Radiological and clinical outcome of screw placement in adolescent idiopathic scoliosis: evaluation with low-dose computed tomography

Abstract

Posterior corrective surgery using ''all pedicle screw construct'' carries risk of neurovascular complications. The study aims were to assess the screw placement in patients with adolescent idiopathic scoliosis using CT with low-radiation dose, and to evaluate the clinical outcome in patients with misplaced pedicle screws. CTs of 49 consecutive patients (873 screws, 79% thoracic) were retrospectively evaluated by two independent radiologists. A new grading system was developed to distinguish between lateral, medial and anterior cortical perforations, endplate perforation and foraminal perforation. The grading system is based on whether the cortical violation is partial or total rather than on mm-basis. The overall rate of screw misplacement was 17% (n = 149): 8% were laterally placed and 6.1% were medially placed. The rates of anterior cortical, endplate and foraminal perforation were 1.5, 0.9, and 0.5%, respectively. Lateral cortical perforation was more frequent in the thoracic spine (P = 0.005), whereas other types of misplacement including medial cortical perforation were more frequent on the left and the concave side of scoliotic curves (P = 0.002 and 0.003). No neurovascular complications were reported. The association between the occurrence of screw misplacement and the Cobb angle was statistically significant (P = 0.037). Misplacements exceeding half screw diameter should be classified as unacceptable. Low-dose CT implies exposing these young individuals to a significantly lower radiation dose than do other protocols used in daily clinical practice. We recommend using low-dose CT and the grading system proposed here in the postoperative assessment of screw placement.

Adolescent idiopathic scoliosis treated with posteromedial translation: radiologic evaluation with a 3D low-dose system

“…The Values are presented with standard deviation method does not require additional examination to assess the axial plane, and vertebral axial rotations, in particular, can be assessed accurately in routine pre-and postoperative clinical use with greatly reduced exposure to ionizing radiation [12]. As a matter of fact, the mean effective dose calculated in the current study was 6 times lower than the one reported by Abul-Kasim [24,27] with low-dose CT. The device is expensive, but the cost of an examination remains the same as the one of a conventional full spine radiograph in our institution.…”

Five-year clinical and radiographic outcomes using pedicle screw only constructs in the treatment of adolescent idiopathic scoliosis

“…Prior series have reported complication rates using pedicle screw constructs, but most have revolved around placement of screws and not the clinical complications [32][33][34]. Our series only had three malpositioned screws, but these were not evaluated by post-operative CT imaging.…”

Use of computed tomographic reconstruction to establish the ideal entry point for pedicle screws in idiopathic scoliosis

“…Computed tomography (CT) scan has also been used for preoperative measurement and postoperative assessment in spine surgery [11,12]. With advances in equipment and scanning parameter settings, single-dose radiation has reached an acceptable range [13].…”