Novel pedicle screw and plate system provides superior stability in unilateral fixation for minimally invasive transforaminal lumbar interbody fusion: an in vitro biomechanical study

Jie Li; Hong Xiao; Qingan Zhu; Yue Zhou; Changqing Li; Huan Liu; Zhiping Huang; Jin Shang

doi:10.1371/journal.pone.0123134

Novel pedicle screw and plate system provides superior stability in unilateral fixation for minimally invasive transforaminal lumbar interbody fusion: an in vitro biomechanical study

PLoS One. 2015 Mar 25;10(3):e0123134. doi: 10.1371/journal.pone.0123134. eCollection 2015.

Authors

Jie Li¹, Hong Xiao¹, Qingan Zhu², Yue Zhou¹, Changqing Li¹, Huan Liu¹, Zhiping Huang², Jin Shang¹

Affiliations

¹ Department of Orthopedics, Xinqiao Hospital, The Third Military Medical University, Chongqing, China.
² Department of Orthopaedic and Spinal Surgery, Nanfang Hospital Southern Medical University, Guangzhou, Guangdong, China.

Abstract

Purpose: This study aims to compare the biomechanical properties of the novel pedicle screw and plate system with the traditional rod system in asymmetrical posterior stabilization for minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). We compared the immediate stabilizing effects of fusion segment and the strain distribution on the vertebral body.

Methods: Seven fresh calf lumbar spines (L3-L6) were tested. Flexion/extension, lateral bending, and axial rotation were induced by pure moments of ± 5.0 Nm and the range of motion (ROM) was recorded. Strain gauges were instrumented at L4 and L5 vertebral body to record the strain distribution under flexion and lateral bending (LB). After intact kinematic analysis, a right sided TLIF was performed at L4-L5. Then each specimen was tested for the following constructs: unilateral pedicle screw and rod (UR); unilateral pedicle screw and plate (UP); UR and transfacet pedicle screw (TFS); UP and TFS; UP and UR.

Results: All instrumented constructs significantly reduced ROM in all motion compared with the intact specimen, except the UR construct in axial rotation. Unilateral fixation (UR or UP) reduced ROM less compared with the bilateral fixation (UP/UR+TFS, UP+UR). The plate system resulted in more reduction in ROM compared with the rod system, especially in axial rotation. UP construct provided more stability in axial rotation compared with UR construct. The strain distribution on the left and right side of L4 vertebral body was significantly different from UR and UR+TFS construct under flexion motion. The strain distribution on L4 vertebral body was significantly influenced by different fixation constructs.

Conclusions: The novel plate could provide sufficient segmental stability in axial rotation. The UR construct exhibits weak stability and asymmetrical strain distribution in fusion segment, while the UP construct is a good alternative choice for unilateral posterior fixation of MI-TLIF.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Biomechanical Phenomena
Bone Plates
Cattle
Lumbar Vertebrae / surgery*
Minimally Invasive Surgical Procedures
Pedicle Screws
Range of Motion, Articular
Rotation
Spinal Fusion / instrumentation
Spinal Fusion / methods*

Grants and funding

This work was supported by fund of the Chinese National Science and Technology Support Program (2012BAI14B00) and the Major Project of Chongqing Municipal Science and Technology Commission (cstc2012gg-yyjsB10012). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.