| 1. |
- Henriques, Thomas, et al.
(författare)
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Distractive flexion injuries of the subaxial cervical spine treated with anterior plate alone
- 2004
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Ingår i: Journal of Spinal Disorders & Techniques. - 1536-0652 .- 1539-2465. ; 17:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- The clinical and radiographic effect of anterior plate fixation alone was evaluated in 36 consecutive patients with distractive flexion (DF) injuries in the lower cervical spine. Mean follow-up time was 15 months. The aim of the present study was to determine whether anterior plate fixation alone provides sufficient stability when treating DF injuries in the cervical spine. Solid union was seen in 6 of 6 patients with stage 1 injury and in 15 of 17 patients with stage 2 injury. In the patients with stage 3 injury, 7 of 13 of the anterior fixations failed. These failures occurred mainly among the patients with severe neurologic injuries. We believe these findings substantiate the use of anterior plate alone for DF injuries at stage 1 and 2 but disqualify anterior plate fixation alone for DF injuries at stage 3, with neurologic injury present.
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| 2. |
- Ekström, Lars, 1959, et al.
(författare)
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In vivo porcine intradiscal pressure as a function of external loading
- 2004
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Ingår i: J Spinal Disord Tech. - 1536-0652. ; 17:4, s. 312-6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Spinal loading during daily activity as it relates to the ability of the intervertebral disc to sustain its integrity has been a major issue in spinal research. The purpose of this investigation was to establish the relationship between the intervertebral disc pressure in the nucleus and the load applied to the motion segment in an in vivo porcine model. METHODS: Nine domestic pigs were used in this study. A miniaturized servohydraulic testing machine was affixed to the lumbar spine via four intrapedicular screws, which were inserted bilaterally into the L2 and L3 vertebrae. A pressure needle was inserted through the lateral part of the L2-L3 disc annulus and into the nucleus pulposus. Force, deformation, and intradiscal pressure data were collected during a loading scheme that consisted of applying a set of constant loads in increasing order, that is, 50, 100, 150, 200, and 250 N. Each load was applied for 30 seconds followed by 30-second restitution. RESULTS: Intradiscal nucleus pressure was found to correlate to the applied load in all cases. Linear regression analyses resulted in the following equation: intradiscal pressure (MPa) = 0.08 + 1.25E(-3)(load, N), r(2) = 0.81, n = 8. Intradiscal pressure was also highly linearly dependent on the stress. The intrinsic intradiscal pressure was found to be 81 +/- 5 kPa. The results also indicated that the pressure within the disc exhibited a creep behavior. CONCLUSION: In conclusion, pressure in the nucleus of the porcine intervertebral disc was linearly related to the applied load and stress.
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| 3. |
- Holm, Sten, 1948, et al.
(författare)
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Experimental disc degeneration due to endplate injury
- 2004
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Ingår i: J Spinal Disord Tech. - 1536-0652. ; 17:1, s. 64-71
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to create an experimental model of disc degeneration that closely mimicked human disc degeneration. In six domestic pigs, an L4 cranial endplate perforation into the nucleus pulposus was made. Three months postoperatively, compressive testing was performed on the L2-L4 motion segments, and intradiscal pressure was measured in the intervening discs. Histochemical and morphologic examinations were made on the excised degenerated and adjacent discs. A significant reduction in water content was observed in the outer anterior annulus of the degenerated disc. In the nucleus, the proteoglycan content was significantly reduced, as well as the cellularity, although not significantly. The nucleus lost its gel-like structure and was discolored, and there was delamination of annular layers. Intradiscal pressure in the nucleus was significantly lower in the degenerated disc. In conclusion, experimental degeneration of the intervertebral disc induced by endplate penetration resembled human disc degeneration, as exemplified by biochemical and structural changes.
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| 4. |
- Onda, A., et al.
(författare)
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Lumbar sympathectomy increases blood flow in a dog model of chronic cauda equina compression
- 2004
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Ingår i: J Spinal Disord Tech. - 1536-0652. ; 17:6, s. 522-5
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: This study was designed to assess changes in blood flow of the dog cauda equina after lumbar sympathectomy using an experimental chronic cauda compression model. METHODS: The cauda equina was compressed at 10 mm Hg with a plastic balloon in all animals (n = 12). One week later, bilateral lumbar sympathectomy was carried out in the LSX group (n = 7), and vessels of the cauda equina were thereafter observed for 90 minutes using a specially designed microscope supplied with a video camera. Five animals did not undergo sympathectomy and were used as controls. The volume of blood flow was calculated from two parameters: velocity (mm/s) and diameter (microm) of a vessel observed in each animal. RESULTS: The increment in vessel diameter in the LSX group was pronounced at 30 and 45 minutes after sympathectomy compared with the control group (P < 0.05). Blood flow in the LSX group was increased at 30 minutes depending on dilation of the vessel diameter compared with the control group (P < 0.05). The velocity in the observed vessels remained unchanged throughout the measurements. CONCLUSIONS: These data suggest that lumbar sympathectomy could induce an increase in blood flow of the compressed cauda equina. As lumbar sympathetic block increases blood flow not only in the lower limbs but also in the cauda equina, it might be evaluated for a conservative treatment of intermittent claudication due to lumbar spinal canal stenosis.
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