European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society
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Comparative Study
Nucleus pulposus inhibits the axonal outgrowth of cultured dorsal root ganglion cells.
Although it is well established that nucleus pulposus cells may induce structural and functional changes in adjacent nerve roots when placed epidurally, it is not known whether this is due to direct neurotoxic effects or whether the nerve roots are affected indirectly by reduction of nutrition and inflammatory/immunologic mechanisms. In the present study we assessed the effects of various tissues on cultured dorsal root ganglions from newborn rats. ⋯ The study thus showed that there are direct axonotoxic effects induced by the nucleus pulposus, and since frozen nucleus pulposus did not have any effects, it may be assumed that the mechanisms are related to substances produced by the nucleus pulposus cells. The presented model allows for future studies on the neurotoxic properties of nucleus pulposus cell-derived candidate substances.
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Comparative Study
Early histologic changes in lower lumbar discs and facet joints and their correlation.
Biomechanical and histologic studies have highlighted the close functional relationship between lumbar discs and their associated facet joints, and it is conceivable that their degenerative changes are interdependent. However, separation of cause from effect remains controversial. Hitherto, no study in humans has correlated the changes histologically. ⋯ There was no correlation between changes in discs and the associated facet joints at either level. The results of the study showed that microscopic changes are seen in the disc and facet joints from an early age and can be quite marked in some individuals before the age of 40 years. A correlation of degenerative changes within the FSU could not be established.
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Transarticular C1/2 screws are widely used in posterior cervical spine instrumentation. The use of pedicle screws in the cervical spine remains uncommon. Due to superior biomechanical stability compared to lateral mass screws, pedicle screws can be used, especially for patients with poor bone quality or defects in the anterior column. ⋯ Therefore, this technique may be used in a clinical setting, as it offers improved accuracy and reduced radiation dose for the patient and the medical staff. Nevertheless, users should take note of known sources of possible faults causing inaccuracies in order to prevent iatrogenic damage. Small pedicles, with a diameter of less than 4.0 mm, may not be suitable for pedicle screws.
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Both endoscopic lumbar spinal surgery and the non-standardized and unstable retractor systems for the lumbar spine presently on the market have disadvantages and limitations in relation to the minimally invasive surgical concept, which have been gradually recognized in the last few years. In an attempt to resolve some of these issues, we have developed a highly versatile retractor system, which allows access to and surgery at the lumbar, thoracic and even cervical spine. This retractor system - Synframe - is based on a ring concept allowing 360 degrees access to a surgical opening in anterior as well as posterior surgery. ⋯ This ring also functions as a carrier for fiberoptic illumination devices and different sizes of endoscopes, used to transmit the surgical procedure out of the depth of the surgical exposure for both teaching purposes and for the surgical team when it has no longer direct visual access to the procedure. The ring is stable, being fixed onto the operating table, allowing precise minimally open approaches and surgical procedures under direct vision with optimal illumination. This ring system also opens perspectives for an integrated minimally open surgical concept, where the ring may be used as a reference platform in computer-navigated surgery.