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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Some patients with scoliosis have a relatively short vertebral canal. This poses the question of whether a short spinal cord may sometimes cause scoliosis. The present paper presents two observations that may support this concept. ⋯ The study confirms that the vertebral canal and the intervertebral foraminae retain their original orientation. The spinal cord is eccentric in the canal towards the concavity of the curve; the major component of rotation occurs anterior to the vertebral canal and the axis of this rotation seems to be at the site of the spinal cord. These observations do not establish that a short spinal cord will result in scoliosis, but the results are compatible with this hypothesis, and that impairment of spinal cord growth factors may sometimes be responsible for scoliosis.
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The aim of the current study is twofold: first, to compare load sharing in compression between an intact and a surgically repaired lumbar spine motion segment L3/4 using a biomechanically validated finite element approach; second, to analyse the influence of bone mineral density on load sharing. Six cadaveric human lumbar spine segments (three segments L2/3 and three segments L4/5) were taken from fresh human cadavers. The intact segments were tested under axial compression of 600 N, first without preload and then following instrumented stabilisation. ⋯ Using 10 MPa--representing soft, osteoporotic bone--this percentage decreased, but it increased using 100 MPa in both the intact and the altered segment. Thus, it is concluded that reconstruction of both the disc and the posterior elements with the implants used in the study recreates the ability of the spine to act as a load-sharing construction in compression. The similarity in load sharing between normal and instrumented spines appears to depend on assumed bone density, and it may also depend on applied load and loading history.
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Whiplash, a common injury following motor vehicle crashes, is associated with high costs and a prognosis that is variable and difficult to predict. We studied the profile of recovery from whiplash and assessed whether presenting signs and symptoms directly after the crash were predictive of whiplash prognosis. We formed a population-based incident cohort of all 2627 individuals who sustained a whiplash injury resulting from a motor vehicle crash in the province of Québec, Canada, in 1987, and followed these patients for up to 7 years. ⋯ In contrast, using a classification of injury severity previously proposed by the Québec Whiplash Associated Disorders Task Force, the median recovery time varied from 17 to only 123 days. We conclude that whiplash patients presenting with several specific musculoskeletal and neurological signs and symptoms will have a longer recovery period. These patients can easily be identified and closely monitored and targeted for the evaluation of early intervention programmes aimed at managing whiplash patients with a poor prognosis.
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Comparative Study
Biomechanical compression tests with a new implant for thoracolumbar vertebral body replacement.
The authors present an investigation into the biomechanical functioning of a new titanium implant for vertebral body replacement (Synex). Possible indications are fractures and/or dislocations with damage of the anterior column, posttraumatic kyphosis and tumors of the thoracolumbar spine. The construction must be supplemented by a stabilizing posterior or anterior implant. ⋯ A significant (P < 0.001) correlation (R = 0.89) between Fmax and BMD was found. Synex was found to be at least comparable to MOSS concerning the compressive performance at the vertebral end-plate. A possible consequence of the significantly higher mean compression forces between 1 and 2 mm displacement might be decreased collapse of the implant into the vertebral body in vivo.
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The present study investigates the diagnostic value of rotatory computed tomography (CT) examinations in normal subjects and patients with whiplash associated disorders (WAD), with the aim of reproducing earlier findings of rotatory CT studies. Forty-seven WAD patients with persistent complaints after a rear-end collision (non-cranial contact acceleration/deceleration trauma) were enrolled in this study. To guarantee a maximally homogeneous study population, only WAD patients with a marked passive cervical retroflexion restriction were included. ⋯ Excessive RR values were only found at C0/C1. A traumatic lesion of the ligaments at C0/C1, which prevent vertical translation of the skull with regard to the atlas, is hypothesised. The results of the discriminant analysis of the RR values make this method applicable for the individual WAD patient in daily practice.