Observational Study of Sacral Nerve Function After Sacral Tumor Resection
Conditions: Sacral Tumors
Sponsor: Shanghai Changzheng Hospital

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
Study Protocol 
Observational Study of Sacral Nerve Function After Sacral Tumor Resection 
Background 
Sacral tumors represent a rare subset of spinal neoplasms, accounting for only 1–7% of 
all spinal tumors. Among them, primary sacral tumors—such as chordoma and 
chondrosarcoma—are particularly uncommon. Due to their poor responsiveness to 
radiotherapy and chemotherapy, en bloc surgical resection remains the mainstay of 
treatment. However, early diagnosis is often difficult owing to their insidious onset, 
nonspecific symptoms, and limited detectability via routine musculoskeletal examinations. 
For patients with primary malignant tumors of the sacrum, complete surgical excision is 
essential for achieving long-term tumor control and potential cure. Nevertheless, sacral 
resection is technically demanding. The anatomical complexity of the sacral region, proximity 
to critical neurovascular and visceral structures, and the frequent involvement of the presacral 
space or sacral canal contribute to a high risk of intraoperative complications, including 
massive hemorrhage and soft tissue defects. Multidisciplinary collaboration, especially with 
reconstructive surgeons, is frequently required to ensure adequate wound closure and 
functional restoration. Achieving negative surgical margins is critical for minimizing local 
recurrence. 
To achieve complete tumor removal, surgeons may need to sacrifice sacral nerve roots, 
which can significantly compromise postoperative neurological function. Prior studies have 
demonstrated that preservation of bilateral S2 roots maintains normal gait in 56.2% of 
patients, while bilateral S3 root preservation increases this to 94.1%. With low-level sacral 
resections that spare nerve roots, all patients have been reported to retain normal ambulation. 
In contrast, bilateral S2 root sacrifice almost universally results in bowel and bladder 
dysfunction. Even unilateral S2 root preservation yields only 25% normal bladder function, 
which increases to 39.9% with bilateral preservation. Similarly, preservation of one or both 
S3 roots leads to 72.7% and 83.3% normal bladder function, respectively. For bowel function, 
bilateral S3 preservation is associated with 94% normal function, while single S3 root 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
preservation results in dysfunction in over 70% of cases. Notably, preservation of a single S4 
root has been sufficient to maintain normal bowel and bladder function in 100% of patients. 
Motor outcomes are largely determined by S1 root involvement. 
Thus, sacral nerve root sacrifice may result in profound motor, urinary, and bowel 
deficits, substantially affecting quality of life. However, failure to achieve complete resection 
may lead to local recurrence and eventual deterioration of the same functions. Therefore, 
optimizing the balance between radical resection and functional preservation remains a 
central challenge in sacral tumor surgery. 
Despite the recognized importance of nerve root preservation, current literature on 
functional outcomes is limited by retrospective design, small sample sizes, and non-
standardized outcome metrics, often using binary descriptors such as “normal” or 
“abnormal.” While some anatomical classifications—such as the use of the S2/3 disc as a 
surgical landmark—have been proposed, they primarily serve biomechanical or 
reconstructive purposes and lack correlation with functional outcomes. No prospective study 
has yet established a reliable, predictive model for post-surgical bladder and bowel function 
based on resection level or nerve root status. 
This study therefore aims to address these limitations by conducting a prospective 
observational cohort study to evaluate postoperative neurological function—particularly 
motor, bladder, and bowel outcomes—following sacral tumor resection. The findings are 
expected to provide high-quality evidence to support surgical decision-making and improve 
individualized treatment planning for patients with sacral tumors. 
Objectives 
The primary objective of this study is to prospectively evaluate the functional outcomes 
following sacral tumor resection, with a specific focus on postoperative motor function, 
bowel function, and bladder function. By conducting systematic follow-up assessments, this 
study aims to investigate the key factors influencing neurological recovery and functional 
prognosis in patients undergoing sacral surgery. 
A particular emphasis is placed on analyzing the relationship between postoperative 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
functional status and intraoperative variables, including the level of sacral osteotomy and the 
extent of sacral nerve root sacrifice. Additionally, the study seeks to document changes in 
neurological function and health-related quality of life over time using validated clinical 
instruments. 
Ultimately, this single-center prospective study is designed to generate high-quality 
clinical evidence regarding the determinants of postoperative neurological outcomes. The 
findings are expected to inform surgical decision-making, facilitate the development of more 
precise operative strategies, and support the implementation of individualized treatment 
planning for patients with sacral tumors. 
Study Design and Overview 
1.Overall Study Design and Plan 
This is a single-center prospective observational study conducted in patients 
diagnosed with sacral tumors. The study includes the following phases: 
Patient screening and eligibility confirmation, based on clinical diagnosis of sacral 
tumors. Sample size was determined according to retrospective data and statistical power 
calculations. 
Enrollment of eligible patients based on predefined inclusion and exclusion criteria, 
followed by informed consent. 
Comprehensive data collection at multiple time points, including preoperative, 
intraoperative, and postoperative variables. 
Follow-up assessments to monitor functional outcomes and complications. 
Data quality control and statistical analysis of the results. 
2. Study Population 
The study population includes patients with a confirmed diagnosis of sacral tumor 
who are scheduled to undergo or have recently undergone surgical resection. 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
2.1 Inclusion Criteria 
• Age between 12 and 80 years. 
• Pathologically confirmed diagnosis of a primary sacral tumor or metastatic 
tumor from other solid malignancies. 
• Ability to understand the study and provision of written informed consent. 
2.2 Exclusion Criteria 
• Poor general condition deemed unfit for surgery. 
• Pre-existing diseases or surgical history affecting bowel or bladder function. 
• Missing data on intraoperative resection level or sacral nerve root 
management. 
• Pregnancy or lactation. 
• Incomplete follow-up or loss to follow-up. 
2.3 Withdrawal Criteria 
Patients may voluntarily withdraw from the study at any time, in accordance with ethical 
standards. 
3 Sample Size and Grouping 
Based on previous research and the primary endpoint (bowel function score at 12 
months), the outcome is treated as a continuous variable. Sample size (N) was calculated 
using the following parameters: 
• Significance level (α) = 0.05 → Z<sub>α/2</sub> = 1.96 
• Power (1−β) = 0.80 → Z<sub>β</sub> = 0.84 
• Standard deviation (σ): derived from prior data 
• Expected effect size (d): minimal clinically significant difference 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
No interventional grouping will be used; analysis will be based on stratification by 
resection level and nerve preservation. 
4 Study Procedures and Data Collection 
(1) Preoperative Assessment 
Patients undergo full clinical evaluation, including history-taking, physical examination, and 
imaging studies. After eligibility is confirmed and informed consent is signed, the following 
baseline data are collected: 
Demographics and clinical characteristics: sex, age, BMI, prior treatments, surgical 
history 
Motor function: Frankel grading system 
Bowel function: Cleveland Constipation Score, Wexner Incontinence Score, anorectal 
manometry, rectal filling test 
Urinary function: ICIQ-SF, Saito classification, uroflowmetry (Qmax, total volume, 
voiding time), urodynamics (bladder capacity, pressure, flow), post-void residual, 
compliance, bladder wall thickness 
Pain: Visual Analog Scale (VAS) 
Quality of life: QLQ-C30 questionnaire 
Other: use of preoperative embolization or balloon occlusion 
(2) Intraoperative Data Collection: Operative duration and blood loss, Transfusion 
requirement, Surgical approach and instrumentation, Level of sacral osteotomy, Sacral nerve 
root ligation or sacrifice, Tumor resection technique, Intraoperative bowel and neurovascular 
involvement or adhesions, Pelvic floor reconstruction, Intraoperative complications 
(3) Postoperative Follow-Up and Evaluation:Follow-up assessments will be conducted 
at 2 weeks, 3 months, 6 months, and 12 months postoperatively. The following evaluations 
will be performed: 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
Motor function: Frankel score 
Bowel function: Cleveland and Wexner scores, rectal pressure and filling tests 
Urinary function: ICIQ-SF, Saito grading, uroflowmetry, urodynamics, bladder 
assessments 
Pain: VAS (recorded as worst pain of the day), NSAID usage standardized; opioid use 
and corresponding VAS recorded 
Quality of life: QLQ-C30 
Complications: including thrombosis, surgical site infection, delayed wound healing, 
CSF leak, hemorrhage, pulmonary/urinary infections 
Psychosocial and economic impact 
Disease control: PFS and OS assessed via imaging (MRI) and symptom evaluation 
Adjuvant therapy: regimen, dosage, duration, and adverse effects 
(4) Statistical Analysis 
All data will be analyzed using SPSS software. Continuous variables will be expressed as 
mean ± standard deviation and compared using t-tests. Statistical significance is defined as p 
< 0.05. 
Sample Size Calculation and Statistical Analysis 
Sample Size Estimation 
The primary outcome of this study is the bladder function score at 12 months 
postoperatively, treated as a continuous variable. Sample size was calculated based 
on the following assumptions: 
Significance level (α): 0.05 
Power (1−β): 80% 
Estimated standard deviation (σ): 0.94, based on previously published data on 
bladder function scores following sacral tumor resection 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
Minimum detectable effect size (d): 0.3, representing a clinically meaningful 
difference in functional outcome 
Using the standard formula for comparing two means:77
 
Considering a 10% attrition rate, the adjusted sample size is:86 
Given that the study will include 8–10 independent variables for multivariate 
modeling, the sample size was also estimated using the rule-of-thumb for linear 
regression analysis, requiring 10–15 subjects per predictor variable, resulting in a 
minimum sample size of 80–150. 
In addition, using the power analysis formula for linear regression based on the 
expected coefficient of determination (R²), the effect size f² is defined as: 
 
Assuming a small-to-moderate effect size and 10 predictors, a minimum of 45 
subjects per predictor is needed. To ensure statistical power and account for 
potential dropouts, the final target sample size is set at 400 participants. 
Statistical Analysis Plan 
All data will be analyzed using SPSS version. The analysis plan is as follows: 
Descriptive statistics will be presented as means ± standard deviations for 
continuous variables and counts with percentages for categorical variables. 
Univariate analysis will compare functional outcomes (e.g., bladder and bowel 
scores, motor function) between subgroups using independent t-tests, chi-square 
tests, or Mann–Whitney U tests, depending on data distribution. 
Multivariate linear regression will be used to assess the association between 
surgical factors (e.g., resection level, nerve root sacrifice) and functional outcomes, 
controlling for covariates.Repeated measures ANOVA or linear mixed models may 
be used to assess longitudinal changes in functional scores over time.Survival 
outcomes such as progression-free survival (PFS) and overall survival (OS) will be 
estimated using Kaplan–Meier methods and compared using the log-rank test.A 
two-sided p-value < 0.05 will be considered statistically significant. 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
References: 
[1] 
Feldenzer J, McGauley J, McGillicuddy J. Sacral and presacral tu-mors: problems 
in diagnosis and management. Neurosurgery 1989;25:884–91. 
[2] 
FOURNEY DR, RHINES LD, HENTSCHEL SJ, et al. En bloc resection of 
primary sacral tumors: classification of surgical approaches and outcome[J]. 
Journal of Neurosurgery: Spine, 2005, 3(2): 111-22. 
[3] 
Todd LT Jr, Yaszemski MJ, Currier BL, Fuchs B, Kim CW, Sim FH. Bowel and 
bladder function after major sacral resection. Clin Orthop Relat Res. 
2002;(397):36-39. 
[4] 
Chen K, Yang H, Lu J, Liu J, Chen X. Prognostic factors of sacral chordoma after 
surgical therapy: a study of 36 patients. Spinal Cord 2010;48:166–71. 
[5] 
Zoccali C, Skoch J, Patel AS, Walter CM, Maykowski P, Baaj AA. Residual 
neurological function after sacral root resection during en-bloc sacrectomy: a 
systematic review. Eur Spine J. 2016;25(12):3925-3931. 
[6] 
Fourney DR, Rhines LD, Hentschel SJ, et al. En bloc resection of primary sacral 
tumors: classification of surgical approaches and outcome. J Neurosurg Spine. 
2005;3(2):111-122. 
[7] 
Moran D, Zadnik PL, Taylor T, et al. Maintenance of bowel, bladder, and motor 
functions after sacrectomy. Spine J. 2015;15(2):222-229. 
[8] 
Ji T, Guo W, Yang R, Tang X, Wang Y, Huang L. What Are the Conditional 
Survival and Functional Outcomes After Surgical Treatment of 115 Patients With 
Sacral Chordoma?. Clin Orthop Relat Res. 2017;475(3):620-630. 
[9] 
Yu B, Zheng Z, Zhuang X, et al. Biomechanical effects of transverse partial 
sacrectomy on the sacroiliac joints: an in vitro human cadaveric investigation of 
the borderline of sacroiliac joint instability. Spine (Phila Pa 1976). 
2009;34(13):1370-1375. 
[10] 
Bederman SS, Shah KN, Hassan JM, Hoang BH, Kiester PD, Bhatia NN. Surgical 
techniques for spinopelvic reconstruction following total sacrectomy: a systematic 
review. Eur Spine J. 2014;23(2):305-319. 
 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
Informed Consent Form – Participant Information Sheet 
Dear Mr./Ms. __________, 
We sincerely invite you to participate in the clinical study titled “Observational 
Study on Sacral Nerve Function Following Sacral Tumor Resection”, conducted 
by the Department of ________. 
Before you decide whether to participate, please carefully read this consent form. 
It contains information about the study’s background, purpose, procedures, potential 
benefits and risks, and the protection of your rights. This document is designed to help 
you make an informed decision about your participation. If you have any questions, 
please do not hesitate to consult with the investigators. If you agree to participate, 
please sign this consent form and retain a copy for your records. This study protocol 
has been reviewed and approved by the Ethics Committee of Shanghai Changzheng 
Hospital. 
1. Why is this study being conducted? 
With advancements in surgical techniques and increasing expectations for 
quality of life, treatment of sacral tumors now emphasizes not only complete tumor 
resection but also postoperative recovery of neurological function and quality of life. 
The sacrifice of sacral nerve roots during surgery can severely impact bladder and 
bowel function, especially over longer survival periods. However, most existing 
studies only retrospectively describe the impact of nerve root ligation, with limited 
clinical applicability and predictive value. 
This prospective observational study aims to analyze postoperative motor 
function and neurogenic bladder/bowel outcomes in patients undergoing sacral tumor 
resection. The goal is to identify key factors influencing functional outcomes and to 
establish correlations between these outcomes and variables such as the level of sacral 
osteotomy and nerve root sacrifice. By doing so, we hope to provide higher-level 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
clinical evidence and offer surgeons a more scientific basis for individualized surgical 
planning. 
2. Who is eligible to participate? 
Inclusion criteria: 
1. 
Patients aged 12–80 years. 
2. 
Diagnosed with primary sacral tumors or metastatic lesions from 
solid malignancies. 
3. 
Voluntarily consent to participate and sign the informed consent 
form. 
Exclusion criteria: 
1. 
Medically unfit for surgery. 
2. 
History of diseases or surgeries that impair bowel or bladder 
function. 
3. 
Incomplete surgical records regarding sacral osteotomy or nerve root 
involvement. 
4. 
Pregnancy or lactation. 
5. 
Missing critical follow-up data or lost to follow-up. 
3. How many participants will be enrolled? 
Approximately 400 eligible participants will be enrolled in this study. 
4. How will the study be conducted? 
• 
Preoperative Screening: Medical history, physical examination, 
and imaging will confirm the diagnosis. 
• 
Informed Consent: Eligible and willing participants will sign this 
form. Declining participation will not affect your treatment. 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
• 
Data Collection: This is a non-interventional study. We will only 
collect clinical data at designated timepoints. 
Assessments include: 
Preoperative: 
• 
Basic information (age, gender, BMI, surgical history) 
• 
Frankel motor function grading 
• 
Cleveland Constipation Score & Wexner Incontinence Score 
• 
Anorectal manometry & rectal compliance tests 
• 
ICIQ-SF score & Saito urinary dysfunction grade 
• 
Uroflowmetry (Qmax, volume, time), urodynamics (bladder 
capacity, detrusor pressure), bladder ultrasound (post-void residual, 
compliance, wall thickness) 
• 
Pain (VAS) 
• 
Quality of life (QLQ-C30) 
• 
History of preoperative embolization or balloon occlusion 
Intraoperative: 
• 
Surgery duration, blood loss, osteotomy level, surgical approach 
• 
Blood transfusion, instrumentation, nerve root ligation, resection 
technique 
• 
Pelvic floor reconstruction, intestinal involvement, nerve adhesion 
Postoperative (2W, 3M, 6M, 12M): 
• 
Frankel motor function 
• 
Bladder and bowel function (as above) 
• 
Pain (VAS; standardized NSAID use; rescue opioid dose and 
timing) 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
• 
QLQ-C30 
• 
Complications: thrombosis, wound infection, dehiscence, 
hematoma, CSF leak, pneumonia, UTI 
• 
Psychological and economic burden 
• 
Tumor control: PFS, OS (MRI, symptoms), adjuvant therapy 
(regimen, dose, duration, adverse effects) 
5. Risks and discomforts 
As this is an observational study, there are no additional clinical risks beyond 
standard care. However, scheduled follow-up assessments may cause minor 
inconvenience. 
6. Potential benefits 
You may not receive direct benefit. However, participation will help improve 
future care for sacral tumor patients. Regular follow-up may also support your 
ongoing recovery and treatment. 
7. Alternatives 
Refusal to participate will not affect your standard care. Your doctor will 
recommend alternative treatments as appropriate. 
8. Costs 
All follow-up consultations by attending physicians or higher will be provided 
free of charge for study participants. 
9. Management of injury 
In the unlikely event that study-related harm occurs, medical care will be 
provided and legal responsibilities fulfilled, unless the harm results from 
noncompliance with the protocol. 

Organization's Unique Protocol  ID:25SL016  2025.06.01 
 
10. Voluntary participation and withdrawal 
You may decline or withdraw at any time without penalty or loss of benefits. 
Investigators may also terminate your participation if deemed necessary for your 
safety or study integrity. 
11. Confidentiality 
Your privacy will be strictly protected. Identifiable information will only be 
accessible to study investigators, regulatory authorities, and ethics committees as 
needed. Results may be published without disclosing personal information. 
12. Other 
If any circumstances arise (e.g., protocol deviation, study termination, health 
risks), the investigator may withdraw you from the study for your safety. 
13. Contact information 
Principal Investigator: Dr. X. Phone:  
For rights-related concerns, please contact the Ethics Committee of Hospital