Retrospective Analysis and Modifications of Retractor Systems for Anterior Odontoid Screw Fixation

Stan G. Shalayev, M.D.; In Ki Mun, Ph.D.; Gregory S. Mallek; Sylvain Palmer, M.D.; Allan D. Levi, M.D., Ph.D.; Todd M. Lasner, M.D.; Allen B. Kantrowitz, M.D.

Disclosures

Neurosurg Focus. 2004;16(1) 

In This Article

Abstract and Introduction

The authors present an in-depth retrospective analysis of retractor systems for anterior odontoid screw fixation. They discuss various modifications and innovations of such systems and describe their own tubular retractor system, in which a beveled end conformal to the ventral surface of the vertebral column at the C2–3 level is introduced together with an incorporated light source. This new retractor system allows optimal anatomical exposure for controlled odontoid screw placement with improved protection of surrounding vital structures.

Anterior screw fixation of the dens has entered the surgical armamentarium for the management of odontoid fractures, a subject of surgical controversy.[2,6,7,11–13] Compared with other therapeutic options that are available, including external halo fixation and posterior cervical fusion, anterior screw fixation of the dens can potentially lower the morbidity rate in patients.[4,8,14,15,17] Anterior screw fixation of the dens was initially described independently by Nakashimi and Boehler in the early 1980s. Extensive series of long-term studies undertaken by Aebi and colleagues[1] and by Apfelbaum, et al.,[3] demonstrated an excellent clinical feasibility of the approach by providing documentation of a fusion rate of 88% in acute cases and 25% in chronic cases of nonunion of the dens. A retrospective analysis of approaches for odontoid fracture fixation revealed that a rigid-tunnel type of construct is the most beneficial solution for this intervention as long as soft tissues in the high cervical segments are protected while the instrumentation is being placed. Toward that end, Apfelbaum introduced a modification of a conventional anterior cervical retractor. In his design, the conventional transverse anterior cervical retractor is augmented by a detachable third blade that is capable of supporting the posterior wall of the pharynx. A toothed tube is subsequently driven into the ventral surface of C-3 to protect local tissues further from the rotating surgical tools.

Hott, et al.,[9] have recently described the use of the METRx retractor[5,10] (Medtronic Sofamor Danek, Memphis, TN) as a retractor system for this surgery, to avoid mobilization of the longus colli muscle by stabilizing the retractor with a bedside rail.

In this paper we present a further modification of the METRx system, in which the tubular retractor has been optimized to permit visualization and retraction along the anticipated trajectory that is required for placement of the odontoid screw. A light source has also been incorporated in the new design.

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