Spinal alignment shift between supine and prone CT imaging occurs frequently and regardless of the anatomic region, risk factors, or pathology

AbstractComputer-assisted spine surgery based on preoperative CT imaging may be hampered by sagittal alignment shifts due to an intraoperative switch from supine to prone. In the present study, we systematically analyzed the occurrence and pattern of sagittal spinal alignment shift between corresponding preoperative (supine) and intraoperative (prone) CT imaging in patients that underwent navigated posterior instrumentation between 2014 and 2017. Sagittal alignment across the levels of instrumentation was determined according to the C2 fracture gap (C2-F) and C2 translation (C2-T) in odontoid type 2 fractures, next to the modified Cobb angle (CA), plumbline (PL), and translation (T) in subaxial pathologies. One-hundred and twenty-one patients (C1/C2: n = 17; C3-S1: n = 104) with degenerative (39/121; 32%), oncologic (35/121; 29%), traumatic (34/121; 28%), or infectious (13/121; 11%) pathologies were identified. In the subaxial spine, significant shift occurred in 104/104 (100%) cases (CA: *p = .044; T: *p = .021) compared to only 10/17 (59%) cases that exhibited shift at the C1/C2 level (C2-F: **p = .002; C2-T: *p < .016). The degree of shift was not affected by the anatomic region or pathology but significantly greater in cases with an instrumentation length > 5 segments (“∆PL > 5 segments”: 4.5 ± 1.8 mm; “∆PL ≤ 5 segments”: 2 ± 0.6 mm; *p = .013) or in revision surgery with pre-existing instrumentation (“∆PL presence”: 5 ± 2.6 mm; “∆PL absence”: 2.4 ± 0.7 mm; **p = .007). Interestingly, typical morphological instability risk factors did not influence the degree of shift. In conclusion, intraoperative spinal alignment shift due to a change in patient position should be considered as a cause for inaccuracy during computer-assisted spine surgery and when correcting spinal alignment according to parameters that were planned in other patient positions.

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Cervical sagittal alignment in patients with dropped head syndrome

Journal of Orthopaedic Surgery ◽

10.1177/2309499021990112 ◽

2021 ◽

Vol 29 (1) ◽

pp. 230949902199011

Author(s):

Weiqing Qian ◽

Kenji Endo ◽

Takato Aihara ◽

Yasunobu Sawaji ◽

Hidekazu Suzuki ◽

...

Keyword(s):

Cervical Spondylosis ◽

Sagittal Alignment ◽

Vertical Axis ◽

Spinal Alignment ◽

Sagittal Vertical Axis ◽

Dropped Head Syndrome ◽

Sagittal Spinal Alignment ◽

Cervical Sagittal Alignment ◽

Lumbar Alignment ◽

The Relationship

Background: Dropped head syndrome (DHS) can be divided into two types, the positive sagittal vertical axis (SVA) type and the negative SVA type. However, the cervical sagittal alignment of DHS including global sagittal spinal alignment and the typical cervical alignment of the types of DHS is still unclear. The purpose of this study was to clarify the character of cervical sagittal alignment of DHS and analyze the relationship between cervical sagittal alignment and global sagittal spinal alignment. Methods: The subjects were 35 DHS patients (10 men, 25 women, mean 71.1 years old). They were divided into two groups: negative DHS (N-DHS group, SVA < 0 mm) and positive DHS group (P-DHS group, SVA ≥ 0 mm). As control, 28 age-matched cervical spondylosis patients (CS, 21 men, 7 women, mean 67.4 years old) were analyzed. The following parameters were measured on lateral global-spine standing radiographs: cervical SVA (C2-C7SVA), O-C2A (O-C2 angle), C2 slope (C2S), C2-7A (C2-7 angle), T1 slope (T1S) and C7SVA. Results: The results of measurements of each of the averaged sagittal alignment parameters were (CS, P-DHS, N-DHS): C2-7SVA(26.2 mm, 47.3 mm, 44.5 mm), O-C2 angle (35.0°, 37.1°, 39.3°), C2S (16.5°, 31.4°, 33.8°), C2-7A (9.3°, 9.9°, −16.6°), T1S (22.9°, 39.7°, 25.7°), C7SVA (35.3 mm, 51.0 mm, −43.1 mm). C2-C7SVA and C2S were significantly larger in both types of DHS compared to CS. Comparing P-DHS with N-DHS, C2-C7A and T1S were significantly smaller in N-DHS. Conclusions: O-C2A did not differ significantly among CS, P-DHS and N-DHS. In DHS patients, C2-7SVA and C2S were significantly larger than those of CS regardless of the type of DHS. The typical cervical sagittal alignment of DHS was different between P-DHS and N-DHS. In P-DHS, C2-7A and T1S were larger than those in N-DHS and the imbalance of thoraco-lumbar alignment should be noted.

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Novel Method for Evaluation of Sagittal Spinal Alignment Using Cluster Analysis of Slope of Each Vertebra.

10.21203/rs.3.rs-1111502/v1 ◽

2021 ◽

Author(s):

Yoshitaka Matsubayashi ◽

Yasushi Oshima ◽

Yuki Taniguchi ◽

Toru Doi ◽

So Kato ◽

...

Keyword(s):

Cluster Analysis ◽

Sagittal Alignment ◽

Thoracolumbar Junction ◽

Sacral Slope ◽

Spinal Alignment ◽

Sagittal Spinal Alignment ◽

Significant Difference ◽

Novel Method ◽

And Cluster Analysis ◽

Whole Spine

Abstract Background: The parameters of sagittal spinal alignment proposed to date measure only the specific sectional angle or the specific sectional distance of the entire spine. To evaluate the alignment of the entire spine without segmentation, we sought to measure and analyze the slope of each vertebral body from skull to pelvis. The purpose of this study was to confirm the effectiveness of this novel analytic method for the evaluation of spinal alignment that considers the slope of each spinal vertebra using graph and cluster analysis.Methods: Every spinal slope from McGregor’s slope to the sacral slope of 88 patients who underwent standing whole spine radiography was measured. Subsequently, we conducted cluster analysis of each spinal slope to understand the characteristics of sagittal alignment.Results: Cluster analysis of whole spinal slopes did not provide useful results in this study because the number of cases per cluster was small due to the large number of parameters. Therefore, we focused the cluster analysis on only the cervical spine slopes. Then, we categorized cervical alignment into four groups (named Normal, Mismatch, Straight, and Sigmoid) based on the results of the cluster analysis. Patients in the Normal and Mismatch groups were older and had lower lumbar apex (L4), apparent lordo-kyphosis around the thoracolumbar junction, and high thoracic kyphosis (TK). Patients in the straight and sigmoid groups were younger, had a higher lumbar apex (L3), flat thoracolumbar junction, and low TK. There was no significant difference between the four groups with respect to pelvic incidence (PI) or pelvic tilt (PT).Conclusion: We proposed a novel method for visually understanding sagittal alignment. Using this analysis method, differences and similarities of sagittal alignment between each group can be easily identified. More detailed analysis of the whole spine may be possible by increasing the number of cases.

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Variation in Sagittal Alignment Parameters in Adult Patients before Spine Surgery: A Serial Imaging Study Using Antero-Posterior and Latero-Lateral Projections

Diagnostics ◽

10.3390/diagnostics11112141 ◽

2021 ◽

Vol 11 (11) ◽

pp. 2141

Author(s):

Hunjong Lim ◽

Eugene Lee ◽

Joon-Woo Lee ◽

Bo-Ram Kim ◽

Yusuhn Kang ◽

...

Keyword(s):

Spine Surgery ◽

Subgroup Analysis ◽

Adult Patients ◽

Rank Test ◽

Time Interval ◽

Spinal Alignment ◽

Sagittal Vertical Axis ◽

Eos Imaging ◽

Sagittal Spinal Alignment ◽

Sagittal Parameters

Sagittal parameters of the spine are closely related to the evaluation and treatment of spine disease. However, there has been little research on variations in preoperative sagittal spinal alignment. This study was conducted to assess the variation in sagittal spinal alignment on serial antero-posterior and latero-lateral projections (EOS imaging) in adult patients before spine surgery. The sagittal parameters of 66 patients were collected from two serial images. Comparison between the first and second sagittal parameters was evaluated using the Wilcoxon signed-rank test. Subgroup analysis was performed based on the time interval between radiographs, patient’s age, and type of surgery. The sagittal vertical axis (SVA) exhibited statistically significant changes (p = 0.023), with the mean SVA increasing statistically (61.7 mm vs. 73.6 mm) and standard deviation increasing (51.5 mm vs. 61.6 mm) in the second image. Subgroup analysis showed significant differences in SVA (p = 0.034) in patients with an interval of >3 months; statistical differences in borderline levels in the SVA (p = 0.049) were observed in patients aged >65 years. Other parameters did not show statistically significant differences, except for SVA. Furthermore, SVA differences were statistically significant with increases in the EOS interval (>3 months) and patient age (>65 years).

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