treatment for many spinal disorders. Standard techniques for pedicle screw placement, however, require extensive tissue dissection to expose entry points and to provide for lateral-to-medial orientation for optimal screw trajectory. Open pedicle fixation and spinal fusion have been associated with extensive blood loss, lengthy hospital stays, and significant cost.

The purpose of this paper is to describe a technique and instrumentation designed by the senior author (K.T.F.) for minimally invasive posterior fixation of the lumbar spine by using percutaneous screws and rods (Sextant; Medtronic Sofamor Danek, Memphis, TN). Our initial clinical experience will also be included. Although percutaneous lumbar pedicle screw insertion has been previously reported, a minimally invasive approach to inserting a longitudinal connector for these screws has proven more challenging. The Sextant system allows for the straight-forward placement of lumbar pedicle screws and rods through percutaneous stab wounds. The screws and rods are placed in an anatomical position similar to that achieved by an analogous open surgical approach. Paraspinous tissue trauma is greatly minimized without sacrificing the quality of the spinal fixation. Our preliminary experience with this technique has been promising.

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