Spinal rigid instrumentations have been used to fuse and stabilize spinal segments as a surgical treatment for various spinal disorders to date. This technology provides immediate stability after surgery until the natural fusion mass develops. At present, rigid fixation is the current gold standard in surgical treatment of chronic back pain spinal disorders. However, such systems have several drawbacks such as higher mechanical stress on the adjacent segment, leading to long-term degenerative changes and hypermobility that often necessitate additional fusion surgery. Dynamic stabilization systems have been suggested to address adjacent segment degeneration, which is considered to be a fusion-associated phenomenon. Dynamic stabilization systems are designed to preserve segmental stability, to keep the treated segment mobile, and to reduce or eliminate degenerative effects on adjacent segments. This paper aimed to describe the biomechanical aspect of dynamic stabilization systems as an alternative treatment to fusion for certain patients. 1. Introduction Lower back pain is one of the major health problems around the world. One of the leading causes of lower back pain is considered to be degeneration of intervertebral disc. Disc herniation, spondylolisthesis, spondylosis, and spinal stenosis may follow intervertebral disc degeneration. Back pain occurs when posterior disc bulges out and impinges the nerve roots due to herniated disc. Another nerve root impingement may be seen in the condition of spinal stenosis, which is a reduction of the diameter of the spinal canal. The treatment options of lower back pain may vary depending on the severity of the case. They include conservative treatment or surgical techniques. Conservative treatments include exercise, medications, physiotherapy, and rehabilitation. Surgical treatment is considered for the patients when the back pain limits their daily activities and when the condition does not respond to other therapies. Surgical methods include decompression with spinal fusion or nonfusion devices. Spinal fusion supported by rigid instrumentation is widely used in the treatment of various spinal disorders. Since the procedure was first introduced by Albee and Hibbs in 1911, fusion has played an important role in the lumbar spine employed operations. The ideal result in performing fusion is to gain the necessary therapeutic goals with the minimal disruption of normal structure and function of the spinal column [1, 2]. However, usage of the rigid instrumentation results in a considerable amount of morbidity and of
C. A. Niosi, Q. A. Zhu, D. C. Wilson, O. Keynan, D. R. Wilson, and T. R. Oxland, “Biomechanical characterization of the three-dimensional kinematic behaviour of the Dynesys dynamic stabilization system: an in vitro study,” European Spine Journal, vol. 15, no. 6, pp. 913–922, 2006.
G. Dubois, B. De Germay, N. S. Schaerer, and P. Fennema, “Dynamic neutralization: a new concept for restabilization of the spine,” in Lumbar Segmental Instability, M. Szpalski, R. Gunzburg, and M. H. Pope, Eds., pp. 233–240, Lippincott Williams & Wilkins, Philadelphia, Pa, USA, 1999.
A. Rohlmann, N. K. Burra, T. Zander, and G. Bergmann, “Comparison of the effects of bilateral posterior dynamic and rigid fixation devices on the loads in the lumbar spine: a finite element analysis,” European Spine Journal, vol. 16, no. 8, pp. 1223–1231, 2007.
W. Schmoelz, J. F. Huber, T. Nydegger, Dipl-Ing, L. Claes, and H. J. Wilke, “Dynamic stabilization of the lumbar spine and its effects on adjacent segments: an in vitro experiment,” Journal of Spinal Disorders and Techniques, vol. 16, no. 4, pp. 418–423, 2003.
W. Schmoelz, J. F. Huber, T. Nydegger, L. Claes, and H. J. Wilke, “Influence of a dynamic stabilisation system on load bearing of a bridged disc: an in vitro study of intradiscal pressure,” European Spine Journal, vol. 15, no. 8, pp. 1276–1285, 2006.
J. Beastall, E. Karadimas, M. Siddiqui et al., “The dynesys lumbar spinal stabilization system: a preliminary report on positional magnetic resonance imaging findings,” Spine, vol. 32, no. 6, pp. 685–690, 2007.
H. Schmidt, F. Heuer, and H. J. Wilke, “Which axial and bending stiffnesses of posterior implants are required to design a flexible lumbar stabilization system?” Journal of Biomechanics, vol. 42, no. 1, pp. 48–54, 2009.
T. L. Schulte, C. Hurschler, M. Haversath et al., “The effect of dynamic, semi-rigid implants on the range of motion of lumbar motion segments after decompression,” European Spine Journal, vol. 17, no. 8, pp. 1057–1065, 2008.
T. Hashimoto, F. Oha, K. Shigenobu et al., “Mid-term clinical results of Graf stabilization for lumbar degenerative pathologies: a minimum 2-year follow-up,” Spine Journal, vol. 1, no. 4, pp. 283–289, 2001.
M. Stoffel, M. Behr, A. Reinke, C. Stüer, F. Ringel, and B. Meyer, “Pedicle screw-based dynamic stabilization of the thoracolumbar spine with the Cosmic-system: a prospective observation,” Acta Neurochirurgica, vol. 152, no. 5, pp. 835–843, 2010.
Z. A. Smith, S. Armin, D. Raphael, and L. T. Khoo, “A minimally invasive technique for percutaneous lumbar facet augmentation: technical description of a novel device,” Surgical Neurology International, vol. 2, no. 165, 2011.
S. Masala, U. Tarantino, G. Nano et al., “Lumbar spinal stenosis minimally invasive treatment with bilateral transpedicular facet augmentation system,” Cardiovascular and Interventional Radiology, 2012.
C. E. Mandigo, P. Sampath, and M. G. Kaiser, “Posterior dynamic stabilization of the lumbar spine: pedicle based stabilization with the AccuFlex rod system,” Neurosurgical Focus, vol. 22, no. 1, article E9, 2007.
A. Reyes-Sánchez, B. Zárate-Kalfópulos, I. Ramírez-Mora, L. M. Rosales-Olivarez, A. Alpizar-Aguirre, and G. Sánchez-Bringas, “Posterior dynamic stabilization of the lumbar spine with the Accuflex rod system as a stand-alone device: experience in 20 patients with 2-year follow-up,” European Spine Journal, vol. 19, no. 12, pp. 2164–2170, 2010.
B. Y. Cho, J. Murovic, K. W. Park, and J. Park, “Lumbar disc rehydration postimplantation of a posterior dynamic stabilization system: case report,” Journal of Neurosurgery, vol. 13, no. 5, pp. 576–580, 2010.
D. G. Kondrashov, M. Hannibal, K. Y. Hsu, and J. F. Zucherman, “Interspinous process decompression with the X-STOP device for lumbar spinal stenosis: a 4-year follow-up study,” Journal of Spinal Disorders and Techniques, vol. 19, no. 5, pp. 323–327, 2006.
D. P. Lindsey, K. E. Swanson, P. Fuchs, K. Y. Hsu, J. F. Zucherman, and S. A. Yerby, “The effects of an interspinous implant on the kinematics of the instrumented and adjacent levels in the lumbar spine,” Spine, vol. 28, no. 19, pp. 2192–2197, 2003.
M. Siddiqui, E. Karadimas, M. Nicol, F. W. Smith, and D. Wardlaw, “Effects of X-Stop device on sagittal lumbar spine kinematics in spinal stenosis,” Journal of Spinal Disorders and Techniques, vol. 19, no. 5, pp. 328–333, 2006.
A. Richter, C. Schütz, M. Hauck, and H. Halm, “Does an interspinous device (Coflex？) improve the outcome of decompressive surgery in lumbar spinal stenosis? One-year follow up of a prospective case control study of 60 patients,” European Spine Journal, vol. 19, no. 2, pp. 283–289, 2010.