A Biomechanical Analysis of Zielke, Kaneda, and Cotrel-Dubousset Instrumentations in Thoracolumbar Scoliosis A Calf Spine Model

Abstract

A biomechanical study was performed in order to evaluate the initial stability of three spinal instrumentation systems, applied to a scoliosis model. Five calf spines (T11-L2) were destabilized anteriorly, and, by inserting a wedge-shaped resin disc within each destabilized intervertebral space, a thoracolumbar scoliosis was created. Three spinal instrumentation systems (Zielke anterior instrumentation, Kaneda anterior multisegmental fixation device, and Cotrel-Dubousset posterior instrumentation) were applied to correct the simulated scoliotic condition. Mechanical nondestructive cyclical testing in axial compression, rotation, flexion, and extension was performed on each spinal construct. The Kaneda device was the most stable instrumentation in all four loading conditions. Zielke instrumentation failed to restore the stability to the level of the intact spine in rotation, and was the least rigid instrumentation in flexion and extension. The Cotrel-Dubousset instrumentation demonstrated favorable stability in flexion and extension, but became the least rigid instrumentation in axial compression and rotation. This study suggests that a one-stage procedure with Zielke instrumentation and a two-stage procedure (anterior release with bone graft and posterior stabilization) with Cotrel-Dubousset instrumentation applied for the correction of scoliosis, should be supplemented with additional external or internal supports. The Kaneda device may offer enough stability with an anterior procedure alone in the correction of scoliosis.