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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Several anterior and posterior methods are today available for stabilization of the cervical spine. Factors such as level and degree of instability, method of decompression, bone quality, length of fixation and safety factors influence the choice of method for a particular patient. The use of laminar hooks in the cervical spine has been restricted by fear of cord compression with the potential of tetraplegia. ⋯ In 95% of the hooks no deformation of the dural sac was observed and there was no evidence of spinal cord deformation. From an anatomical point of view, laminar hook instrumentation can be considered a safe procedure. The study shows, however, that hooks inserted in the cervical spine have a close anatomical relationship with the neuraxis, and at stenotic levels the use of other techniques is therefore recommended.
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High-speed cutters are used in the surgery of the cervical spine. Such high-speed devices can produce an aerosol cloud. As a patient can be a reservoir for pathogens, with aerosol-borne paths of transmission, such an aerosol has to be seen as a potential risk of infection for health care professionals present during the surgery and for patients if micro-organisms are transferred through the medical personnel. ⋯ Such aerosols can be contaminated with pathogens if the patient was infected or colonized. Therefore, sufficient protective measures have to be recommended for everyone present in the operating room during such surgeries. In addition, efficient disinfection of the room and all mobile equipment is necessary after each surgery involving high-speed cutting devices.
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Loosening of the pedicle screws with subsequent non-union or loss of correction is a frequent problem in spinal instrumentation. In a clinical pilot study, coating of pedicle screws with plasma-sprayed hydroxyapatite (HA) resulted in a significant increase of removal torque. An experimental study was performed to investigate the effects of HA coating on the pull-out resistance. ⋯ At 12 weeks, the average stiffness was significantly higher for the HA-coated screws, while there was no significant differences in stiffness between the two screw types at 0 and 6 weeks. Energy to failure was significantly higher for coated screws when compared to the uncoated screws at all three time points. HA coating improves fixation of loaded pedicle screws, with increased pull-out resistance and reduced risk of loosening.
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Stabilizing a lumbar spine with an implant alters the mechanical properties of the bridged region. In order to determine whether this procedure is associated with higher loads in the adjacent segments, seven lumbar cadaver spines were mounted in a spine tester and loaded with pure moments of flexion/extension, left and right lateral bending, and left and right axial rotation. The material studied comprised intact lumbar spines, intact spines with bisegmental internal spinal fixators, and postcorpectomy spines both with a graft and fixators and with fixators alone. ⋯ Highly significant differences in these regions (P<0.01) were far below the interspecimen range. We did not find any case where both intradiscal pressure changes and intersegmental motion showed highly significantly differences in the regions adjacent to the bridged one. Our results suggest that disc degeneration, which is sometimes found at the level directly above and below the fixators, is not caused by mechanical factors.
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There are very few studies with more than 20 years' follow-up of lumbar spine fusions for disc degeneration. Currently, there is a lot of interest in the subject of degenerative changes above the level of fusion; this study is concerned with such changes in the very long term (30 years). Twenty-eight patients showing sound fusion on radiographs following posterior midline spinal fusion performed by a single surgeon between 1968 and 1970 were compared with an age- and gender-matched group of 28 patients who had undergone surgery for degenerative disc disease without fusion during the same period, by the same surgeon and using similar criteria for evaluation (Short Form 36 and Oswestry Disability Index; functional testing using self-paced walk and timed up-and-go; flexion and extension lateral radiographs of the lumbar spine). ⋯ However, there was no statistically significant difference between the two groups in the outcomes measured using validated scales and functional testing. The study emphasises the importance of complete evaluation of these patients using validated outcome measurement instruments against the background of radiographic changes and subjective assessment of back pain. It also shows that radiographic changes do not necessarily mean functional impairment in all patients following lumbar spine fusion for degenerative disc disease.