“Dynamic Fusion” in Degenerative Lumbar Spine Disorders

Abstract

Introduction Dynamic stabilization in lumbar degenerative disorders has become very popular in the last few years. The basic concept of pedicle-screw-based systems is to reduce stiffness of the implants to allow load sharing between instrumentation system and functional spine (movement) unit to prevent adjacent segment syndrome. Basic biomechanical requirements for this philosophy are as follows: (a) a predicable load distribution to the intervertebral disk, (b) the limitation (control) of range of motion, and (c) to maintain and/or to restore the sagittal (sacral) balance. Disk degeneration results in loss of disk height and increase of axial compression loading in the posterior spine elements, probably accompanied with accelerated facet degeneration (arthrosis). Challenged by G. Perrinás reports in the late 1990s we started in 2002 with dynamic (semirigid) transpedicular stabilization systems in degenerative lumbar spine disorders using Isolock device, later using Isobar and AladynR device also. Materials and Methods This paper presents an inhomogene case presentation of 26 patients with different perception of degenerative lumbar disorders. Patients underwent a so called “Dynamic Fusion” between 2003 and 2007 using PLIF or TLIF added by posterior transpedicular dynamic (semirigid) stabilization. The case presentation presents preoperative, postoperative radiographs, and maximally follow-up radiographs to show a perfect bony healing in anterior elements. Definition of Dynamic Fusion Semirigid pedicle screw systems allow an increased anterior column load-sharing leading to favor osteogenesis with enhanced interbody fusion. This physical phenomenon is related to Wolffás Law. Lavaste and Perrin validated in 1993 in a finite element model of the lumbar spine that semirigid posterior instrumentation increases compared to rigid instrumentation of the load transmission through the anterior column. This observation and the publication by Goel et al confirmed that dynamic stabilization systems enable more load through the anterior column and the interbody graft compared to rigid systems without compromising stability, led to changing philosophy. We started to combine PLIF/TLIF with posterior transpedicular semirigid stabilization over the instrumented segment. Results No loosening signs of the PLIF/TLIF implants have been followed-up in this patient cohort. The evaluated pain relief is depended on many factors but all patients had a pain level degree in the VAS (25%). Conclusion The PLIF/TLIF in degenerative lumbar spine disorders showed in combination with posterior semirigid stabilization good clinical and radiographical results. No implant loosening has been followed up. I confirm having declared any potential conflict of interest for all authors listed on this abstract Yes Disclosure of Interest None declared Perrin G: Treatment of lumbar spondylolisthesis and related unstable spinal lesions: the usefulness of PLIF with cages and dynamic interpedicular posterior fixation for circumferential arthrodesis and prevention of adjacent level degeneration. presented at the 3rd World Spine Meeting, Rio de Janeiro, 2005 Goel VK, Lim Th, Gwon J, et al. Effects of rigidity of an internal fixation device. A comprehensive biomechanical investigation. Spine 1991;16:155–161