Changes in Intradiscal Pressures due to More Compliant Spinal Stabilization System
Dynamic stabilization of the lumbar spine has gained increasingly popularity. These nonfusion systems are alleged to maintain or restore the intradiscal pressure to magnitudes of the intact spine and have little negative effect on the adjacent segments to the stabilized one. Compliant Nitinol alloy (Ni-Ti) has been used in the manufacture of the rods of the dynamic stabilization systems. In this study, we investigated a dynamic stabilization system with its coiled rods made of Nitinol alloy. Four porcine lumbar spines (T12-L6) were prepared: intact, fixed by a conventional rigid fixation system, fixed by a dynamic stabilization system with 2-coiled rods, fixed by a dynamic stabilization system with 3-coiled rods. Intradiscal pressures were measured at all levels before and after insertion of the implant. Our results show that the rigid stabilization system resulted in great changes of disc pressure in flexion and extension regardless of spinal levels. However, Intradiscal pressures (IDPs) remained relatively unchanged in models fixed by the dynamic stabilization systems. Changes in intradiscal pressure can lead to altered metabolism within the disc, with potential long-term disc degeneration. These results suggest that the dynamic stabilization systems are superior over traditional fusion implants in maintaining the intradiscal pressure to the intact level at surgical level and adjacent level and can therefore be considered as an alternative method to fusion surgery in these indications while the intradical pressure is preserved.
Young-Ha Kim, Chong-Su Cho, Inn-Kyu Kang, Suk Young Kim and Oh Hyeong Kwon
Y.H. Ahn et al., "Changes in Intradiscal Pressures due to More Compliant Spinal Stabilization System", Key Engineering Materials, Vols. 342-343, pp. 913-916, 2007