Level-based analysis of screw loosening with cortical bone trajectory screws in patients with lumbar degenerative disease

Abstract

This study aimed to verify the relationship between the number of fusion level and the risk of screw loosening by using cortical bone trajectory (CBT) screws in patients with lumbar degenerative disease. We retrospectively reviewed the serial plain radiograph images of lumbar degenerative disease patients who had undergone posterior fixation and fusion surgery with CBT from 2014. All included patients should have been followed-up with computed tomography scan or plain radiograph for at least 6 months after operation. We individually evaluated the prevalence of screw loosening according to each vertebral level. We also determined whether the number of screw fixation affected the prevalence of screw loosening and whether S1 fixation increased the risk of screw loosening. The screw-loosening rates were high at the S1 level. Moreover, although fixation involved to S1, the loosening rates evidently increased (Fisher exact test, P = .002 ∗∗ ). The screw-loosening rate was 6.56% in 2 level fusion. However, it increased with the number of fusion levels (3 level: 25.00%, 4 level: 51.16%, and 5 level: 62.50%). To investigate if the number of fusion level affected the S1 screw loosening, we classified the cohort of patients into either involving S1 (S1+ group) or not (S1– group) according to different fusion levels (Table 3 ). The screw loosening between 2 group in 2 (5.56% vs 6.98%) and 3 fusion level (26.32% vs 22.73%) did not exhibit any significant difference. Interestingly, significantly high screw loosening was found in 4 fusion level (60.00% vs 15.38%), indicating that the higher fusion level (4 level) can directly increase the risk of S1 screw loosening. Our data confirmed that the screw-loosening rate increases rate when long segment CBT fixation involves to S1. Therefore, in case of long-segment fixation by using CBT screw, surgeons should be aware of the fusion level of S1.

A nomogram for predicting screw loosening after single-level posterior lumbar interbody fusion utilizing cortical bone trajectory screw: A minimum 2-year follow-up study

“…Likewise, good results have been found in literature works reporting the application of CBT screw in osteoporosis lumbar spine (1,5,6). The main role of the screw in lumbar fusion is to reduce the motion of the spine and to conduct the stabilization, whereas screw loosening is observed in quite a few literature works (7)(8)(9). As reported, the incidence of screw loosening in TPS was 1%-60% (7,10,11), and risk factors were related to osteoporosis, sacrum instrument, excessive load, and local high strains; however, it was not unified.…”

“…CBT screw conducts a comparable fixation to TPS according to the characteristic, and it may reduce the risk of screw loosening due to the loading resistivity of cortical bone of the pedicles. Nevertheless, the screw loosening rate was still observed to be 62.5% (9,(12)(13)(14), and the risk factors were also uncertain. This leads to consideration of the differences in risk factors for screw loosening between CBT screw and TPS.…”

“…Screw loosening in both the TPS and CBT screw may require revision surgery due to symptomatic spinal instability and instrument failure (9,11,15,16); thus, comprehension of screw loosening is essential. Previous studies were researched, and we found that few studies have concentrated on CBT screw loosening, or most of them lacked long-term follow-up and sufficient evidence.…”

A Biomechanical Study on Cortical Bone Trajectory Screw Fixation Augmented With Cement in Osteoporotic Spines

“…14 Besides, the CBT screw loosening rate was raised with the increase of fixed spine segments. 15 Therefore, it is necessary to further increase the CBT screw fixation stability, especially in the face of the increasing number of osteoporosis patients.…”

A Nomogram for Predicting Screw Loosening after Single-Level Posterior Lumbar Interbody Fusion utilizing Cortical Bone Trajectory Screw: A Minimum 2-year Follow-up Study

“…Likewise, good results were shown in literatures reporting the application of CBT screw in osteoporosis lumbar spine 1 5 6 . The main role of screw in lumbar fusion is to reduce the motion of spine and to conduct the stabilization, whereas, screw loosening is observed in quite a few literatures [7][8][9] . As reported, the incidence of screw loosening in TPS was 1%-60% 7 10 11 , and risk factors were related to osteoporosis, sacrum instrument, excessive load and local high strains, etc., however, it was not uni ed.…”