Effects of Pedicle Screw Fixation and Derotation During Scoliosis Surgical Correction

Abstract

Scoliosis is a three-dimensional deformity of the spine and trunk. Surgical intervention is often necessary for patients with severe curvatures. During these procedures, pedicle screws are inserted in the vertebrae and forces are applied to these screws to correctly align the spine. Forces are generally either laterally or medially directed onto the proximal exposed end of the screws. It is currently unknown how the peak forces that can be applied relate to the bone mineral density of the vertebrae. Literature is also inconclusive in regards to differences in peak forces from lateral versus medial loading. A biologically accurate fixation device has been utilized to mechanically test non-osteoporotic cadaveric vertebrae in these two loading directions. The peak failure forces were analyzed in separate medial and lateral groups and were correlated to bone mineral density.