The goal of this observational study is to evaluate the relationship between sagittal and spinopelvic radiological parameters of the spine and clinical outcomes in adolescents with Scheuermann's kyphosis (SK) by assessing dynamic and static balance, pain, quality of life, and body image. The main questions it aims to answer are: Is there a correlation between kyphosis severity, spinopelvic measurements, and balance scores in adolescents with Scheuermann's kyphosis? How do pain, body image, and quality of life relate to radiological parameters and clinical findings in these individuals? Are there significant differences in balance, spinopelvic parameters, body image, and quality of life between adolescents with Scheuermann's kyphosis and healthy controls?

Participants will undergo radiological evaluation of sagittal spine and spinopelvic parameters using standing lateral spinal radiographs, static and dynamic balance assessments to evaluate postural stability, pain assessment using validated pain scales, and quality of life and body image assessments through standardized questionnaires.

Researchers will compare Scheuermann's kyphosis patients and age-matched healthy controls to determine the impact of kyphosis severity on balance, body image, and quality of life.

Scheuermann's disease, also known as juvenile kyphosis or juvenile discogenic disease, is a hyperkyphotic condition of the spine involving the vertebral bodies and discs, defined by anterior wedging of 5 degrees or more in three or more consecutive vertebral bodies. Some studies suggest that a single wedged vertebra associated with irregular vertebral endplates is sufficient for diagnosis. The thoracic spine is most commonly affected, but involvement may also extend to the thoracolumbar/lumbar region. The estimated prevalence in the general population is 0.4-8%, with a similar male-to-female ratio.

The exact and universally accepted etiology of Scheuermann's kyphosis (SK) has yet to be determined. It is suggested that disproportionate vertebral endplate mineralization and ossification during growth lead to uneven vertebral body growth, ultimately resulting in kyphosis with the characteristic wedge-shaped vertebral bodies. Thoracic hyperkyphosis in individuals with flexible spines is typically compensated by non-structural hyperlordosis of the lumbar and cervical spine. The head and shoulders are positioned forward, and the deformity is relatively fixed, not resolving with hyperextension. Neurological examination is almost always normal. The diagnosis is often made in adolescents aged 12 to 17 years when parents notice a postural deformity or hunchback appearance. Pain in the affected hyperkyphotic region may be the reason for initial evaluation, which may worsen with standing and activity but typically resolves upon skeletal maturity. The extent and severity of pain vary based on the patient's age, disease stage, kyphosis location, and deformity severity. In addition to spinal deformity, these patients often experience tightness in the pectoral, hamstring, and iliopsoas muscles.

For imaging, standard standing lateral and anteroposterior spinal radiographs are essential. The kyphosis angle is measured on lateral radiographs using the Cobb method. The normal range of thoracic kyphosis, according to the Scoliosis Research Society (SRS), is 20°-40° using the Cobb method. Based on the apex of kyphosis, SK is classified as thoracic type if the apex is at T7-T9, thoracolumbar type if at T10-T12, and lumbar type in cases with progressive low back pain, decreased lumbar lordosis, and characteristic radiographic changes.

The importance of sagittal profile assessment in spinal pathologies is increasing. Neutral sagittal balance is evaluated on standing lateral spinal radiographs. Kyphotic deformities disrupt neutral sagittal balance. Increased kyphotic deformity causes the head to shift forward beyond the feet and pelvis, resulting in positive sagittal imbalance.

Balance includes static balance, which is the ability to maintain the body in a specific position; dynamic balance, which is the ability to maintain balance during movement; and postural stability, which is the ability to maintain orientation in relation to the surrounding environment. This mechanism involves a neuromuscular interaction that integrates information from proprioceptive, visual, and vestibular inputs to generate an appropriate motor response to keep the body's center of mass within the base of support. Morphological spinal deformities can alter head position, lead to asymmetric muscle activity around the spine, and shift the body's center of mass, affecting postural stability and balance performance. Therefore, postural stability and balance performance in upright standing may be altered in individuals with spinal deformities such as scoliosis and hyperkyphosis. A kyphotic posture may cause the center of mass to shift forward beyond stability limits, reducing postural balance and increasing fall risk. Dysfunction in somatosensory pathways may impair postural control mechanisms, potentially influencing the etiology or progression of scoliosis.

The literature associates different scoliotic curvatures with altered posturography and postural sway under both static and dynamic conditions, indicating varying degrees of balance impairment. Some studies suggest that the degree of balance dysfunction correlates with the severity of the scoliotic curvature. While previous studies on SK have examined the relationship between radiographic findings and clinical symptoms, the impact of abnormal thoracic kyphotic posture on static balance, and spinopelvic parameters between SK patients and age-matched controls, no study has compared kyphosis severity and spinopelvic measurements with balance scores, body image, and quality of life.

This study aims to investigate the relationship between sagittal and spinopelvic radiological parameters and clinical findings in adolescents with Scheuermann's kyphosis by evaluating dynamic and static balance, pain, quality of life, and body image. Additionally, changes in these parameters will be compared with those of healthy adolescents.

Inclusion Criteria:

• Adolescents aged 10 to 18 years
• Diagnosis of Scheuermann's kyphosis based on Sorensen criteria (for patient group)
• Healthy volunteers matched for age and sex (for control group)
• Ability to understand and comply with study procedures
• Informed consent obtained from participants and/or guardians

Exclusion Criteria:

• Neuromuscular disorders
• History of spinal surgery or traumatic spinal injury
• Scoliosis > 15° (Cobb angle)
• Vestibular, visual, or auditory impairments
• Lower extremity musculoskeletal disorders affecting gait or balance
• Cognitive or psychiatric conditions affecting participation
• Use of orthotic devices or braces
• Any other systemic condition affecting postural control

Adolescents aged 10 to 18 years, including individuals diagnosed with Scheuermann's kyphosis and age- and sex-matched healthy controls. All participants were recruited from the department of physical medicine and rehabilitation