Modern scoliosis techniques: the use of thoracic pedicle screws for the correction of spinal deformity

Abstract

The surgical treatment of scoliosis continues to evolve from its infancy in the late 1950s with Harrington rod instrumentation to the segmental thoracic pedicle screw constructs that are now being used. Thoracic pedicle screw fixation provides true segmental correction but also has some inherent disadvantages. Ideally, scoliosis treatment should correct sagittal, coronal and transverse or axial planes with rigid fixation minimizing fusion levels. The primary advantage of thoracic pedicle screws when compared with other constructs appears to be improved coronal correction, decreased pseudarthrosis rates, lower implant failure rates, three-column fixation, and the ability to correct the scoliotic deformity in all three planes. Potential disadvantages of all thoracic screw constructs involve the lordosing effect of posterior instrumentation systems that may significantly decrease thoracic kyphosis. Multiple screw placement techniques range from an all free-hand technique to image guidance. The free-hand technique with a straight-forward trajectory has been shown to have favorable pullout strength and insertional torque compared with the anatomic technique. Recent literature also has demonstrated that thoracic pedicle screws are so effective that they may replace the need for anterior surgery in adult scoliosis surgery. With proper technique placement, thoracic pedicle screws are safe and can provide maximal clinical efficacy. A review of thoracic pedicle anatomy, surgical techniques and segmental fixation constructs is provided in this review.