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
Augmentation of mechanical properties in osteoporotic vertebral bones--a biomechanical investigation of vertebroplasty efficacy with different bone cements.
Recent clinical trials have reported favorable early results for transpedicular vertebral cement reinforcement of osteoporotic vertebral insufficiencies. There is, however, a lack of basic data on the application, safety and biomechanical efficacy of materials such as polymethyl-methacrylate (PMMA) and calciumphospate (CaP) cements. The present study analyzed 33 vertebral pairs from five human cadaver spines. ⋯ The lower the initial BMD, the more pronounced was the augmentation effect. Both PMMA and EBC augmentation reliably and significantly raised the stiffness and maximal tolerable force until failure in osteoporotic vertebral bodies. In non-porotic specimens, no significant increase was achieved.
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Instability of the cervical spine following whiplash trauma has been demonstrated in a number of studies. We hypothesized that, in patients with whiplash-associated disorder, rotation of the head would be accompanied by an earlier onset of neck muscle activity to compensate for intrinsic instability. The aim of the study was to examine the range of motion (RoM) of the cervical spine and the onset and activity of the sternocleidomastoid (SCM) muscles during axial rotation, in healthy control subjects and in patients with chronic whiplash-associated disorder. ⋯ The whiplash patient group showed no evidence of the predicted earlier activation of SCM muscles. Many patients never reached the point in the RoM where SCM muscle activity rises steeply, as it does in the healthy controls (the 'elastic zone'), and their movements remained mostly within the region of low muscle activity (the 'neutral zone'). The whiplash patients appeared either unable or unwilling to drive the cervical spine into this region of high muscle activity, possibly because they were restricted by existing pain or fear of pain.
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A longitudinal study was undertaken to analyse the development of posture and spinal mobility during growth and its relationship to low back pain and sports activities. A total of 90 children were examined at 5-6 years of age and re-examined at 15-16. Sagittal configuration and mobility were measured using Debrunner's kyphometer. ⋯ The results of the study showed that kyphosis and lordosis increased and mobility decreased in the 90 children who were examined both at age 5-6 and 15-16 years. The relationship between kyphosis and lordosis decreased in girls but not in boys. Occasional low back pain was reported by 38% of the children at the age of 15-16 years, but back pain was not related to posture, spinal mobility or physical activity.
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It is commonly believed that slight flexion/extension of the head will reverse the cervical lordosis. The goal of the present study was to determine whether slight head extension could result in a cervical kyphosis changing into a lordosis. Forty consecutive volunteer subjects with a cervical kyphosis and with flexion in their resting head position had a neutral lateral cervical radiograph followed immediately by a lateral cervical view taken in an extended head position to level the bite line. ⋯ Out of 40 subjects, only one subject, who was in the significant head extension group and had only a minor segmental kyphosis, changed from kyphosis to lordosis. The results show that slight extension of the head does not change a reversed cervical curve into a cervical lordosis as measured on lateral cervical radiographs. Only small extension angle changes (mean sum = 4.8 degrees) in the upper cervical segments (C2-C4) occur in head extension of 14 degrees or less.