Abstract
PurposeFree-hand pedicle screw insertion methods are widely used for screw insertion during scoliosis surgery. Preoperative knowledge about the pedicle size helps to maximize screw containment and minimize the risk of pedicle breach. Radiographs taken by a biplanar low-dose X-ray device (EOS) have no divergence in the vertical plane. The criterion validity and reliability of preoperative EOS images for pedicle size measurements in patients with idiopathic scoliosis (IS) was investigated in this study.MethodsSixteen patients who underwent surgical treatment for IS were prospectively included. Intra- and extracortical pedicle height and width measurements on EOS images were compared with reconstructed intra-operative 3D images of the isthmus of included pedicles. Secondly, intra- and interobserver reliability of pedicle size measurements on EOS images was determined.ResultsThe total number of analyzed pedicles was 203. The correlation between the EOS and 3D scan measurements was very strong for the intra- and extracortical pedicle height and strong for the intra- and extracortical pedicle width. There are, however, significant, but likely clinically irrelevant differences (mean absolute differences < 0.43 mm) between the two measure methods for all four measurements except for extracortical pedicle height. For pedicles classified as Nash–Moe 0, no significant differences in intra- and extracortical pedicle width were observed. Both intra- and interobserver reliability was excellent for all pedicle size measurements on EOS images.ConclusionThe results of this study indicate a good validity and reliability for pedicle size measurements on EOS radiographs. Therefore, EOS radiographs may be used for a preoperative estimation of pedicle size and subsequent screw diameter in patients with IS.
Highlights
Posterior spinal instrumentation and fusion with pedicle screws is a standard practice in the surgical treatment of severe idiopathic scoliosis (IS) [1,2,3]
The intracortical pedicle height was systematically measured larger on EOS images
The results of this study show a very strong correlation between the EOS and intra-operative 3D measurements for the intra- and extracortical pedicle height and a strong correlation for the intra- and extracortical pedicle width, indicating a good validity of EOS measurements
Summary
Posterior spinal instrumentation and fusion with pedicle screws is a standard practice in the surgical treatment of severe idiopathic scoliosis (IS) [1,2,3]. It is regarded as a safe and effective procedure in the majority of the patients [4]. Screw misplacements and under- or oversizing are risks. This subsequently increases the risk of neurologic or vascular injury, pedicle fracture, and screw loosening [6, 7]
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