Biomechanical efficacy of a combined interspinous fusion system with a lumbar interbody fusion cage

• Published in: International journal of precision engineering and manufacturing 2015-05, Vol.16 (5), p.997-1001
• Main Authors: Kim, Yeong-Hyeon, Jung, Tae-Gon, Park, Eun-Young, Kang, Guen-Woo, Kim, Kyung-Ah, Lee, Sung-Jae
• Format: Article
• Language: English
• Subjects: Engineering; Industrial and Production Engineering; Materials Science
• ISSN: 2234-7593; 2005-4602
• DOI: 10.1007/s12541-015-0129-7

An interspinous fusion system (IFS) has been introduced as an alternative to pedicle screw fixation (PSF), commonly used in spinal fusion. In this study, a finite element analysis was performed to assess biomechanical efficacy of the combined IFS with an interbody fusion cage. post-operative models were created to compare the biomechanical efficacy of IFS to that of other fixations including: Type 1, Fusion cage only; Type 2, IFS only; Type 3, PSF only; Type 4, Type 1 plus Type 2; Type 5, Type 1 plus Type 3. All device implantations were simulated at L4-5. At the operated level, Type 4 was shown to have comparable reduction in ROM (range of motion) as Type 5 with both models effectively inducing greater stability compared to other models regardless of loading type. At the adjacent level, Type 4 showed less increase in ROM than Type 5 and was closer to the pre-operative level. In terms of the COR (center of rotation) and load sharing between the anterior and posterior parts of the spine, Type 4 remained closer to that of the intact spine. These results suggest that IFS with a cage may help reduce degeneration at adjacent levels while effectively providing stability at the operated level.