Bending rod is unnecessary in single-level posterior internal fixation and fusion in treatment of lumbar degenerative diseases

Xiao Han,Xin Chen,Zheng Li,Kuan Li,Shugang Li

doi:10.1186/s12893-021-01386-x

Abstract

BackgroundBending rod is a routine in lumbar fusion and fixation surgery, but there is no study investigating whether bending rod in one level is necessary.MethodsPatients receiving 1 level lumbar fixation and fusion between May 2018 and September 2020 were included with a minimum 6-month follow-up. The routine of bending rod was omitted during fixation. Preoperative and postoperative radiological parameters were compared.ResultsThere were 67 patients included in the study. Segment lordosis angle increased obviously from 10° (1–39°) to 14° (2–30°) immediately after operation (p = 0.000). T5-T12 increased from 22.97 ± 12.31° to 25.52 ± 11.83° by the 3rd months after surgery (p = 0.011). SS decreased from 35.45 ± 10.47 to 32.19 ± 11.37 in 6-month follow-up (p = 0.038), and PI dropped from 56.97 ± 14.24 to 53.19 ± 12.84 (p = 0.016). ROM of SLA decreased from 4.13 ± 3.14° to 1.93 ± 1.87° at that time point (p = 0.028). Those changes were not seen at 12-month follow-up. No evidence of adjacent vertebral disc degeneration was observed at any time point.ConclusionsNo sagittal imbalance, dynamic instability or adjacent vertebral degeneration was observed by the 12th month after single-segment posterior lumbar fusion with the use of unbent rods. Bending rod could be omitted in 1-level lumbar fusion to simplify the procedure and reduce operating time.

Highlights

Bending rod is a routine in lumbar fusion and fixation surgery, but there is no study investigating whether bending rod in one level is necessary
lumbar lordosis angle (LLA) is a component of sagittal spino-pelvic parameters, the restoration of which plays a key role in maintaining balance and preventing adverse events such as long-lasting postoperative low back pain, failure and adjacent vertebral diseases (AVD) [3, 4]
sacral slope (SS) decreased from 35.45 ± 10.47 to 32.19 ± 11.37 (p = 0.038), and pelvic incidence (PI) dropped from 56.97 ± 14.24 to 53.19 ± 12.84 (p = 0.016)

Summary

Introduction

Bending rod is a routine in lumbar fusion and fixation surgery, but there is no study investigating whether bending rod in one level is necessary. Due to physiological lumbar curvature in the sagittal plane, the straight rods are always bent to curve to simulate the lumbar lordosis angle (LLA) [2]. LLA is a component of sagittal spino-pelvic parameters, the restoration of which plays a key role in maintaining balance and preventing adverse events such as long-lasting postoperative low back pain, failure and adjacent vertebral diseases (AVD) [3, 4]. Previous studies focused mainly on the significance of bending rod in multi-levels lumbar fusion [5]. It is a general trend to cater the natural curve of lumbar spine without spending too much time preparing the bend rod, and computerassisted pre-bent system has been developed to achieve this goal [6]

Methods

Results

Conclusion