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Fig. 2 | BMC Musculoskeletal Disorders

Fig. 2

From: A novel posterior multiple screws distraction reducer system versus anterior release, posterior internal distraction, and subsequent spinal fusion for severe scoliosis

Fig. 2

Procedures of MSDR correction technique: a With the spine exposed posteriorly, pedicle screws are inserted. Provisional rods are attached to the proximal, apical, and distal segments on the concave side of the spine. b The first maneuver addresses the coronal deformity with consistent distraction between the proximal and distal segments. Multiple rounds of distraction can be performed to take advantage of the viscoelastic properties of biological tissues. c A derotation coupler enables axial derotation of the spine and rib cage. The shaft connected with a cantilever lifts the middle provisional rod to restore thoracic kyphosis. The second step is to restore thoracic kyphosis and is performed by rotating the derotation coupler through a threaded shaft. The shaft connected with a cantilever lifts the middle provisional rod. Axial derotation of the spine and rib cage is also achieved in this step. d Once sufficient correction has been achieved, the permanent rod is measured, cut, and undercontoured for the convex side of the spine to push down toward the apex and improve rotational deformity. Spinal compression on the apical segments is also performed for further coronal correction. e The permanent rod is measured, cut, and contoured for the concave side of the spine. Overcontouring the concave rod in thoracic kyphosis helps further restore the thoracic sagittal plane. The apical segments can be translated posteriorly to correct thoracic hypokyphosis and laterally to correct coronal deformity

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