Longitudinal Changes in Spinopelvic Alignment and Sagittal Balance After Bariatric Surgery in Patients With Morbid Obesity: A Prospective Observational Study

NCT07794553 | Active Not Recruiting DMC

• 1 other identifier: MarmaraUSpine01
• Study Type: observational
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this prospective observational study is to understand how major weight loss after bariatric surgery may be associated with changes in the way the spine and pelvis are aligned in adults with morbid obesity. The spine and pelvis work together to support the body and help maintain balance during standing and walking. In people with severe obesity, increased body weight and changes in body shape may affect posture, the position of the pelvis, the curves of the spine, and the way the upper body is balanced over the pelvis. Bariatric surgery can result in substantial weight loss, but it is not yet fully understood how these changes in body weight may affect the relationship between the spine and pelvis over time. This study will follow patients undergoing bariatric surgery and will evaluate them before surgery and again at approximately 3, 6, and 12 months after surgery. The study is observational. This means that the researchers will observe, measure, and record changes occurring during the patients' clinical course rather than assigning participants to a specific treatment for the purpose of this study. The main question of the study is whether spinopelvic alignment and overall body balance change during the first year after bariatric surgery as patients lose weight. "Spinopelvic alignment" refers to the relationship between the spine and the pelvis. The pelvis forms the base on which the spine is positioned, and changes in pelvic position can be related to changes in the curves and orientation of the spine. "Sagittal balance" refers to how the head, trunk, spine, and pelvis are balanced from front to back when the body is viewed from the side. Researchers will evaluate measurements describing the position and orientation of the pelvis, the curvature and alignment of the spine, and the relationship between the spine and pelvis. Measurements obtained before bariatric surgery will be compared with those obtained at approximately 3, 6, and 12 months after surgery. By following the same patients at several different time points, the researchers will be able to determine whether any changes occur early after surgery, develop gradually as weight loss continues, or remain relatively stable throughout the first postoperative year. The study will also examine the relationship between postoperative weight loss and changes in spinopelvic measurements. Patients may respond differently to major weight loss. Some people may develop measurable changes in posture or spinal and pelvic alignment, while others may show little or no change. The purpose of the study is therefore not to assume that weight loss will improve every spinal or pelvic measurement, but to objectively describe what happens to these measurements during the period of substantial weight reduction after bariatric surgery. Understanding these changes may be important because body weight, posture, spinal curvature, pelvic position, and mechanical loading are closely related. Changes in how the body is balanced may potentially influence the mechanical demands placed on the spine, pelvis, and surrounding muscles and joints. The results may improve understanding of the musculoskeletal effects of severe obesity and major weight loss. They may also provide information for future research on the relationship between obesity, weight reduction, posture, spinal alignment, pelvic position, spinal balance, and musculoskeletal health. For patients and families, the study can be summarized simply as follows: the researchers want to find out whether losing a substantial amount of weight after bariatric surgery changes the way the spine and pelvis are positioned and balanced. Measurements taken before surgery will be compared with measurements taken during follow-up at 3, 6, and 12 months. By observing the same patients throughout the first year after surgery, the researchers hope to better understand how the spine and pelvis adapt as body weight decreases.

Conditions

Obesity; Spine Condition

Keywords

Bariatric Surgery; Pelvic Tilt; Lumbar Lordosis; Pelvic Alignment; Spinal Alignment; Sagittal Balance; Spinopelvic Parameters; Weight Loss

Outcome Measures

Primary Outcomes (1)

• Change From Baseline in Sagittal Vertical Axis (SVA)

  Sagittal Vertical Axis (SVA) will be measured in millimeters on standing lateral whole-spine radiographs as the horizontal distance between the C7 plumb line and the posterosuperior corner of the S1 vertebral body. Positive values indicate anterior translation of the trunk relative to the sacrum. Change from the preoperative baseline will be calculated at each postoperative follow-up.

  Baseline (preoperative), and 3, 6, and 12 months after bariatric surgery

Secondary Outcomes (5)

• Change From Baseline in Pelvic Incidence-Lumbar Lordosis (PI-LL) Mismatch

  Baseline (preoperative), and 3, 6, and 12 months after bariatric surgery

• Change From Baseline in Pelvic Tilt (PT)

  Baseline (preoperative), and 3, 6, and 12 months after bariatric surgery

• Change From Baseline in Sacral Slope (SS)

  Baseline (preoperative), and 3, 6, and 12 months after bariatric surgery

• Change From Baseline in Lumbar Lordosis (LL)

  Baseline (preoperative), and 3, 6, and 12 months after bariatric surgery

• Change From Baseline in T1 Pelvic Angle (TPA)

  Baseline (preoperative), and 3, 6, and 12 months after bariatric surgery

Study Arms (1)

Patients Undergoing Bariatric Surgery

Adults with morbid obesity undergoing bariatric surgery as part of routine clinical care will be prospectively followed. Spinopelvic alignment, spinal and pelvic radiographic parameters, and global sagittal balance will be evaluated before surgery and at approximately 3, 6, and 12 months after surgery to assess longitudinal changes associated with postoperative weight loss.

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adults with morbid obesity who are scheduled to undergo bariatric surgery as part of routine clinical care will be prospectively enrolled and followed. Participants will undergo serial assessment of spinal, pelvic, and spinopelvic alignment using standing radiographs obtained during the preoperative period and at approximately 3, 6, and 12 months after bariatric surgery. The study population is intended to characterize longitudinal changes in spinopelvic alignment and sagittal balance associated with substantial postoperative weight loss.

You may qualify if:

• Adults aged 18 years or older.
• Patients with morbid obesity who are scheduled to undergo bariatric surgery according to routine clinical indications.
• Ability to stand independently for standardized weight-bearing radiographic assessment.
• Availability of an appropriate preoperative standing whole-spine radiograph for spinopelvic measurements.
• Planned postoperative clinical and radiographic follow-up at approximately 3, 6, and 12 months.
• Ability and willingness to participate in the prospective follow-up protocol.

You may not qualify if:

• Previous spinal fusion, spinal instrumentation, or major spinal deformity surgery that may substantially alter spinopelvic alignment.
• Previous major pelvic surgery or structural pelvic disorder preventing reliable spinopelvic measurements.
• Neurological or neuromuscular disorders that substantially affect standing posture or sagittal balance.
• Inability to obtain technically adequate standardized standing radiographs.
• Pregnancy at a time when radiographic assessment would otherwise be required.
• Development of a major spinal, pelvic, or lower-extremity condition or surgery during follow-up that may independently alter spinopelvic alignment.
• Incomplete or unavailable radiographic data required for longitudinal analysis.

Sponsors & Collaborators

• Marmara University: lead

Study Sites (1)

Department of Orthopaedic Surgery and Traumatology, Marmara University, Pendik Training and Research Hospital, İstanbul, Turkey

Istanbul, Pendik, 34899, Turkey (Türkiye)

Location

Related Publications (1)

• Does extreme weight loss after bariatric surgery alter spinopelvic parameters and ameliorate back pain? A retrospective case study Fırat Emin Özdemir1, Hakan Şeşen1, İsmail Demirkale3, Doğan Öztürk2, Hakan Buluş2, Murat Altay1 1Department of Orthopedics and Traumatology, University of Health Sciences, Atatürk Sanatoryum Training and Research Hospital, Affiliated by Gülhane School of Medicine, Ankara, Türkiye 2Department of General Surgery, University of Health Sciences, Atatürk Sanatoryum Training and Research Hospital, Affiliated by Gülhane School of Medicine, Ankara, Türkiye 3Department of Orthopedics and Traumatology, University of Health Sciences, Prof. Dr. Cemil Taşcıoğlu City Hospital, Affiliated by Hamidiye School of Medicine, Istanbul, Türkiye

  BACKGROUND

MeSH Terms

Conditions

Obesity; Lordosis; Weight Loss

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Spinal Curvatures; Spinal Diseases; Bone Diseases; Musculoskeletal Diseases; Body Weight Changes

Study Officials

• Muhammed F Serttaş, Medical Specialist, Consultant

  Department of Orthopaedic Surgery and Traumatology, Marmara University, Pendik Training and Research Hospital, İstanbul, Turkey

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Target Duration: 12 Months
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 23, 2026
• First Posted: August 31, 2026
• Study Start: September 7, 2026
• Primary Completion (Estimated): August 1, 2027
• Study Completion (Estimated): August 1, 2027
• Last Updated: September 16, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)