Evaluation of Pelvic Sacral Angle as an indicator for spinopelvic balance: A radiographic review of 56 individuals in standing and supine positions

doi:10.21203/rs.3.rs-3213201/v1

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Research Article

Evaluation of Pelvic Sacral Angle as an indicator for spinopelvic balance: A radiographic review of 56 individuals in standing and supine positions

https://doi.org/10.21203/rs.3.rs-3213201/v1

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Background

Over the past decade, the sagittal balance of the spine has garnered significant attention from surgeons. The compensatory mechanism of the pelvis plays a crucial role in maintaining the sagittal balance of the whole body. Several methods have been reported for reconstructing spinal sagittal balance based on pelvic parameters. However, controversy persists over restoring appropriate lumbar lordosis in spinal surgery. The purpose of this study is to investigate the role of PSA and APPA in assessing pelvic position and their correlation with spinopelvic parameters.

Methods

All patients underwent EOS and CT scans in both standing and supine positions to evaluate alterations in spinal sagittal balance parameters between the two postures. Measurements were taken for lumbar lordosis, thoracic kyphosis, sacral slope, pelvic incidence, pelvic tilt, pelvic sacral angle, and anterior pelvis plane angle. Changes and correlations in sagittal balance parameters in the spinal-pelvic region between the two postures were compared and analyzed.

Results

Statistically significant differences were found between the two groups for pelvic tilt (PT) (p < 0.05). The supine position showed a significantly higher mean value for pelvic sacral angle (PSA) (p = 0.005) compared to the standing position. Similarly, the supine position exhibited a significantly lower mean value for anterior pelvis plane angle (APPA) (p = 0.001) compared to the standing position. Strong correlations were observed between PSA and other spinopelvic parameters, particularly PT, pelvic inclination (PI), sacral slope (SS), thoracic kyphosis (TK), lumbar lordosis (LL), and APPA in both the supine and standing groups. Additionally, a strong correlation was found between APPA and pelvic parameters, especially PI.

Conclusion

The PSA and spinopelvic parameters showed a significant correlation. Our findings suggest that the PSA and APPA can be valuable parameters for assessing spinopelvic balance, particularly in cases involving pelvic rotation. Additionally, the spinal and pelvic parameters obtained in the supine position may offer greater reliability.

Pelvis Sacral Angle

Anterior Pelvis Plane Angle

Sacral slope

Lumbar lordosis

Whole-length Balance

Pelvis rotation

The spinal deformity is more than an aesthetic abnormality. Old compression vertebrae fracture or congenital kyphoscoliosis with abnormal vertebral body development and other diseases that invade the spine may cause severe thoracolumbar kyphotic deformity, often accompanied by intractable low back pain or compression of the spinal cord, leading to severe neurological symptoms or even paralysis [1, 2]. It is potentially fatal and degrades quality of life by inducing cardiac malfunction, spinal imbalance, and other disorders. Conservative treatment cannot relieve the symptoms or correct the deformities, surgical operation is usually needed. Given that the primary objectives of surgery are to prevent further deformity progression and restore the physiological alignment of the spine, orthopedic corrective procedures remain highly challenging [3]. The formulation of surgical strategies primarily relies on the correct and complete assessment evaluation spinal sagittal balance [4].

The sagittal equilibrium of spine is critical in maintaining trunk stability and posture. Sagittal imbalance will increase the energy consumption until it is difficult to maintain the upright position [5]. Pelvis region connecting the spine and lower extremities, plays an important role in the preservation of sagittal balance of the whole body [6]. Dubousset [7] introduced the concept of the 3-dimensional pelvic vertebra, implying that the pelvis functions as an additional caudal vertebra of the spine and emphasizing the need for simultaneous analysis of pelvic morphology during spine assessment. Some studies have emphasized the renovation of lumbopelvic balance in spine surgery, represented by the equation PI (pelvic incidence) = SS (sacral slope) + PT (pelvic tilt), as well as the spinopelvic compensatory mechanism, which includes pelvic retroversion, hip extension, and knee flexion [8]. Roussouly have proposed a physiological classification based on SS and PI, and it has been stated in the literature that the classification reduces the occurrence of postoperative problems [9–11].

The concept of PI-LL match [12], which reflects whether the lumbar curve is adapted to the morphology of the pelvis, is regulated by a negative feedback loop from the proximal thoracic kyphosis (TK) and a positive feedback loop from the distal pelvic tilt (PT). The adjustment of the PI-LL is achieved through the compensatory of both TK and PT [13]. Planning LL based on a constant PI has some limitations. The appropriate restoration of lumbar lordosis following spinal surgery remains a topic of considerable controversy. In previous study, the relationship between pelvic inclination (PI) and lumbar lordosis (LL) was investigated using PI as a measure of pelvic alignment [14]. However, the authors of that study assumed that PI and pelvic tilt were interchangeable, a viewpoint that we do not agree with.

Under physiological conditions, the apex of lumbar lordosis can be divided into upper and lower lumbar regions, with the lower region accounting for approximately two-thirds of the entire lumbar curve. Furthermore, the lower lumbar lordosis is precisely equal to SS [15], which is greatly influenced by changes in posture. Therefore, obtaining accurate anatomical value of SS can provide valuable information for preoperative planning, it can be challenging. Pelvic tilt [16] represents a compensatory mechanism that facilitates sagittal balance attainment in the context of diminished lumbar lordosis, with hip extension and knee flexion serving as the primary compensatory mechanisms. Nonetheless, PT or other parameters are seldom utilized to establish the standard position of the pelvis in the sagittal plane. With the clinical application of EOS system [17], it can be a reality to have a deeper understanding of the whole-body balance, thus, to realize the relation between spinopelvic region and the whole body.

The present study utilizes the pelvic sacral angle (PSA) as a functional indicator, defined as the angle between the horizontal line and the line connecting the front angle of the S1 endplate. Furthermore, the pelvic anterior plane angle (APPA) determines the angle between the pelvic anterior plane (APP) - a standard vertical line connecting the upper edge of the Pubic symphysis and the edge of the anterior superior iliac spine - representing pelvic pronation and retroversion. These two novel angles serve as valuable tools for evaluating pelvic sagittal plane positioning.

Patients may assume diverse positions during preoperative evaluation for photography, while literature reports reveal discrepancies in spinal balance parameters across various positions [18]. X-ray and CT imaging can obtain satisfactory sagittal parameters of the spine, CT scans have the advantage of being more clear and more reliable [19]. Although there is still controversy regarding whether sagittal parameters of the spine differ significantly in different body positions, we have observed changes in spinal-pelvic morphology, especially in the pelvic region, when patients shift from standing to supine position. Pelvic retroversion [20] can be compensatory for sagittal spinal imbalance. Thus, the pelvic spatial position and rotation are crucial to the equilibrium of spine. Our study puts forward a hypothesis to evaluate changes in pelvic position from two novel perspectives.

The objective of this study is to investigate the role of PSA and APPA in assessing pelvic position and their correlation with spinopelvic parameters.

Patient population

In this study, we conducted a review of 157 patients who received whole spine radiographs between January 2020 and December 2022. All patients underwent EOS and CT scans in both standing and supine positions to evaluate alterations in spinal sagittal balance parameters between the two postures.

The inclusion criteria of this study were as follows: 1. Participants aged between 27 and 69 years old; 2. Individuals with a body mass index (BMI) ranging from 17 to 29; 3. Volunteer to participate in this research.

The exclusion criteria included: 1. History of spine surgery or other spinal conditions; 2. Severe spinopelvic degeneration patients that made it difficult to recognize anatomical landmarks; 3. Personal or family history of malignancy spine trauma; 4. Inability to cooperate adequately and failure to complete the examination.

All patients underwent a standardized radiographic protocol, assuming a comfortable standing position with shoulders and elbows positioned in front of the body, while obtaining an EOS full body lateral radiograph from the skull to the feet, restricting pelvic coronal rotation. Additionally, CT scans were performed with patients in a neutral supine position, ensuring that their elbows and hands were positioned on the bars to prevent overlap of the upper extremities and spine.

This study finally included 56 patients (22 males and 34 females) who underwent whole spine radiographs. Informed consent was obtained from all individuals, and the study was approved by the ethics committee of our hospital.

Radiographic measurements

Measurements were performed by an independent spine surgeon using the PACS software. The detailed measurement methods are presented in Fig. 1.

Measurements included:

PI (pelvic incidence): angle formed by the line draw from midpoint of the upper sacral endplate to the center of femoral head and the line perpendicular to the upper sacral endplate.

PT (pelvic tilt): angle between the line through the midpoint of the sacral endplate to femoral heads axis and the vertical axis.

SS (sacral slope): angle between the sacral upper endplate and the horizontal line.

PSA (pelvic sacral angle): angle between the line drawn from the front point of sacral endplate to the superior margin of pubic symphysis and the horizontal line. To avoid name confusion, we used PSA instead of Pelvic Inclination in our study.

APPA (anterior pelvis plane angle): the angle between the anterior pelvic plane (APP), a standard vertical line, and the line connects the superior margin of pubic symphysis with margin of anterior superior iliac spine.

LL (lumbar lordosis): Cobb angle between the superior endplate of S1 and the upper endplate of L1 vertebral body.

TK (Thoracic kyphosis): Cobb angle between the upper endplate of T5 vertebral body and the lower endplate of T12 vertebral body.

Statistical analysis

The data were analyzed using Statistical Product and Service Solutions software (version26.0; SPSS, Chicago). Descriptive statistics are presented as mean (standard deviation [SD], range) or number(percentage) as appropriate. Student's t-test were used for the comparison of spinopelvic parameter values obtained in two positions. The association of spinopelvic parameters in each position group were investigated using Pearson correlation test. P < 0.05 was considered statistically significant.

Baseline information

A total of 56 patients with an average age of 50 years (ranging from 27 to 69 years old) were included in this study. Of these, 22 were male and 34 were female, accounting for 61% of the sample. Detailed information on height, weight, and BMI is described in Table 1.

Table 1

Baseline Demographics of all patients.
n = 56 patients
Age Mean (SD, range)	50	(14,27–69)
Sex, % Female	61%	(34/56)
Height Mean(SD, range)	1.65	(0.07, 1.5–1.78)
Weight Mean(SD, range)	66.85	(12.45,49–124)
Body Mass Index Mean(SD, range)	24.6	(4.34,17.71–48.43)

Difference of parameters under two positions

The supine and standing positions showed a statistically significant difference in several spinopelvic parameters, as described in Table 2. Specifically, the Pelvic Tilt (PT) was significantly lower in the supine position than in the standing position (t=-2.126, p = 0.036), while the Sacral Slope (SS) was significantly higher in the supine position than in the standing position (t = 2.011, p = 0.047). The Thoracic Kyphosis (TK) and Lumbar Lordosis (LL) were significantly lower in the supine position than in the standing position (t=-3.810, p = 0.000 and t=-2.211, p = 0.029, respectively).

Table 2

Spinopelvic parameters in standing and supine position group of all patients.
	Group (\(\stackrel{-}{x}\pm s\))		t	P
	supine position (n = 56)	standing position (n = 56)	t	P
PT	13.24 ± 5.74	15.95 ± 7.61	-2.126	0.036*
PI	45.08 ± 8.34	48.04 ± 10.17	-1.685	0.095
SS	31.93 ± 7.62	28.68 ± 9.38	2.011	0.047*
TK	15.37 ± 4.60	19.85 ± 7.50	-3.810	0.000**
LL	22.96 ± 7.39	26.44 ± 9.19	-2.211	0.029*
APPA	0.68 ± 1.48	4.07 ± 6.99	-3.555	0.001**
PSA	59.68 ± 1.86	56.33 ± 8.32	2.946	0.005**
P < 0.05 *P < 0.01

The Anterior Pelvis Plane Angle (APPA) was significantly lower in the supine position than in the standing position (t=-3.555, p = 0.001), while the Pelvic Sacral Angle (PSA) was significantly higher in the supine position than in the standing position (t = 2.946, p = 0.005). Our data shows that there is a smaller APPA in the supine position. The pelvic parameters measured in supine position may have smaller errors due to the pelvic in the upright position.

Relationship between PSA and spinopelvic parameters

As described in Table 3 and Table 4, pearson correlations were calculated for all parameters, and strong correlations were observed between PSA and other spinopelvic parameters in both supine and standing groups. Particularly with PT (R=-0.27 and R=-0.45, respectively), PI (R=-0.32 and R=-0.44, respectively), SS (R=-0.22), TK (R=-0.24), LL (R=-0.27), and APPA (R=-0.93 and R=-0.97, respectively). Figure 2a and Fig. 2b display the correlation between PI and PSA in two postures respectively.

Table 3

Pearson correlation test (group one: supine position)
	Mean	SD	PT	PI	SS	TK	LL	APP	PSA
PT	13.239	5.739	1
PI	45.077	8.340	0.309*	1
SS	31.932	7.619	-0.156	0.217	1
TK	15.371	4.598	0.328*	0.244	0.118	1
LL	22.957	7.395	-0.124	0.417**	0.600**	0.324*	1
APPA	0.677	1.478	0.229	0.235	0.192	0.245	0.254	1
PSA	59.684	1.863	-0.273*	-0.327*	-0.228	-0.246	-0.276*	-0.931**	1
P < 0.05 *P < 0.01

Table 4

Pearson correlation test (group two: standing position)
	Mean	SD	PT	PI	SS	TK	LL	APP	PSA
PT	15.946	7.609	1
PI	48.038	10.170	0.414**	1
SS	28.684	9.381	-0.401**	0.429**	1
TK	19.850	7.498	-0.026	0.041	0.054	1
LL	26.441	9.187	-0.167	0.513**	0.634**	0.261	1
APPA	4.070	6.987	0.423**	0.421**	0.177	-0.081	0.079	1
PSA	56.329	8.317	-0.446**	-0.435**	-0.171	0.079	-0.121	-0.966**	1
P < 0.05 *P < 0.01

Relationship between APPA and spinopelvic parameters

Additionally, there were strong correlations between APPA and pelvic parameters, particularly with PI (R = 0.42) and PT (R=-0.08). As presented in Fig. 2c, there is a strong correlation between PT and APPA in the standing position. The correlation between PT and APPA was illustrated in Fig. 2d.

Relationship between PSA and APPA

In the scatter plot (Fig. 3), A typical negative correlation between two parameters was observed: as APPA increases, PSA gradually decreases. We also observed a significant internal correlation between the two parameters: PSA = 60.7–1.13 * APPA (R2 = 0.933). When APPA is 0 °, PSA tends to concentrate at 60 °.

The sagittal alignment of the spine and pelvis plays a crucial role in maintaining body stability and support, ultimately affecting an individual's quality of life [21]. Since the introduction of the concept of pelvic incidence (PI) [22], its functional implications have been linked to various spinal pathologies, most notably spondylolisthesis. It is generally believed that PI is a fixed anatomical parameter that is not influenced by changes in body posture. This can be attributed to two reasons. Firstly, the centers of the acetabula, which are intrinsic radiographic landmarks of the pelvis, correspond to the centers of the bilateral femoral heads. Secondly, the upper endplate of the first sacral vertebra (S1) is connected to the pelvis via the sacroiliac joint, which allows for gliding movement and thus maintains relative stability. As a result, PI is widely regarded as an anatomical parameter [23].

The primary objective in deformity correction is to achieve a balanced spine with an appropriate alignment after osteotomies and fixations. Acquiring a more profound understanding of spinal balance is advantageous for devising surgical plans with enhanced efficacy and reduced complications. Current research on preoperative planning primarily involves surgical correction based on the values of parameters such as Pelvic Incidence (PI), Sacral Slope (SS), and Lumbar Lordosis (LL) [24–26]. The formation of lumbar lordosis and sacral slope is essential for our ability to stand upright. The sacral slope (SS) has a significant impact on the lumbar spine, not only owing to it directly affecting the position of lumbar lordosis and the apex of lordosis [27]. One validated system for categorization of ASD severity is the Scoliosis Research Society (SRS)–Schwab Classification System [28]. In the PI system, a mismatch between the Pelvic Incidence (PI) and Lumbar Lordosis (LL) greater than 11 degrees is associated with disability as measured by the Oswestry Disability Index (ODI), because patients with a PI-LL mismatch exceeding 11 degrees could experience pain while standing and walking.

A significant interrelation was noted among sagittal parameters of the spine, pelvis, and hip[29]. It is hypothesized that a fixed relationship exists between pelvic incidence (PI) and lumbar lordosis (LL), and maintaining their balance in daily activities necessitates the regulation of sacral slope (SS), indicating the inevitable involvement of the pelvis. Prior literature mainly focused on the compensatory impact of pelvic tilt (PT), with limited efforts to establish the standard pelvic position. However, the position of the pelvis significantly influences overall spinal alignment and even the overall body balance. Whether sagittal changes in lumbar region are due to degeneration or other causes, a mismatch between Pelvic Incidence (PI) and Lumbar Lordosis (LL) can have an impact on both local and global sagittal balance. Surgical intervention does not directly alter Pelvic Tilt (PT). Instead, when Lumbar Lordosis (LL) is harmonized with Pelvic Incidence (PI), the compensatory mechanism becomes unnecessary and PT improves as the hip reverts from terminal extension and the pelvis rotates forward. However, it is challenging to predict the extent to which PT will change following surgery. Sacral Slope (SS) is dependent on the position of the pelvis and is inversely correlated with Pelvic Tilt (PT). Lumbar Lordosis (LL) is the sagittal parameter most amenable to surgical correction. Diebo BG et al [30] believes that the primary goal of adult spinal deformity surgery is often to reduce the mismatch between Pelvic Incidence (PI) and LL to less than 11 degrees. Therefore, when planning a deformity correction surgery, it is important for spine surgeons to evaluate patients’ standing lateral flexion/extension and supine radiographs. In a randomized and prospective study involving 50 healthy and asymptomatic individuals, Place HM et al. [31] presented evidence that challenges the conventional view of pelvic incidence (PI) as a fixed parameter. Their findings indicate the presence of functional motion at the sacroiliac joint and reveal that PI varied with changes in pelvic position among a significant proportion of subjects. These results lend support to the idea that deliberate changes in posture may lead to alterations in PI.

Traditionally, pelvic incidence (PI) and other spinopelvic sagittal parameters have been measured using X-rays taken with the patient standing. However, obtaining a clear sagittal view of the sacral endplate and superimposition of both femoral heads can be challenging. Pelvic rotation may also cause inaccurate sacral endplate localization. Recent studies have shown that magnetic resonance imaging (MRI) and CT are more reliable tools for evaluating certain spinal sagittal parameters [32]. And researchers such as Jentzsch et al [33]. and Lee et al [34] have used CT scans to accurately determine spinal sagittal balance values. Vrtovec et al [35] developed a computerized method for measuring PI and found that there were significant differences between PI values measured using CT and those measured using X-ray imaging, which means spinopelvic parameters changed significantly with the change of body position from standing to supine. In our study, no distinct varied finding about PI values vary between standing and supine positions of the same individual were detected, but we find SS, LL, TK, PT, APPA and PSA changed significantly with the change of body position.

Obtaining an accurate value for pelvic parameters can be a challenging task. Another possible explanation for this discrepancy is the presence of pelvic rotation, especially pelvic retroversion [36]. The spinopelvic connection is dynamic, as subjects can easily learn to rotate their pelvis anteriorly or posteriorly on the femoral head while maintaining an erect posture. Therefore, to truly understand the influence of the pelvis on the spinal column, it is necessary to examine spinopelvic parameters in standardized pelvic positions. In cases where malalignment recurs, anterior pelvic rotation and pelvic retroversion may exacerbate moments across the sacroiliac joints. This can result in ligament laxity and an increase in pelvic incidence. The findings of Hayden AM et al [37] demonstrate that it is possible to intentionally alter the position of the pelvis and adjacent spinal column in space. Understanding this relationship is crucial for comprehending sagittal balance and may influence the treatment approach for patients with spinal deformities. Lee KY et al [38] conducted an evaluation to determine whether actual pelvic incidence (PI) measurements are affected by the rotation of the pelvis. Their findings suggest that PI may deviate from their true anatomical values and that computed tomography (CT) or magnetic resonance imaging (MRI) may provide more accurate methods for defining pelvic parameters. Jin HM et al [39] investigated the influence of pelvic rotation on the PI, PT, and SS, suggesting that Pelvic incidence (PI) may vary in response to pelvic rotation. To ensure reliable measurements of PI, pelvic tilt (PT), and sacral slope (SS), the angle of rotation must not exceed 17.5 degrees. In order to obtain accurate and reliable spinopelvic parameters and eliminate the effects of body position and measurement of bilateral femoral heads, Suzuki H et al [40, 41] proposed the use of anatomical sacral slope (a-SS), a pelvic anatomical parameter that does not require the use of the center of the femoral head. It has been shown to strongly correlate with pelvic incidence (PI) during three-dimensional measurements.

With the application of full-length radiography technologies, such as EOS, researchers have recognized the impact of the lower limbs on the pelvis and spine. The pelvis serves as a bridge between the trunk and lower limbs, transmitting mechanical forces through the sacroiliac and hip joints. As such, joint movement of lower extremities can induce pelvic position. However, there exists poor evidence over which demographic features contribute to the development of spinal disorders. The human pelvis is composed of the ilium, ischium, and pubis bones and has a complex and irregular shape, which can make imaging measurements challenging.

To determine whether the pelvis is in a balanced position, some scholars have proposed the pelvic inclination (PI). The angle which the plane of the pelvic inlet makes with the horizontal plane when the patient is standing. To further refine this measurement in the evaluation of sagittal balance, PSA, the angle formed between the line connecting the midpoint of the femoral head and the midpoint of the upper endplate of the sacrum and the horizontal line, was purposed to detect the orientation of pelvis.

PSA is relatively a new angle for evaluating whether the pelvis is in a neutral (balanced) position, because its first intense was to assess the delivery pathway in the birth giving. The degree of pelvic sacral angle stated by Imai N is also nearly usually 60° [42]. Unlike PI or spinal parameters, we found it can reflect whether the pelvis is in a neutral or balanced state, which is a physiological status where the energy consumption of muscles, joints, and ligaments is minimal. When the pelvis is in a neutral position, the actual or anatomical values of SS, PI, and PT can be obtained as a basis for physiological classification or the surgical restoration of spinal alignment. Whether the treatment outcome is better remains to be further verified by mechanics and further clinical practice.

What interests most is that the relation between PSA and APPA. It is hard to acquire actual value of SS in standing position, where pelvic retroversion usually occurs. We measured APPA and PSA in lateral views, as well as other spinal and pelvic parameters, on radiographs of 56 patients when they were in standing and supine position respectively. We noticed that a relatively fixed relationship: 60 = APPA + PSA. The compensation of the spine and lower limbs to the pelvis diminishes in the supine position, and the angle APPA between the front plane of the pelvis and the pelvis is primarily 0 degrees. PSA values are more concentrated at approximately 60 ° This phenomenon, in our study, did not occur by chance. However, the pelvic retroversion occurs in the standing position, and the APPA angle that occurs at this moment is noted as a positive value. At this point, a PSA that is different from and typically lower than the value of the supine posture can be measured. Based on this, we hypothesize that the development of pelvic tilt anteriorly, the pelvis crossing the APP forward, and the increase in PSA may take place. Unfortunately, we failed to include patients with standing anteverted pelvis in our study.

We suggest that the balance parameters, particularly SS, should be carefully referenced to when planning surgery based on the differences in PSA and APPA in various body positions. This can provide theoretical guidance for the reconstruction of the spinal sagittal plane, thereby improving clinical treatment outcomes. Reference to the spine and pelvis parameters in the supine position, a balance state, may obtain better curative effect. Nevertheless, extensive therapeutic and biomechanical examination is essential for verifying the concrete results.

Although the findings of this current study in patients with spinal disorders cannot be directly generate a formula for reconstructing spinal balance, we have found a framework to evaluate and limit pelvic parameters. we noticed that when a subject changes from the standard upright position to the natural and comfortable standing position, the overall degree of kyphosis in the spine becomes larger, consistent with the changes that occur due to aging. By comparing the two postures, we found that in supine position, the pelvis tends to have a more balanced shape, but this result requires a larger sample size and validation in different age and ethnic groups. There are differences in pelvic morphology between different genders, and there are certain shortcomings in this study. Given the necessity for volunteers to undergo imaging examinations in both positions simultaneously, the sample size in this study is limited, and the participants are predominantly young, which could introduce bias. Subsequent investigations will encompass a larger and more diverse cohort to facilitate large-scale or multicenter research. While pelvic sacral angle (PSA) holds significance in assessing pelvic position, its clinical decision-making implications remain insufficient. Additional examination of pelvic compensation is warranted to enhance clinical applicability.

Acknowledgments

Not applicable in this section.

Author contributions

Hao Qi: Data analysis, Writing – original draft, performed the experiments, Writing – review & editing. Rui Xue: Tables and Figures Preparation. Xiangnan Tian: Data analysis, Writing – original draft. Feiyu Zu: Provided technical support for experiments. Zhiyong Hou: Figures and Tables preparation, performed the experiments. Wei chen: Provided technical support for experiments. Xianzhong Meng: Data analysis, performed the experiments. Di Zhang: Supervision, Project administration, Funding acquisition, Writing – review & editing.

Funding

This study is supported by the China National Natural Science Foundation (82072454).

Availability of data and materials

The data that support the findings of the current study are available from the corresponding author upon reasonable request.

All methods were conducted in accordance with applicable guidelines and regulations.

Ethics approval and consent to participate

Ethical approval and consent to participate This study was approved by the ethics committee of the Third Hospital of Hebei Medical University. Informed consent was obtained from all subjects and/or their legal guardian(s).

Consent for publication

Not applicable.

Competing interest

The authors declare that they have no competing interests.

Author details

¹ Department of Spine Surgery, The Third Hospital of Hebei Medical University, Shijiazhuang 050051, China.

²CT/MRI Department of the Third Hospital of Hebei Medical University, Shijiazhuang 050051, China

³Key Laboratory of Biomechanics of Hebei Province, Shijiazhuang 050051, China

⁴Department of Orthopaedic Surgery, the Third Hospital of Hebei Medical University, Shijiazhuang 050051, China

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Evaluation of Pelvic Sacral Angle as an indicator for spinopelvic balance: A radiographic review of 56 individuals in standing and supine positions

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Abstract

Background

Methods

Results

Conclusion

Figures

Background

Methods

Patient population

Radiographic measurements

Statistical analysis

Results

Baseline information

Difference of parameters under two positions

Relationship between PSA and spinopelvic parameters

Relationship between APPA and spinopelvic parameters

Relationship between PSA and APPA

Discussion

Conclusion

Declarations

References

Additional Declarations

Status:

Version 1