Elsevier

World Neurosurgery

Volume 110, February 2018, Pages e271-e280
World Neurosurgery

Original Article
Efficacy of Using Intermediate Screws in Short-Segment Fixation for Thoracolumbar Fractures: A Meta-Analysis of Randomized Controlled Trials

https://doi.org/10.1016/j.wneu.2017.10.157Get rights and content

Background

Some studies have reported that the conventional intersegmental pedicle screws (4-screw fixation [4S]) device for thoracolumbar fractures was associated with inadequate reduction of fractured vertebrae, insufficient correction of kyphosis, and implant failure. Recently, a series of biomechanical studies has confirmed that the addition of intermediate fixation screws (6-screw fixation [6S]) could provide stronger fixation and better reduction of fractured vertebrae. Nevertheless, the clinical and radiologic efficacy of the additional intermediate screws remains unclear.

Methods

A meta-analysis of randomized controlled trials was used to compare clinical and radiologic outcomes and complications of posterior pedicle screws combined with intermediate screws fixation versus conventional intersegmental pedicle screw fixation. We comprehensively searched MEDLINE, OVID, and Springer according to a search strategy, selecting articles based on inclusion criteria, and extracted data from these reports. Risk of bias in included studies was assessed. Pooled estimates and corresponding 95% confidence intervals were calculated.

Results

Six randomized controlled trials involving 310 patients were evaluated in this meta-analysis. Pooled estimates showed statistically similar baseline characteristics, hospital stays, postoperative visual analog scale scores, and infection rates between the 4S group and the 6S group. The 6S group had significantly less correction loss of segmental angle and of anterior vertebral height compression, and lower implant failure rate. The 6S group also showed a slightly longer operative time and more blood loss than did the 4S group.

Conclusions

Based on our analysis, the combined intermediate screws fixation technique was associated with significantly improved radiologic outcomes but did not seem to compromise other perioperative outcomes.

Introduction

Thoracolumbar fractures are one of the most common types of traumatic fractures, accounting for 30%–60% of all spinal fractures.1 Nearly 60%–70% of thoracolumbar fractures occur in the T11-L2 region.2, 3 Acute thoracolumbar fracture is often associated with kyphotic deformity and neurologic deficits. Posterior intersegmental pedicle screws fixation (1 level above and 1 level below the fracture level: 4-screw fixation [4S]) is the classic surgical method and is used widely in treating thoracolumbar fractures. It can restore spinal stability, correct kyphotic deformities, and indirectly decompress the spinal canal. However, some studies have reported that the conventional intersegmental pedicle screw device was inadequate to reduce the fractured vertebrae and correct the kyphosis and was associated with an unacceptable rate implant failure.4, 5, 6

The biomechanical study with intermediate screw fixation (6-screw fixation [6S]) was first performed by Dick et al.7; it showed that the addition of intermediate screws could create a more rigid construct and improve the stability of the fractured vertebrae compared with a conventional intersegmental pedicle screw fixation. Later, a series of biomechanical studies8, 9, 10, 11 also confirmed that the additional use of intermediate screws could significantly improve the biomechanical stability and construct stiffness. Nevertheless, the clinical and radiologic efficacy of additional intermediate screws has remained unclear.

Recently, several randomized controlled trials (RCTs) have compared the clinical and radiologic efficacy of posterior pedicle screws combined with intermediate screw fixation versus conventional intersegmental pedicle screw fixation.12, 13, 14, 15, 16, 17 The purpose of this meta-analysis was to summarize and identify the evidence from these RCTs to assess the effectiveness of intermediate screws as a supplement to posterior short-segment pedicle screw fixation for thoracolumbar fractures.

Section snippets

Search Strategy and Inclusion Criteria

This meta-analysis was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. A systematic literature search was conducted up to January 2017 using MEDLINE, OVID, and Springer. We screened the titles and abstracts by combining the term “thoracic fracture(s),” “thoracolumbar fracture(s),” “lumbar fracture(s),” or “burst fracture(s),” with each of the following key words: “intermediate screw,” “additional screw,” “index level,” “index

Literature Search

The search strategy (Figure 1) identified 715 potential studies from the databases. A total of 709 articles were excluded according to our criteria. The reasons for exclusion consisted of inappropriate topics (n = 698), non-RCTs (n = 6), reviews (n = 2), and biomechanical studies (n = 3). No additional study was obtained after reference review. Six RCTs were selected and analyzed.12, 13, 14, 15, 16, 17

Risk of Bias Assessment

Two trials described adequate methods of random sequence generation.13, 17 In 2 quasi-RCTs,

Discussion

Our meta-analysis showed statistical differences in operative time together with blood loss occurring between the 4S and 6S groups. The operative time in the 6S group was 3.7 minutes longer compared with that in the 4S group and blood loss in the 6S group was 7.2 mL greater compared with that in the 4S group. Although the difference was statistically significant, the clinical difference was not obvious. This finding is likely to be ascribable to the additional pedicle screws inserted into the

Conclusions

In this meta-analysis, we compared the clinical and radiologic efficacy of posterior pedicle screws combined with intermediate screw fixation versus conventional intersegmental pedicle screw fixation. Our analysis showed that the combined intermediate screw fixation technique was associated with better maintenance or correction of the kyphotic angle and the height of the fractured vertebrae postoperatively, better reduced correction loss at follow-up, a lower implant failure rate, and slightly

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    • Comparison of Polyaxial or Poly/Monoaxial Mixed Screw Fixation for Treatment of Thoracolumbar Fractures with O-Arm Navigation: A Case–Control Study

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      Dick et al.18 found that intermediate screw for short-segment fixation of thoracolumbar fractures could create a more rigid construct and improve the stability compared with 4-screw fixation in their biomechanical study. Tong et al.19 conducted a meta-analysis of randomized controlled trials, which showed that intermediate screw fixation could achieve better correction of kyphotic angle and height of fracture vertebrae versus 4-screw fixation. However, the optimal screw design for the fixation of injured and adjacent vertebrae remains controversial, and no clinical study has been conducted to compare different screw fixation methods.

    • Comparison of Four Different Posterior Screw Fixation Techniques for the Treatment of Thoracolumbar Junction Fractures

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      One of the objective criteria of radiologic evaluation of thoracolumbar junction fractures is FVCA with evaluation of the compression angle of the fractured vertebra. In a meta-analysis by Aly et al.,18 they observed that a significant correction was achieved in FVCA, similar to that observed in LKA, with short-segment instrumentation with screw augmentation at the fracture line, and that this correction was sustained in the long term.15,17,21,22 Consistent with the literature, the present study observed no statistically significant difference in FVCA values among the 4 Groups when postoperative radiographs were compared with final follow-up visit radiographs.

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    Conflict of interest statement: This work is supported by Wenzhou Science and Technology Bureau Foundation (grant number 20160363).

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