Establishment of a goat model of lumbar static and dynamic instability for the research on intervertebral disc degeneration

Abstract:

Objective To establish a practical large animal model of intervertebral disc degeneration（IVDD） for the simulation of the influence of local factors in the human body and the role of pathophysiological stress load on IVDD.Methods In this study，lumbar dynamic and static instability（LDSI） surgery was performed to damage the posterior column structure of the goat spine； the muscles including erector spinae，latissimus dorsi，longissimus lumborum，and spinalis were ligated to destroy the dynamic stability of the lumbar spine，and the spinous process，supraspinous ligament，and interspinous ligament were ligated to destroy the static stability of the lumbar spine，resulting in the imbalance of dynamic and static forces of the lumbar spine and the loss of the stability of the posterior column. With biomechanical stability as the breakthrough point，a goat model of lumbar dynamic and static instability was established without destroying the structural integrity of the intervertebral disc，and during 52 weeks of postoperative follow-up，lumbar spine X-ray，magnetic resonance imaging（MRI），and histopathological changes were used to evaluate disc height index（DHI），Pfirrmann MRI grade，and Masuda histological score.Results In the LDSI group，the DHI of goat lumbar spine was 0.184±0.015 at week 0 before surgery，0.105±0.006 at 26 weeks after surgery，and 0.075±0.007 at 52 weeks after surgery （0 week vs. 26 weeks：P<0.05；26 weeks vs. 52 weeks：P<0.05）. In the LDSI group，the Pfirrmann grade of goat lumbar spine was 1.167±0.408 at week 0 before surgery，2.333±0.516 at 26 weeks after surgery，and 3.667±0.817 at 52 weeks after surgery（0 week vs. 26 weeks：P<0.05；26 weeks vs. 52 weeks：P<0.05）. In the LDSI group，the Masuda histological score of goat lumbar spine was 3.500±0.577 at week 0 before surgery，6.250±0.957 at 26 weeks after surgery，and 8.000±0.816 at 52 weeks after surgery（0 week vs. 26 weeks：P<0.05；26 weeks vs. 52 weeks：P<0.05）.Conclusion LDSI can cause the reduction in the height of the intervertebral disc，the blurring of endplate boundary，and the reduction in water content in goats. It simulates the process of IVDD caused by long-term repeated strain of human body without destroying the structural integrity of the intervertebral disc，which is more in line with the real condition of human body and may provide help for research on the pathogenesis of IVDD.