Spinal alignment in surgical, multisegmental, transpedicular correction of adolescent idiopathic scoliosis

Abstract

SummaryThe objective of this study was to discuss the variables influencing alignment mechanisms of the spine, with particular consideration of post-surgical alignment in adolescent idiopathic scoliosis. The analysis is based on information currently available in the literature, and on the authors’ own experience, which includes surgical material from over 2200 cases of idiopathic scoliosis.Over 50% of cases of adolescent idiopathic scoliosis are decompensated before surgical treatment. Spinal alignment is most significantly influenced by the position of the pelvis. Surgical restoration of lumbar lordosis is more important than attempting to restore thoracic kyphosis in the sagittal plane. The sagittal profile has an essential impact on spinal alignment. The same curves in the coronal plane can have various 3-dimensional configurations. Clinical difficulties in the assessment of thoracic kyphosis and lumbar lordosis result from the fact that they undergo constant change with age. Thoracic hypokyphosis diagnosed before surgery is a very frequent symptom of curve progression. The presence of proximal (thoraco-thoracic) and distal (thoraco-lumbar) junctional kyphosis is very important for planning the scope of spondylodesis.The natural tendency of the spine for alignment (compensation) after surgery nowadays occurs more naturally by applying derotational forces through pedicle screws, compared to the distraction devices (eg, Harrington rod) used in the past.

Influence of patient rotational malpositioning on pelvic parameters assessed on lateral radiographs

“…9 These parameters are of paramount importance in the radiographic evaluation of a large range of spinal pathologies such as spondylolisthesis, adolescent idiopathic scoliosis, adult spinal deformity, but also degenerative conditions. 10,11 Although these parameters are easily accessible on standard full-spine sagittal radiographs, their measurements can be biased by a number of factors including the two-dimensional (2D) nature of the radiograph, as it projects three-dimensional structures onto a bi-dimensional plane, and the potential malpositioning of patients during radiograph acquisition. Therefore, it is crucial to quantify the errors associated with this technique, especially those related to patient malpositioning during radiograph acquisition.…”

Feasibility and accuracy of new insertion technique of S1 transpedicular screw. Computed tomography-based morphometric analysis

“…In the sagittal reconstruction, we measured: (1) The angle between the screw and the superior S1 end-plate; and (2) The distance of the screw thread ends, dorsal and ventral, to the superior S1 end-plate. Dorsal screw thread end was defined as the entry point into the sagittal plane.…”

“…Pedicle screw fixation is the mainstay of stabilization in the thoracolumbar spine [1][2][3][4]. The technique requires the proper identification of entry-point followed by finding the optimal trajectory in order to achieve sufficient mechanical strength and structural risk minimization.…”

Radiographic Parameters of Spine Coronal Plane Before and After the Surgical Adolescent Idiopathic Scoliosis Correction

“…The essence of surgical treatment is not maximal correction of the spine in the coronal plane, but rather safe derotation leading to restoration of spinal alignment after surgery [12]. Alignment is the state of a person standing or sitting with the trunk situated in the centre of gravity, which runs (in a standing position) centrally to a quadrangle of support by the position of the feet (linear alignment) [13].…”