Neutral cervical sagittal vertical axis and cervical lordosis vary with T1 tilt

Hofler, Ryan C.; Muriuki, Muturi; Havey, Robert M.; Blank, Kenneth R.; Frazzetta, Joseph; Patwardhan, Avinash G.; Jones, Gary E.

doi:10.3171/2020.2.spine191363

Cited by 4 publications

(9 citation statements)

References 21 publications

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“…Most of the studies on cervical sagittal balance were clinical observational studies. Only one cadaveric experiment of Hofler et al (2020) reported that T1 tilt was Frontiers in Bioengineering and Biotechnology frontiersin.org closely associated with cervical SVA (CSVA) and lordosis, but their study did not examine the effect of T1 tilt change in ACF.…”

Section: Discussionmentioning

confidence: 99%

“…Most of the studies on cervical sagittal balance were clinical observational studies. Only one cadaveric experiment of Hofler et al (2020) reported that T1 tilt was closely associated with cervical SVA (CSVA) and lordosis, but their study did not examine the effect of T1 tilt change in ACF. Our study was in well agreement with Hofler et al (2020) , and our results indicated that ACF may bring slightly more influence to SVA than C2-C7 Cobb angle.…”

Section: Discussionmentioning

confidence: 99%

“…The validated C7–T1 FE model was then assembled with our previously developed C2-C7 FE model ( Liu et al, 2017a ; Liu et al, 2017b ) to construct the pre- and postoperative C2–T1 FE models. To acquire C2–T1 FE models with different T1 tilts, the pre- and postoperative FE models were applied ( Figure 1 ) with loading conditions similar to those in previous experimental tests ( Hofler et al, 2020 ). The superior part of the C2 vertebral body was constrained and only allowed for horizontal and vertical translation.…”

Section: Methodsmentioning

confidence: 99%

“…−10°, −5°, 0°, 5°, and 10°). The C2–C7 angle and sagittal vertical axis (SVA) were measured for each model when the model balance was reached under gravity loading, with the same method as described in ( Hofler et al, 2020 ) and displayed in ( Supplementary Figure SA1 ).…”

Section: Methodsmentioning

confidence: 99%

“…First described by Knott and others in 2010 ( Knott et al, 2010 ), T1 tilt is defined as the angle between the plane of the superior endplate of the T1 vertebral body and the horizontal plane. Clinical ( Iyer et al, 2016 ; Machino et al, 2016 ; Weng et al, 2016 ; Chen et al, 2017 ) and limited cadaveric ( Hofler et al, 2020 ) studies have demonstrated the close correlation of T1 tilt with cervical lordosis angles and foramen height; they also showed that T1 tilt may be associated with accelerated degeneration and symptoms in aging population, as well as with postoperative prognosis. Yet, its importance may be underestimated as T1 may not be clearly shown on routine radiographic examination of the cervical spine.…”

Section: Introductionmentioning

confidence: 99%

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Biomechanical influence of T1 tilt alteration on adjacent segments after anterior cervical fusion

Wei

Du²,

et al. 2022

Front. Bioeng. Biotechnol.

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Background: Anterior cervical fusion (ACF) has become a standard treatment approach to effectively alleviate symptoms in patients with cervical spondylotic myelopathy and radiculopathy. However, alteration of cervical sagittal alignment may accelerate degeneration at segments adjacent to the fusion and thereby compromise the surgical outcome. It remains unknown whether changes in T1 tilt, an important parameter of cervical sagittal alignment, may cause redistribution of biomechanical loading on adjacent segments after ACF surgery.Objective: The objective was to examine the effects of T1 tilt angles on biomechanical responses (i.e.range of motion (ROM) and intradiscal VonMises stress) of the cervical spine before and after ACF.Methods: C2–T1 FE models for pre- and postoperative C4–C6 fusion were constructed on the basis of our previous work. Varying T1 tilts of −10°, −5°, 0°, 5°, and 10° were modeled with an imposed flexion–extension rotation at the T1 inferior endplate for the C2–T1 models. The flexion–extension ROM and intradiscal VonMises stress of functional spinal units were compared between the pre- and postoperative C2–T1 FE models of different T1 tilts.Results: The spinal segments adjacent to ACF demonstrated higher ROM ratios after the operation regardless of T1 tilt. The segmental ROM ratio distribution was influenced as T1 tilt varied and loading conditions, which were more obvious during displacement-control loading of extension. Regardless of T1 tilt, intradiscal VonMises stress was greatly increased at the adjacent segments after the operation. As T1 tilt increased, intradiscal stress at C3–C4 decreased under 30° flexion and increased under 15° extension. The contrary trend was observed at the C6–C7 segment, where the intradiscal stress increased with the increasing T1 tilt under 30° flexion and decreased under 15° extension.Conclusion: T1 tilt change may change biomechanical loadings of cervical spine segments, especially of the adjacent segments after ACF. Extension may be more susceptible to T1 tilt change.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Biomechanical influence of T1 tilt alteration on adjacent segments after anterior cervical fusion

Wei

Du²,

et al. 2022

Front. Bioeng. Biotechnol.

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Relationship between C2 slope with sagittal parameters and clinical function of degenerative cervical kyphosis

Chai,

Yang,

et al. 2023

J Orthop Surg Res

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Purpose To explore the relationship between C2 slope with sagittal parameters and clinical function of degenerative cervical kyphosis (DCK). Methods A retrospective analysis of 127 patients with degenerative cervical spondylosis treated in our spinal deformity center from January 2019 to June 2022. Patients were categorized into two groups and compared based on C2-7 angle (C2-7 ≥ 5° as kyphosis group, C2-7 < 5° as lordosis group). Pearson correlation or Spearman correlation was used to analyze the relationship between C2S and conventional radiological parameters and health -related quality-of-life (HRQOL) outcomes as measured by the EuroQol 5 dimension questionnaire (EQ5D), NRS, and the neck disability index (NDI). The cutoff value of C2S was determined by a receiver operating characteristic (ROC) curve. Results There were 127 patients who met inclusion criteria (79 men and 48 women). Average 56.00 ± 10.27 years old (range 31–81 years old). C2S of kyphosis group is higher than non-kyphosis group. Aggravating cervical kyphosis increases cSVA positively. For all patients, C2S demonstrated a significant correlation with the O-C2 angle, C2-7 angle, cSVA, and TS-CL (p < 0.05). NRS, NDI and EQ5D-VAS scores revealed a significant correlation with C2S and cSVA (p < 0.01). For the subgroup of patients presenting with DCK, ROC curves demonstrated the cutoff values of C2S as 26.3°, and 30.5°, according to a cSVA of 40 mm, and severe disability expressed by NDI, respectively. Conclusion On the basis of retaining the consistency of cranio-cervical and cervico-thoracic structure, C2S can better analyze the sagittal alignment of DCK patients than TS-CL and has good practicability in clinical application and HRQOL evaluation.

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From the Spinopelvic Parameters to Global Alignment and Proportion Scores in Adult Spinal Deformity

Cho

Hyun

et al. 2023

Neurospine

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In the last 20 years, sagittal alignment and balance of the spine have become one of the most important issues in the field of spine surgery. Recent studies emphasize that sagittal balance and alignment are more important for health-related quality of life. The understanding of normal and abnormal sagittal alignment of the spine is necessary for the diagnosis and appropriate treatment of adult spinal deformity (ASD), and we will discuss the currently used classification of ASD, the parameters of sagittal alignment that are essential for the diagnosis of spinal deformity, compensatory actions to maintain sagittal balance, and the relationship between sagittal alignment and clinical symptoms. Furthermore, we will also discuss the recently introduced Global Alignment and Proportion scores. The Korean Spinal Deformity Society is publishing a series of review articles on spinal deformities to help spine surgeons better understand spinal deformities.

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Neutral cervical sagittal vertical axis and cervical lordosis vary with T1 tilt

Cited by 4 publications

References 21 publications

Biomechanical influence of T1 tilt alteration on adjacent segments after anterior cervical fusion

Biomechanical influence of T1 tilt alteration on adjacent segments after anterior cervical fusion

Relationship between C2 slope with sagittal parameters and clinical function of degenerative cervical kyphosis

From the Spinopelvic Parameters to Global Alignment and Proportion Scores in Adult Spinal Deformity

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