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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To analyze the disc hydration and volumetric changes of the intervertebral disc after scoliosis surgery depending on the sagittal spino-pelvic organization. ⋯ This prospective MRI study showed a significant and sustainable improvement in T2 hypersignal of the disc, indirectly indicating improvement of disc hydration content after AIS surgery. Analysis of disc volumetric changes according to the pelvic incidence suggests that these changes are under the influence of the sagittal spino-pelvic alignment. PI seems to play a key role in the homeostasis of the discs under fusion and should be taken into account for preoperative planning. The restoration of the lumbo-pelvic congruence may help to limit early degenerative changes in the free-motion segment discs after AIS surgery. Hydration content was less sensitive to surgery when PI was high, suggesting higher shear stress in the lower discs. Longer follow-up is required to confirm this hypothesis.
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Adolescent idiopathic scoliosis occurs far more often in girls than in boys, and its initiation and progression normally takes place around the adolescent growth spurt. Despite extensive research into the topic, no solid explanation for both well-known phenomena has been offered. The sagittal profile of the growing spine has been demonstrated previously to play an important role in the spine's rotational stiffness. Changes in this sagittal alignment around the growth spurt can be inferred to play an important role in the spine's propensity to develop a rotatory deformity, i.e. scoliosis. The aim of this study was to quantify sagittal spino-pelvic alignment and orientation in space of each individual vertebra in normal boys and girls in the beginning, at the peak and at the end of pubertal growth. ⋯ These results imply that the spines of girls during the growth spurt are more posteriorly inclined, and thus rotationally less stable, compared to boys at the same stage of development, as well as compared to girls after the growth spurt. This may explain why initiation and progression of adolescent idiopathic scoliosis are more prevalent in girls around puberty.
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Comparative Study
Pelvic incidence and pelvic tilt measurements using femoral heads or acetabular domes to identify centers of the hips: comparison of two methods.
The aim of the study was to compare pelvic incidence (PI) and pelvic tilt (PT) measurements using the bicoxofemoral axis obtained from either femoral heads or acetabular domes on lateral digital radiographs of the spine. ⋯ We suggest that either the femoral heads or the acetabular domes may be used for reliable PI and PT measurements on the lateral standing long-cassette digital radiographs of the spine.
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Pelvic tilt is usually measured on a full spine sagittal view. The sacral-femoral-pubic angle (SFP) has been previously described as a reproducible method to estimate pelvic tilt on a pelvis AP view. The aim of our study is to determine the reliability of the extrapolated pelvic tilt (ePT) using the SFP angle in the pediatric population. ⋯ IV.
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The alignment of the cervical spine is of primary importance to maintain horizontal gaze and contributes to the functional outcome of patients. Cervical spine alignment after correction of major sagittal imbalance has rarely been reported in the literature. ⋯ LL restoration decreased the need of compensation at the pelvis and thoracic spine. The distal CL and C7 slope decreased because there was no need for compensation at this level after the surgery, but the proximal cervical spine takes a slightly flexed position to maintain horizontal sight. EAM tilt measures the head position toward C7, and is close to 0° even in severe cases. Changes of this parameter after surgery are insignificant, probably due to the balance between upper and lower cervical segments; when one of these segments shifts backward the other shifts forward and the result is a balanced head over C7.