A Lower T1 Slope as a Predictor of Subsidence in Anterior Cervical Discectomy and Fusion with Stand-Alone Cages

Lee, Su Hun; Lee, Jung Hoon; Sung, Soon Ki; Son, Dong Wuk; Lee, Sang Weon; Song, Geun Sung

doi:10.3340/jkns.2017.0404.001

Cited by 15 publications

(17 citation statements)

References 32 publications

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“…Various studies have described various indices to predict LCL in patients undergoing laminoplasty. [ 18 19 20 21 ] The indices which may play an important role in predicting LCL are described in Table 1 and Figure 1 .…”

Section: Methodsmentioning

confidence: 99%

Factors predicting loss of cervical lordosis following cervical laminoplasty: A critical review

Alam

Sharma

Borkar

et al. 2020

J Craniovert Jun Spine

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Background: Laminoplasty is a method of posterior cervical decompression which indirectly decompresses the spinal column. Unfortunately, many patients undergoing laminoplasty develops postoperative loss of cervical lordosis (LCL) or kyphotic alignment of cervical spine even though they have sufficient preoperative lordosis which results in poor surgical outcome. Objective: We would like to highlight the relationship between various radiological parameters of cervical alignment and postoperative LCL in patients undergoing laminoplasty. Methods: We performed extensive literature search using PubMed, Google Scholar, and Web of Science for relevant articles that report factors affecting cervical alignment following laminoplasty. Results: On reviewing the literature, patients with high T1 slope have more lordotic alignment of cervical spine preoperatively. They also have more chances of LCL following laminoplasty. C2–C7 sagittal vertical axis (SVA) has no role in predicting LCL following laminoplasty though patients with low T1 slope (≤20°) and high C2–C7 SVA (>22 mm) had correction of kyphotic deformity following laminoplasty. C2–C7 lordosis, Neck Tilt, cervical range of motion, and thoracic kyphosis has no predictive value for LCL. Lower value of T1 slope (T1S-CL) and CL/T1S has more incidence of developing LCL following laminoplasty. The role of C2–C3 disc angle has not yet been evaluated in patients undergoing laminoplasty. Dynamic extension reserve determines the contraction reserve of SPMLC and lower dynamic extension reserve is associated with higher chances of LCL following laminoplasty. Conclusions: Cervical lordotic alignment is important in maintaining cervical sagittal balance which ultimately is responsible for global spinal sagittal balance and horizontal gaze. Among various radiological parameters, T1 Slope has been reported to be the most important factor affecting cervical alignment following laminoplasty.

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Section: Methodsmentioning

confidence: 99%

Factors predicting loss of cervical lordosis following cervical laminoplasty: A critical review

Alam

Sharma

Borkar

et al. 2020

J Craniovert Jun Spine

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“…In contrast, the autogenous or allogenous bone graft has similar or less elasticity than the surrounding bone, therefore collapse is more frequent than subsidence. Many studies have already reported the risk factors of subsidence in PEEK/titanium cage, such as cage type [2,8,21], cage location [17], intra-operative distraction [7], end-plate preparation [14], and cervical sagittal alignment [12,13]. However, currently there are very limited studies about the absorption of an allograft.…”

Section: Discussionmentioning

confidence: 99%

Risk Factors of Allogenous Bone Graft Collapse in Two-Level Anterior Cervical Discectomy and Fusion

Woo

Son

Lee

et al. 2019

J Korean Neurosurg Soc

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Objective Anterior cervical discectomy and fusion (ACDF) is commonly used surgical procedure for cervical degenerative disease. Among the various intervertebral spacers, the use of allografts is increasing due to its advantages such as no harvest site complications and low rate of subsidence. Although subsidence is a rare complication, graft collapse is often observed in the follow-up period. Graft collapse is defined as a significant graft height loss without subsidence, which can lead to clinical deterioration due to foraminal re-stenosis or segmental kyphosis. However, studies about the collapse of allografts are very limited. In this study, we evaluated risk factors associated with graft collapse. Methods We retrospectively reviewed 33 patients who underwent two level ACDF with anterior plating using allogenous bone graft from January 2013 to June 2017. Various factors related to cervical sagittal alignment were measured preoperatively (PRE), postoperatively (POST), and last follow-up. The collapse was defined as the ratio of decrement from POST disc height to follow-up disc height. We also defined significant collapses as disc heights that were decreased by 30% or more after surgery. The intraoperative distraction was defined as the ratio of increment from PRE disc height to POST disc height. Results The subsidence rate was 4.5% and graft collapse rate was 28.8%. The pseudarthrosis rate was 16.7% and there was no association between pseudarthrosis and graft collapse. Among the collapse-related risk factors, pre-operative segmental angle ( p =0.047) and intra-operative distraction ( p =0.003) were significantly related to allograft collapse. The cut-off value of intraoperative distraction ≥37.3% was significantly associated with collapse ( p =0.009; odds ratio, 4.622; 95% confidence interval, 1.470-14.531). The average time of events were as follows: collapse, 5.8±5.7 months; subsidence, 0.99±0.50 months; and instrument failure, 9.13±0.50 months. Conclusion We experienced a higher frequency rate of collapse than subsidence in ACDF using an allograft. Of the various preoperative factors, intra-operative distraction was the most predictable factor of the allograft collapse. This was especially true when the intraoperative distraction was more than 37%, in which case the occurrence of graft collapse increased 4.6 times. We also found that instrument failure occurs only after the allograft collapse.

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“…, end plate preparation 15) , cage type 1,7,22) , location 21) , cervical alignment 13,14) , and a small degree of segmental instability 10,12,19,25) . Furthermore, Lee et al 14) suggested that the main surgical and patient factors affecting subsidence are cervical alignment, age, and use of plates system.…”

Section: Discussionmentioning

confidence: 99%

“…The known risk factors for subsidence are age, body mass index (BMI), smoking history, low bone mineral density (BMD) 2) , end plate preparation 15) , cage type 1,7,22,26) , and location 21) . Furthermore, in a recent clinical study, cervical alignment 13,14) and even a small degree of segmental instability 10,12,19,25) have been suggested as risk factors for subsidence.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Bi-Cortical Screw Fixation for Subsidence and Cervical Alignment in Patients Undergoing Single-Level Anterior Cervical Discectomy and Fusion

Han

Moon

Kim

et al. 2019

Nerve

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Anterior cervical discectomy and fusion (ACDF) is a treatment for cervical degenerative disease. However, there are few in vivo or long-term data sets including complete graft consolidation. This study aimed to verify the validity of bi-cortical screw fixation in patients undergoing ACDF. Methods: We enrolled 133 patients who underwent ACDF between February 2002 and March 2017. Patients were divided into the mono-cortical fixation group (group A) and bi-cortical fixation group (group B). Consecutive cervical radiography was performed. The end point of data collection was completion of fusion. We evaluated graft subsidence, the global cervical angle (C2-C7 Cobb's angle), and segmental angle (SA; index level Cobb's angle). Results: There were no significant differences or surgical level between groups A and B (graft type p= 0.292, surgical level p=0.065). However, types of plate were statistically different (plate type p-value=0.011), and the difference in subsidence between groups A and B was significant (group A, 3.946±2.43 mm; group B, 2.369±1.96 mm, p<0.001). In the logistic regression, bi-cortical screw fixation was found to be the most important factor contributing to subsidence reduction (β-coefficient, 1.002; odds ratio=2.725; p=0.012). There was a significant difference in the SA when fusion was achieved (group A, 2.14±5.05°; group B, 4.84±4.83°; p=0.002). The change in the SA (ΔSA) was significantly different between group A and group B (group A, ΔSA-4.42±4.04°; group B, ΔSA-1.15±3.64°; p=0.001). Conclusion: Bi-cortical screw fixation in ACDF led to reduced graft subsidence and a less kyphotic SA change.

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A Lower T1 Slope as a Predictor of Subsidence in Anterior Cervical Discectomy and Fusion with Stand-Alone Cages

Cited by 15 publications

References 32 publications

Factors predicting loss of cervical lordosis following cervical laminoplasty: A critical review

Factors predicting loss of cervical lordosis following cervical laminoplasty: A critical review

Risk Factors of Allogenous Bone Graft Collapse in Two-Level Anterior Cervical Discectomy and Fusion

The Effect of Bi-Cortical Screw Fixation for Subsidence and Cervical Alignment in Patients Undergoing Single-Level Anterior Cervical Discectomy and Fusion

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