SEDL / STP / STP1431-EB / STP11129S

Spinal Implant Transverse Rod Connectors: A Delicate Balance Between Stability and Fatigue Performance

Serhan, H
Manager of Research and Technology, DePuy AcroMed, Raynham, MA

Slivka, M
Research Engineer, DePuy AcroMed, Raynham, MA

Pages: 6    Published: Jan 2003

Download this paper for $25 PDF (172K)          View License Agreement
Abstract

Transverse rod connectors have been shown to significantly increase the torsional stability of rod-based posterior spinal implant systems, which may improve clinical fusion outcomes. This study was conducted to determine the effect of number and positioning of transverse rod connectors on the torsional stiffness and compression bending fatigue strength of ISOLA spinal corpectomy test constructs. Results from static torsion testing indicated that the addition of one and two transverse rod connectors between the pedicle screws greatly increased the torsional stiffness of the constructs (45% and 63%, respectively). When placed above and below the pedicle screws, the increase was less pronounced. Placement of one or two transverse rod connectors between the pedicle screws decreased the fatigue life of constructs in dynamic compression bending. Placement of two rod connectors above and below the upper and lower pedicle screws, respectively, did not reduce the fatigue performance of the constructs. Therefore, there is a delicate balance between torsional stiffness and fatigue performance of spinal constructs when transverse rod connectors are used.