Incidence of Screw Loosening in Cortical Bone Trajectory Fixation Technique between Single- and Dual-Threaded Screws.

Chao-Hsuan Chen,Hsiang-Ming Huang,Der-Cherng Chen,Der-Yang Cho,Chih-Hsiu Tu,Da-Tian Bau,Hao-Yu Chuang,Han-Chung Lee

doi:10.3390/medicines8090050

Abstract

Purpose: This study aims to elucidate the radiological outcome after Cortical bone trajectory (CBT) screw fixation and whether dual-threaded (DT) screws should be used in the fusion surgery. Methods: 159 patients with degenerative lumbar disorder who had undergone midline lumbar inter-body fusion surgery by CBT screw-fixation technique (2014 to 2018). Patient subgroups were based on single-threaded (ST) or DT screw, fixation length, as well as whether fixation involved to sacrum level (S1). Serial dynamic plain films were reviewed and an appearance of a halo phenomenon between screw–bone interfaces was identified as a case of screw loosening. Results: 29 patients (39.7%) in ST group and 10 patients (11.6%) in DT group demonstrated a halo phenomenon (p < 0.0001 ****). After subgrouping with fixation length, the incidence rates of a halo phenomenon in each group were 11.1%:3% (ST-1L vs. DT-1L), 37%:13.8% (ST-2L vs. DT-2L), and 84.2%:23.5% (ST-3L vs. DT-3L). Among the 85 patients with a fixation involved in S1, 26 patients (52%) with single-threaded screw (STS group) and 8 patients (22.8%) with dual-threaded screw (DTS group) demonstrated a halo appearance (p = 0.0078 **). After subgrouping the fixation level, the incidence of a halo appearance in each group was 25%:0% (STS-1L vs. DTS-1L), 40.9%:26.3% (STS-2L vs. DTS-2L), and 87.5%: 30% (STS-3L vs. DTS-3L). Conclusion: Both fixation length and whether fixation involved to S1 contribute to the incidence of screw loosening, the data supports clinical evidence that DT screws had greater fixation strength with an increased fixative stability and lower incidence of screw loosening in CBT screw fixation compared with ST screws. Level of evidence: 2.

Highlights

Spinal fusion is currently the standard surgical treatment for various lumbar spinal disorders
We found that the incidences of halo phenomenon in subgroups ST-1L vs. DT-1L, ST-2L vs. DT-2L, and ST-3L vs. DT-3L were 11.1%:3% (Fisher’s exact test, p = 0.3179), 37%:13.8% (Fisher’s exact test, p = 0.0410 *), and 84.2%:23.5% (Fisher’s exact test, p = 0.0006 ***), respectively (Figure 4), suggesting the DT group can reduce the incidence rates of a halo phenomenon, resulting from the greater of fixation length
Moraenfyamapilpiaror atochmesoshtasvpeinbeeesnuragdevoon-s. cTarteaddiitniotnhael ppaesdticdleecsacdreesw, afinxdatpioonstewriiothr alupmprboaarcihnetserabroedmyofruesfioamn uilisauratlolymreoqsut isrpeisnleosnugre-r gienocnissi.oTnraadnditiwonidalepdeidssicelcetisocnreowf tfhixeamtiounscwuliathr slturmucbtaurrein, wterhbicohdymfauysicoanusuesudaalmlyargeeqtuoirtehse lopnogsteerroinmciesdioianl annedrvwe ibdreandcishscercotisosninogftthheefmacuestcjouilnartssatrnudctiunrteu,rwnhleicahdmtoapyrcoalounsegeddamhoasgpeithotsoapstlihipnzeiaatlaptilsooiuzsnratgeatrienoordnymctaehhndardiotanwlcinhacerslorofivnwreisc-tbbldraoaecwnskcc-rhbpiabacciernkdo.spbCsayiBninSTga. tsnChctreBoenTfwai cseiectnrtasejleow.riitnniitons2ns0ae0inrs9tdi;aosinnnuocitvhsueraalntfneuleocsahvidonenlitqoftuuepecsrhiioonnnlciorqnteueagcesehedi-dn nique in spinal surgery that was first described by Santoni et al in 2009; such a technique increased the uniaxial yield pullout load by 30% compared to traditional pedicle screws (TPS) [3]

Summary

Introduction

Spinal fusion is currently the standard surgical treatment for various lumbar spinal disorders. Pedicle screw fixation along the axis of the pedicle of the lumbar arch is the most common and reliable procedure in fusion surgery. With this entry point and route, the screw contacts the cancellous bone of the pedicle and vertebral body instead of the cortical bone of the pedicle. Cortical bone trajectory (CBT) screw insertion is a novel fusion technique in spinal surgery that was first described by Santoni et al in 2009; such a technique increased the uniaxial yield pullout load by 30%, compared with traditional pedicle screws (TPS) [3]. Given the differences in entry point and trajectory compared with the conventional pathway, this technique minimizes the engagement of trabecular bone within the pedicle and offers greater amount of screw-cortical bone interception. Whether differently designed thread screws are suitable for CBT in clinical use remains unclear

Objectives

Methods

Findings

Discussion

Conclusion