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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Multicenter Study Clinical Trial
The dynamic neutralization system for the spine: a multi-center study of a novel non-fusion system.
Various forms of lumbar instability require a surgical stabilization. As an alternative to fusion, a mobile, dynamic stabilization restricting segmental motion would be advantageous in various indications, allowing greater physiological function and reducing the inherent disadvantages of rigid instrumentation and fusion. The dynamic neutralization system for the spine (Dynesys) is a pedicle screw system for mobile stabilization, consisting of titanium alloy screws connected by an elastic synthetic compound, controlling motion in any plane (non-fusion system). ⋯ Long-term screw fixation is dependent on correct screw dimension and proper screw positioning. The natural course of polysegmental disease in some cases necessitates further surgery as the disease progresses. Dynamic neutralization proved to be a safe and effective alternative in the treatment of unstable lumbar conditions.
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Quantification of thermal thresholds is a useful method to assess and follow up the function of afferent small A-delta and C-fibres in patients with nerve dysfunctions. The object of this study was to estimate thermal test-retest repeatability in 19 patients with unilateral sciatica (14 L5 and 5 S1) in affected and non-affected dermatomes on the symptomatic (S) and non-symptomatic (NS) sides. Detection thresholds were measured at six sites, two within each of the L4, L5 and S1 dermatomes. ⋯ The sensitivity was better on the foot than the lateral calf (5 of 14 vs 1 of 14 abnormal thresholds) in the subgroup with L5 sciatica. We conclude that dermatomal thermotesting has acceptable repeatability, particularly at proximal lower extremity sites. The test may be useful in longitudinal investigations of patients with sciatica, e.g. in treatment follow-up studies.
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The release of inflammatory cytokines caused by a disrupted disc may play a critical role in pain production at nerve endings, axons, and nerve cell bodies. Herniated disc tissue has been shown to release inflammatory cytokines such as interleukin-1 beta (IL-1beta), interleukin-6 (IL-6), tumor necrosis factor (TNF), and other algesic chemicals. This study was designed to characterize the effects of these proinflammatory cytokines on the somatosensory neural response at the dorsal root level in rats. ⋯ IL-1beta, IL-6, and TNF may be neurotoxic to dorsal root axons. Furthermore IL-1beta and TNF may sensitize the peripheral receptive fields. This study suggests that dorsal roots may be impaired by these proinflammatory cytokines.
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Using a non-human primate model, the current study was undertaken to investigate the efficacy of the AcroFlex lumbar disc as an intervertebral disc prosthesis, based on biomechanical, histopathologic and histomorphometric analyses. A total of 20 mature male baboons (Papio cynocephalus, mean weight 30 kg) were randomized into two equal groups based on post-operative time periods of 6 (n=10) and 12 months (n=10). Each animal underwent an anterior transperitoneal surgical approach to the lumbar spine, with intervertebral reconstructions performed at L3-L4 and L5-L6 using the following techniques: (1) tricortical iliac autograft and (2) AcroFlex lumbar disc. ⋯ This effect may be secondary to the limited surface area of device-vertebral endplate contact. Histomorphometric analysis of porous ingrowth coverage at the vertebral bone-metal interface was more favorable for total disc arthroplasty compared to historical reports of cementless femoral components. This project serves as the first comprehensive in vivo investigation into the AcroFlex disc prosthesis, and establishes an excellent research model in the evaluation of total disc replacement arthroplasty.