Efficacy and Safety of Cement Augmented Fenestrated Screws in the Surgery With Posterior Approach for Spinal Metastases&nbsp;&nbsp;
Authors: Feng Qi , Wang Donglai , Zang Zibo , Feng Jiangang 
Published: November 2020

Abstract
Objective: To investigate the efficacy and safety of cement augmented fenestrated screws in the posterior approach for spinal metastases.Methods: A total of 52 patients with spinal metastases who underwent surgery with posterior approach separation and internal fixation with pedicle screw in the Department of Orthopaedics of the Fourth Hospital of Hebei Medical University from January 2015 to January 2017 were analyzed retrospectively. There were 28 cases in the cement augmented pedicle screw group and 24 cases in the conventional pedicle screw group. The clinical data, preoperative and postoperative pain, and neurological function between the two groups were compared. After follow-up, every 3 months, the local progression-free survival time of patients in the two groups was recorded to explore the safety of cement augmented pedicle screws in posterior separation of spinal metastases, and to analyze the difference in efficacy between the two groups.Results: There were no significant differences in sex, age, segments of the affected vertebra, Tomita score, Tokuhashi score, spinal instability neoplastic score (SINS), intraoperative blood loss and average postoperative hospital stays between the two groups. The average operation time was 161 ± 21 minutes in the cement augmented pedicle screw group and 135 ± 19 minutes in the conventional pedicle screw group, with a statistically significant difference. A total of 218 screws were implanted in the 28 patients of the cement augmented pedicle screw group, with an average of 1.3 ± 0.4 ml of cement injected into each screw. There was 1 case of cerebrospinal fluid leakage in each of the two groups, and no incision hematoma formation or infection occurred. There was no symptomatic pulmonary cement embolism in the cement augmented pedicle screw group. The preoperative VAS scores were not statistically different between the two groups. However, the VAS scores in the two groups decreased 3 months after surgery, which were 2.93 ± 1.33 and 4.17 ± 1.34, respectively, with statistical significance. The recovery of Frankel grading was found in 84.6% of all patients (44 cases in 52 patients), but there was no significant difference in Frankel grades between the two groups before and 3 months after surgery. During the follow-up period of 6-24 months, there were 10 cases of adjacent segmental metastasis (2 cases in cement augmented pedicle screw group and 8 cases in conventional pedicle screw group) and 8 cases of internal fixation failure (1 case cement augmented pedicle screw group and 7 cases in conventional pedicle screw group). The difference was statistically significant. Compared with the conventional pedicle screw group, the conventional pedicle screw group had a longer survival time of progression-free in the local and adjacent segments, and the difference was statistically significant. Conclusion: The application of cement augmented pedicle screw in surgery of spinal metastases with the posterior approach is safe, and the pain score decreases more obviously 3 months after surgery. It can effectively reduce the adjacent segmental metastasis and failure rate of internal fixation and prolong the local progression-free survival time.