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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For several years, digitized small radiographs are used to measure Cobb angle in idiopathic scoliosis. The interobserver and intraobserver Cobb angle measurement variability associated with small radiographs were compared with measurement variability associated with the long-cassette radiographs. Twenty adolescent patients with a double major idiopathic scoliosis had erect full-spine p-A radiographs and Cobb angle measurements performed by eight different observers on a 30 x 90 cm plain-film radiograph and a digitized 14 x 42 cm image. ⋯ In our study, Cobb angle determination was not found to vary significantly with film size. The small film image used for full-spine radiographs in our institution allows manual Cobb angle measurements to be performed. A study is currently conducted in our institution to determine if a computer-assisted measurement method significantly improves Cobb angle measurements reliability in routine practice compared with manual measurements of Cobb angles on small films.
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The objective of this study is to determine the intraobserver and interobserver reliability of end vertebra definition and Cobb angle measurement using printed and digital radiographs of 48 patients with scoliosis. The Cobb angle and the end vertebra were assessed by six observers in 48 patients with scoliosis using printed and digital radiographs. Definition of end vertebra and measurement of the Cobb angle was repeated three times with a 3 week interval. ⋯ Until we develop a proper tri-dimensional measuring system an error is introduced. For the Cobb angle measurement the definition of end vertebrae introduces the main source of error. Digital radiography does not improve the measurement accuracy.
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Extensive anatomical differences suggest that cervical and lumbar discs may have functional differences also. We investigated human cervical discs using "stress profilometry". Forty-six cadaveric cervical motion segments aged 48-90 years were subjected to a compressive load of 200 N for 20 s, while compressive 'stress' was recorded along the posterior-anterior midline of the disc using a pressure transducer, side-mounted in a 0.9 mm diameter needle. ⋯ Central regions of many cervical discs show the characteristics of a "tethered fluid" which can equalise stress over small distances, but not large. This may be attributable to their fibrous texture. The small radial diameter of the cervical posterior annulus may facilitate buckling and thereby prevent it from sustaining high compressive stresses.
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Several studies have suggested that the pelvis is involved in the etiology or pathogenesis of adolescent idiopathic scoliosis (AIS). The purpose of this retrospective, cross-sectional radiographic study is to identify any correlation between the transverse plane rotational position of the pelvis in stance and operative-size idiopathic or congenital scoliosis deformities, using Scheuermann's kyphosis and isthmic spondylolisthesis patients for comparison. The hypothesis tested was that the direction of transverse pelvic rotation is the same as that for a thoracic scoliosis. ⋯ All congenital scoliosis patients studied had main thoracic curves and significant transverse plane pelvic rotation in the same direction as the thoracic curve. There was no transverse plane pelvic rotation in the Scheuermann's kyphosis or isthmic spondylolisthesis patients. We interpret these findings as consistent with a compensatory rotation of the pelvis in the same direction as the main thoracic curve in most patients with a compensatory thoracolumbar/lumbar curve as well as in patients with main thoracic congenital scoliosis.