Comparison of Hidden Blood Loss Between Cortical Bone Trajectory Screw Fixation and Traditional Pedicle Screw Fixation

Abstract Objective: This research aimed at examining the volume of hidden blood loss (HBL) in lumbar fusion surgery with two kinds of screw implanting techniques and evaluating HBL-related factors in the patient population receiving lumbar fusion surgeryMethods: A retrospective study was conducted targeting 104 patients with lumbar degenerative diseases and treated with TLIF from January 2017 to December 2018, and the CBT (cortical bone trajectory) technique and conventional PS (pedicle screw) technique were applied to 45 and 59 patients, respectively. The collected data covered patients’ weight, height, BMI index, and operation time. It was followed by the recording of preoperative and postoperative hematocrit (HCT) of patients, based on which the blood loss was calculated by Gross’s formula. Results: The CBT and PS groups presented no significant difference in demographic characteristics (p > 0. 05), but the average HBL of 280±227 mL and 298±232 mL as well as the average TBL of 603±232 mL and 728±321 mL, respectively. It indicated the difference of the two groups in TBL, but no significant difference in HBL. In addition, an association of HBL of two screw techniques with operation time, concomitant disease and age was found from the data analysis.Conclusion: Large total blood loss incurred in lumbar fusion surgery, specifically with a lower value by the CBT technique than by the PS technique. Nonetheless, HBL occupied a large part of the total blood loss and it was identified in both groups. Thus, a good understanding of HBL will improve postoperative rehabilitation and guarantee patients’ safety.