Logo image
Interpedicular Travel in the Evaluation of Spinal Implants An Application in Posterior Dynamic Stabilization
Journal article

Interpedicular Travel in the Evaluation of Spinal Implants An Application in Posterior Dynamic Stabilization

Daniel J. Cook, Matthew S. Yeager and Boyle C. Cheng
Spine (Philadelphia, Pa. 1976), v 37(11), pp 923-931
15 May 2012
PMID: 22024893

Abstract

Clinical Neurology Life Sciences & Biomedicine Neurosciences & Neurology Orthopedics Science & Technology
Study Design. In vitro flexibility testing of the lumbar spine. Objective. The goal of this study was to evaluate a motion-preserving posterior dynamic stabilization (PDS) implant based on newly defined parameters describing interpedicular kinematics. Summary of Background Data. PDS implants have been designed as either motion-preserving or adjunct-to-fusion devices to treat various degenerative spinal pathologies. The ambiguity of design and evaluation goals and the inability of traditional biomechanical parameters to appropriately describe the behavior of PDS devices in vitro have served as the impetus to develop kinematic parameters more specific to this class of device. Methods. Flexibility testing of 6 fresh-frozen human lumbar spines was conducted before and after destabilization of the index level (L4-L5). Testing under the same protocol was repeated after treatment at the index level with a 1-level PDS device, extension of the device to the adjacent inferior level (L5-S1), and treatment with a hybrid construct consisting of the PDS implant at L4-L5 and rigid fixation at L5-S1. The kinematic response was recorded using an optoelectric tracking system and reported in terms of intervertebral range of motion (ROM) and newly developed parameters describing interpedicular motion. Results. Based on ROM and interpedicular kinematics, the devices implanted at L4-L5 provide significant but not differing stabilization in flexion-extension with implantation after a significant destabilization procedure. Interpedicular kinematic results indicate that the 2-level construct contributes to significantly more motion at L5-S1 compared with rigid fixation. This result was not detected when evaluated by the ROM metric. Conclusion. Those involved in the design and evaluation of PDS devices may benefit from evaluation of interpedicular kinematics. Evaluating intervertebral motion from the perspective of the pedicle screw allows for a direct and intuitive translation between in vitro test results and design parameters. Furthermore, these parameters may provide additional clinical insight into the biomechanics of the healthy and pathological spine. The study presented indicates that this approach may be more sensitive in detecting differences in implant motion between PDS devices.

Metrics

6 Record Views
17 citations in Scopus

Details

UN Sustainable Development Goals (SDGs)

This publication has contributed to the advancement of the following goals:

#3 Good Health and Well-Being

InCites Highlights

Data related to this publication, from InCites Benchmarking & Analytics tool:

Collaboration types
Domestic collaboration
Web of Science research areas
Clinical Neurology
Orthopedics
Logo image