Satoru Tanioka1, Masashi Fujimoto2, Hirofumi Nishikawa2, Katsuhiro Tanaka3, Fujimaro Ishida3, Atsushi Yamamoto2, Munenari Ikezawa4, Yusuke Kamei5, Hidenori Suzuki2, Masaki Mizuno2. 1. Department of Neurosurgery, Mie Chuo Medical Center, 2158-5 Myojin-cho, 514-1101, Hisai, Tsu, Mie, Japan. satoru.tanioka.ns@icloud.com. 2. Department of Neurosurgery, Mie University Graduate School of Medicine, 2-174 Edobashi, 514-8507, Tsu, Mie, Japan. 3. Department of Neurosurgery, Mie Chuo Medical Center, 2158-5 Myojin-cho, 514-1101, Hisai, Tsu, Mie, Japan. 4. Department of Neurosurgery, Suzuka Kaisei Hospital, 112-1 Ko-cho, 513-8505, Suzuka, Mie, Japan. 5. Department of Neurosurgery, Mie Prefectural General Medical Center, 5450-132 Oaza Hinaga, 510-8561, Yokkaichi, Mie, Japan.
Abstract
PURPOSE: A radiologic assessment method to measure position change of screw-rod constructs over time by superposing the 3‑dimensional images assists in quantitative evaluation of screw loosening. We investigated the association between position change and radiolucent zone that was commonly used for diagnosing screw loosening. METHODS: In this study 101 patients who underwent lumbar fusion were reviewed. Patient characteristics included age, sex, indications for surgery, number of fused levels, surgical procedures, and timing of follow-up computed tomography (CT, 1-5 months, 6-11 months, and ≥ 12 months). The Hounsfield unit values of L1 vertebra on preoperative CT were measured, and the radiolucent zone on each follow-up CT was evaluated. Using baseline CT on the day after surgery and follow-up CT, 3‑dimensional images of screw-rod constructs were generated and superposed. Position change was assessed by the median of the distances between the 3‑dimensional images at baseline and follow-up using the automated measurement method. Patient characteristics, the Hounsfield unit values of L1, and the amount of position change were categorized into the radiolucent zone presence and absence groups and compared. RESULTS: The medians of position change were 0.281 mm and 0.136 mm in the radiolucent zone presence and absence groups, respectively (P < 0.001 by Mann-Whitney U-test). The area under the curve for position change in identifying radiolucent zone was 0.846; the cut-off value was 1.76 mm. In multivariable analysis, position change was independently associated with radiolucent zone (adjusted odds ratio per 0.1 mm, 2.80, 95% confidence interval 1.70-4.61). CONCLUSION: Radiolucent zone was associated with position change of screw-rod constructs.
PURPOSE: A radiologic assessment method to measure position change of screw-rod constructs over time by superposing the 3‑dimensional images assists in quantitative evaluation of screw loosening. We investigated the association between position change and radiolucent zone that was commonly used for diagnosing screw loosening. METHODS: In this study 101 patients who underwent lumbar fusion were reviewed. Patient characteristics included age, sex, indications for surgery, number of fused levels, surgical procedures, and timing of follow-up computed tomography (CT, 1-5 months, 6-11 months, and ≥ 12 months). The Hounsfield unit values of L1 vertebra on preoperative CT were measured, and the radiolucent zone on each follow-up CT was evaluated. Using baseline CT on the day after surgery and follow-up CT, 3‑dimensional images of screw-rod constructs were generated and superposed. Position change was assessed by the median of the distances between the 3‑dimensional images at baseline and follow-up using the automated measurement method. Patient characteristics, the Hounsfield unit values of L1, and the amount of position change were categorized into the radiolucent zone presence and absence groups and compared. RESULTS: The medians of position change were 0.281 mm and 0.136 mm in the radiolucent zone presence and absence groups, respectively (P < 0.001 by Mann-Whitney U-test). The area under the curve for position change in identifying radiolucent zone was 0.846; the cut-off value was 1.76 mm. In multivariable analysis, position change was independently associated with radiolucent zone (adjusted odds ratio per 0.1 mm, 2.80, 95% confidence interval 1.70-4.61). CONCLUSION: Radiolucent zone was associated with position change of screw-rod constructs.
Authors: Samuel Jang; Peter M Graffy; Timothy J Ziemlewicz; Scott J Lee; Ronald M Summers; Perry J Pickhardt Journal: Radiology Date: 2019-03-26 Impact factor: 11.105