Journal of spinal disorders
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Anatomical and biomechanical data have suggested that pedicle screw fixation at the sacrum is optimum in the anteromedial direction into the S1 vertebral body, yet the possibility of posterior iliac crest interference with this screw pathway has been considered but not defined. This study aimed to determine if the anteromedial direction of screw placement into the vertebral body is possible in all cases at S1 and to assess the limiting effect of the posterior iliac crest. Computed tomography scans of the upper sacrum at the S1 pedicle parallel to the sacral endplate were examined in 100 patients. ⋯ On only three occasions (1.5%) was the ideal screw corridor not possible because of posterior iliac crest overlap. In each case, this occurred only unilaterally and when the widest of the screw corridors (12.5 mm) was used. Both the distance between the posterior iliac crests and the space available for optimum screw placement are greater in females than males.
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Combinations of varying degrees of spondylosis and/or ossification of the posterior longitudinal ligament (OPLL), and ossification of the yellow ligament (OYL) contribute to thoracic and lumbar neural compression in North Americans. Preoperative magnetic resonance and computed tomography examinations dictated the surgical approaches used to address spondylosis/OPLL in 11 patients, OYL in 12 patients, and spondylosis/OPLL and OYL in 3 patients. ⋯ Outcomes (Odom's criteria) after laminectomy (24 patients) and circumferential thoracic procedures (2 patients) were good to excellent in the 73% of patients with spondylosis/OPLL, in 83% with OYL, and excellent for all 3 with spondylosis/OPLL and OYL. Full recognition of thoracic or lumbar spondylosis/OPLL and OYL ensure optimal surgical planning and outcomes.
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Comparative Study
Segmental roentgenographic analysis of vertebral inclination on sagittal plane in asymptomatic versus chronic low back pain patients.
Two homogenous groups of 120 volunteers and 120 low back pain (LBP) patients, age range 20-79 years, underwent a prospective roentgenographic segmental vertebral analysis of the thoracic and lumbar spine to compare several roentgenographic parameters useful for planning spine surgery. The following roentgenographic parameters were measured: thoracic kyphosis, lumbar lordosis, sacral inclination, distal lordosis (L4-S1), inclination of each vertebra from T4-S1, and relative vertebral inclination between adjacent vertebrae. Thoracic kyphosis increased (p < 0.0001) and sacral inclination decreased (p < 0.05) with age in the control group. ⋯ Sacral inclination was significantly more in the female than in male volunteers (p < 0.05). Distal lordosis (L4-S1) represents 55% and 49% of total lumbar lordosis in controls and low back patients, respectively. Spine surgeons frequently deal with sagittal spinal deformities and the deviations of sagittal spinal curvatures and vertebral inclination in the sagittal plane, both in normal subjects and LBP patients should be clinically helpful.
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Thoracic spine stabilization after trauma or in tumor reconstruction cases frequently is performed with hook and rod internal fixation systems, the use of which is not always possible. Pelvic reconstruction plates with pedicle screw fixation offer an alternative to hooks and rods. ⋯ We further determined that the addition of pars interarticularis screws to the plate construct provided increased resistance to all loading modes. Our study indicates that plate constructs can effectively stabilize the thoracic spine.
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Degenerative spondylolisthesis (DS) is a common condition of the aging spine, but the underlying pathomechanisms remain controversial. Most previous studies focused on the role of facet-joint alignment and reported a pronounced sagittal orientation. This, however, may also be a secondary feature to the slippage. ⋯ There was no statistical difference in lumbar lordosis or L4-5 disc height between the two groups, with disc height being decreased in both groups. In group A, more gliding was associated with a further decrease in disc space, pronounced sagittal alignment of the L4-5 facet joints, and a decrease in lumbar lordosis. We concluded that further studies should focus on the analysis of spinal alignment and lower lumbar end-plate orientation to identify patients at risk for development of DS.