Biomechanical comparison of traditional and minimally invasive intradural tumor exposures using finite element analysis

Background: Minimally invasive approaches to intradural pathology have evolved in part in an effort to reduce approach related destabilization of the spine. No biomechanical data exist however evaluating the effects of traditional and minimally invasive exposures. Methods: A finite element model of the lumbar spine was generated, and a simulated open laminectomy and a modified hemilaminectomy at L4 were performed. Forces were applied to assess changes in flexion, extension, axial rotation, and lateral bending. Findings: Open laminectomy produced much greater changes in extension, flexion, and axial rotation than the modified hemilaminectomy from the intact. Lateral bending was similarly unaffected for both exposures. Interpretation: The results suggest that a minimally invasive hemilaminar exposure preserves the structural integrity of the lumbar spine and minimizes alterations to segmental motion postoperatively. (C) 2008 Elsevier Ltd. All rights reserved.