Stereoradiography imaging motion artifact: does it affect radiographic measures after spinal instrumentation?

Purpose: Stereoradiography imaging (SRI) is an accurate and reliable low-dose radiographic method. However, patients must remain motionless during image acquisition. Motion artifacts are frequently noted. The aims of the study were to determine the incidence of the SRI motion artifact and assess if motion during SRI acquisition affects radiographic measurements. Methods: In this retrospective study, 198 patients with spinal instrumentation had biplanar SRI radiographs performed, of whom 39 had concomitant conventional radiographs. Eight coronal and sagittal spinal parameters were independently measured on SRI and conventional radiographs for the 39 patients by 2 observers. Inclusion criteria were: presence of spinal instrumentation of more than six levels and an SRI motion artifact identified on the coronal and/or the sagittal views on either the spinal rods or on the limbs. Means were compared between both types of radiographs using the Student’s t test; intraclass correlation coefficients (ICCs) were used for intraobserver reproducibility and interrater reliability. Results: A motion artifact was identified in 19.7 % (n = 39, mean age 19.5 ± 1.7 years) of the cases. There were no differences in any of the coronal or sagittal plane measurements between SRI and X-rays. Intraobserver reliability and interrater reproducibility was high (range 0.81–0.98). Conclusions: Motion artifact during full-spine stereoradiography imaging acquisition is frequent, but does not affect spinal measurements. SRI with a motion artifact can be used to produce reliable measurements of the sagittal and coronal parameters. Some SRI images with a motion artifact may suggest loss of fixation or bending of the rods. However, after becoming familiar with the appearance of the motion artifact, repeat radiographs are rarely indicated. IRB number: 14-004872. Level of evidence: Level IV.