The use of computer tomography for preoperative planning and outcome assessment in surgical treatment of idiopathic scoliosis with pedicle screw based constructs - case presentation.

BACKGROUND In recent years pedicle screw based constructs have been increasingly used in the operative management of scoliosis. The current principles of screw placement are based on normal anatomy and therefore may not be applicable in cases of severe vertebral deformity due to torsion. The aim of this study was to evaluate the usefulness of computer tomography (CT) in preoperative planning and outcome assessment in operative management of idiopathic scoliosis with severe internal vertebral deformity. MATERIAL AND METHODS The study presents our own experiences based on analysis of diagnostic and therapeutic decision-making in two patients treated surgically due to Lenke type 1A idiopathic scoliosis. Due to extensive vertebral rotation and radiological appearance suggesting thin pedicles, spine CT with 3D reconstruction was performed as part of extended preoperative work-up in order to determine screw length and diameter, the point of screw introduction and angle of introduction in three planes. Vertebral rotation was evaluated according to the Aaro-Dahlborn method. Segments were also identified where pedicle screws could not be applied due to severe rotation or small pedicle diameter. RESULTS Preoperative planning of screw placement enabled safe and accurate screw application, as confirmed by postoperative spine CT evidence. Satisfactory correction was achieved in both patients in the coronal and frontal planes. CONCLUSIONS CT allows detailed preoperative planning of scoliosis surgery and identification of segments in which pedicle screws cannot be safely placed. This may lower the incidence of complications associated with inaccurate pedicle screw placement.