Biomechanical analysis of Graf's dynamic spine stabilisation system ex vivo

The most frequent causes of chronic lumbar spine instability are of degenerative or traumatic origin. Numerous anterior and posterior stabilisation devices were developed for anatomical reconstruction of the spinal alignment and fusion of the spine to restore stability. Fusion of the spine results in increased load of adjacent segments with an increased risk of secondary degeneration which might result in instability or stenosis. To avoid the disadvantages of static devices, Graf developed a method of dynamic surgical treatment of spinal column instabilities, which is based on the principle of flexible stabilisation. This study is analysing the kinematics of discoligamentary intact motion segments compared with the experimentally destabilised human lumbar spine and the influence of Graf's stabilisation. According to our results, rotational instabilities cannot be satisfactorily stabilised by Graf's ligamentoplasty. With the present ex vivo study, it could be shown that it is possible to restore stability after discoligamentary lesion and after facetectomy using Graf's dynamic lordosis ligamentoplasty.