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World J Clin Cases. Jul 16, 2013; 1(4): 134-139
Published online Jul 16, 2013. doi: 10.12998/wjcc.v1.i4.134
Elastic resistance of the spine: Why does motion preservation surgery almost fail?
Alessandro Landi
Alessandro Landi, Department of Neurology and Psychiatry, Division of Neurosurgery, University of Rome “Sapienza”, 00181 Rome, Italy
Author contributions: Landi A solely contributed to this paper.
Correspondence to: Alessandro Landi, MD, PhD, Department of Neurology and Psychiatry, Division of Neurosurgery, University of Rome Sapienza, Viale del Policlinico 155, 00181 Rome, Italy. dott.alessandro.landi@gmail.com
Telephone: +39-329-0641772 Fax: +39-06-4997911
Received: February 22, 2013
Revised: June 5, 2013
Accepted: June 8, 2013
Published online: July 16, 2013

Single metamere motility should not be interpreted merely as a movement on the 3 planes but also, and above all, as elastic resistance to dynamic stress on these 3 planes. In the light of this consideration, the aim of motion preservation is to neutralize excessive movements while preserving the physiological biomechanical properties of the metamere involved to interrupt the progression of degenerative processes and to prevent adjacent segment disease. Despite the fact that a myriad of devices have been developed with the purpose of achieving dynamic neutralization of the spine, there are now some doubts regarding the true efficacy of these devices.

Keywords: Elastic resistance, Disc prosthesis, Dynamic implant, Interspinous device, Biomechanics

Core tip: Elastic resistance of the spinal motor unit is a biomechanical property often underestimated but crucial for the stability of the spine. The biomechanics of dynamic implants take into account only the motility of the devices and not the elastic resistance. Is it possible that this is the reason why dynamic implants almost fail?