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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Segmental instability represents one of several different factors that may cause or contribute to the failed back surgery syndrome after lumbar microdiscectomy. As segmental lumbar instability poses diagnostic problems by lack of clear radiological and clinical criteria, only little is known about the occurrence of this phenomenon following primary microdiscectomy. Retrospectively, the records of 2,353 patients were reviewed according to postoperative symptomatic segmental single-level instability after lumbar microdiscectomy between 1989 and 1997. ⋯ It can therefore be concluded that (1) patients in their 40s are prone to postoperative narrowing of the intervertebral disc space and hence subsequent intervertebral instability and (2) that a small extent of intervertebral disc resection and preservation of the "segmental frame" may be beneficial in those patients. The present study demonstrated for the first time that the degree of extensive operative techniques in microdiscectomy increased the risk of subsequent segmental instability. In addition, narrowing of the intervertebral space of more than 30% represents a clear radiological sign of segmental instability.
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A model of sacroiliac joint (SIJ) function postulates that SIJ shear is prevented by friction, dynamically influenced by muscle force and ligament tension. Thus, SIJ stability can be accommodated to specific loading situations. The purpose of this study was to examine, in vivo, whether muscles contribute to force closure of the SIJ. ⋯ The finding that SIJ stiffness increased even with slight muscle activity supports the notion that effectiveness of load transfer from spine to legs is improved when muscle forces actively compress the SIJ, preventing shear. When joints are manually tested, the influence of muscle activation patterns must be considered, since both inter- and intra-tester reliability of the test can be affected by muscle activity. In this respect, the relation between emotional states, muscle activity and joint stiffness deserves further exploration.
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The author presents a retrospective clinical study addressing the outcome after posterior stabilisation of the occipital-cervical spine using a new cranio-spinal implant. The range of surgical methods for operative treatment of occipito-cervical instability remains wide, and it is still a demanding technique that frequently requires improvisation by the surgeon. No previous studies have been published of occipito-cervical reconstructions using two contoured asymmetrical occipital plates interdigitating in the midline at the occiput and allowing various methods of cervical fixation, by means of different hooks, a claw device or screws. ⋯ No serious complications occurred. One occipital screw broke and one hook loosened, needing a re-fixation. The simplicity of applying these cranio-cervical implants makes them practical for every orthopaedic or neurosurgeon with a special interest in cervical spine surgery.
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Randomized Controlled Trial Comparative Study Clinical Trial
Prediction of fusion and importance of radiological variables for the outcome of anterior cervical decompression and fusion.
In a prospective randomised study with a 2-year follow-up, 103 patients were randomised to anterior cervical decompression and fusion (ACDF) with a cervical carbon-fibre intervertebral fusion cage (CIFC) or the Cloward procedure (CP). The purpose of the present study was to report predictors for fusion and also to investigate the importance of radiological variables for the clinical outcome. Gender, age, smoking habits, disc height, segmental kyphosis and type of surgical procedure were used as independent (before surgery) variables in a multiple regression model. ⋯ One can conclude that male gender and type of surgery were significant predictors for a healed fusion and that pseudarthrosis affected outcome. In contrast to the commonly held view based mainly on theoretical considerations, no effect on clinical outcome could be demonstrated for segmental kyphosis and disc height at follow-up. Overall, the study shows that the importance of radiological factors as predictors for fusion as well as clinical outcome is limited.
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The purpose of the study was to investigate possible variation of thickness of the cervical spine endplate with respect to endplate orientation (superior or inferior endplate) and level distribution (C4-C7). Six human cervical spine segments C4-C7 were used to create six specimen of C4, C5, C6, and C7, respectively. The bony endplates of each vertebra were cleaned carefully from disc tissue without damaging the endplates. ⋯ In both superior and inferior endplates, peripheral areas were thicker than the central region (Scheffe-test, P<0.001). For all levels, the endplate within the peripheral regions was thicker than within the central region and the difference reached significance for the superior and inferior endplate of C4, C5, and C6 and the inferior endplate of C7 (Scheffe-test, P<0.05). The peripheral regions of the cervical spine endplate are usually thicker than its central region, regardless of endplate orientation and level (C4, C5, C6, C7) distribution.