• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.2
• /
• pp.130-136
• /
• 2010

For stability analysis of the lumbar spine, the hypothesis presented is that the disc has stress sensors driving feedback mechanism, which could react to the imposed loads by adjusting the contraction of the muscles. Fusion in the motion segment of the lumbar spinal column is believed to alter the stability of the spinal column. To identify this effect finite element (FE) models combined with optimization technique was applied and quantify the role of each muscle and reaction forces in the spinal column with respect to the fusion level. The musculoskeletal FE model was consisted with detailed whole lumbar spine, pelvis, sacrum, coccyx and simplified trunk model. Vertebral body and pelvis were modeled as a rigid body and the rib cage was constructed with rigid truss element for the computational efficiency. Spinal fusion model was applied to L3-L4, L4-L5, L5-S1 (single level) and L3-L5 (two levels) segments. Muscle architecture with 46 local muscles was used as acting directions. Minimization of the nucleus pressure deviation and annulus fiber average axial stress deviation was selected for cost function. As a result, spinal fusion produced reaction changes at each motion segment as well as contribution of each muscle. Longissimus thoracis and psoas major muscle showed dramatic changes for the cases of L5-S1 and L3-L5 level fusion. Muscle force change at each muscle also generated relatively high nucleus pressure not only at the adjacent level but at another level, which can explain disc degeneration pattern observed in clinical study.

• Journal of Digital Convergence
• /
• v.11 no.11
• /
• pp.613-620
• /
• 2013

This study was conducted to measure and analyze the changes in paraspinal muscles of acute and chronic low back pain patients using MRI, and to provide clinical basic data for diagnosis and treatment for low back pain. For this purpose, 20 patients with acute low back pain frome August 2012 to January 2013 which occurred within 12 weeks, and 20 patients with chronic low back pain that progressed over 12 weeks, were chosen as subjects, and their MRI measurements were compared with one another. As a result, in relation to in the fatty degeneration ratio of the left spine and right spine, there were significant differences in erector spinae and multifidus(p<.001), and in relation to the Fat Infiltration ratio between all the groups, there were significant differences in psoas major, erector spinae and multifidus between the acute low back pain patient group and the chronic low back pain patient group(p<.001). In the post-hoc test, multifidus and erector spinae in the acute low back pain group and chronic low back pain group showed the highest Fat Infiltration ratio. The serious Fat Infiltration of multifidus and erector spinae in the chronic low back pain group led to weakened strength of muscles that stabilize the spine. In conclusion, it is considered that this study would present important data and basis in making acute and chronic low back pain patients pay more attention to multifidus and psoas major during rehabilitation exercise, and selecting a rehabilitation exercise program.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.1
• /
• pp.115-122
• /
• 2011

Recently, we have proposed a hypothesis that spinal structures have a stress sensor driving feedback mechanism, In the human spine, spinal structure could react to modify muscular action in such a way so as to equalize stress at the disc, therefore reduce the risk of injury, In this analysis, abdominal muscle and abdominal pressure, which were not included in the previous study, were added to identify those effects in spine stability during upright stance posture for the case where the intervertebral disc plays the role of mechanoreceptor, The musculoskeletal FE model was consisted with detailed whole lumbar spine, pelvis, sacrum, coccyx and simplified trunk model. Muscle architecture with 46 local muscles containing paraspinal muscle and 6 rectus abdominal muscles were assigned according to the acting directions. The magnitude of 4kPa was considered for abdominal pressure. Minimization of the nucleus pressure deviation and annulus fiber average tension stress deviation was chosen for cost function. Developed model provide nice coincidence with in-vivo measurement (nucleus pressure). Analysis was conducted according to existence of co-activation of abdominal muscle and abdominal pressure. Antagonistic activity of abdominal muscle produced stability of spinal column with relatively small amount of total muscle force. In contrast to the abdominal muscle, effect of abdominal pressure was not clear that was partly depending on the assumption of constant abdominal pressure.