Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity, and a subset of patients undergo surgical correction during adolescence, most commonly posterior spinal fusion (PSF). Although surgical treatment improves deformity and quality of life in the short and mid-term, its long-term impact on functional status in adulthood remains insufficiently understood.

This cross-sectional study aims to evaluate long-term outcomes in adults aged 25-40 years who underwent surgical treatment for AIS, compared with non-operated individuals with scoliosis and healthy controls. The study will assess limitations in daily functioning, musculoskeletal and respiratory function, pain, and compensatory mechanisms using standardized clinical measurements and questionnaires.

The findings are expected to provide insight into long-term functional consequences of AIS and support the development of targeted physiotherapy and preventive strategies for adults treated for scoliosis during adolescence.

Adolescent idiopathic scoliosis (AIS) is a structural spinal deformity associated with long-term alterations in musculoskeletal function, posture, and respiratory mechanics. In progressive cases, surgical correction using posterior spinal fusion (PSF) is performed during adolescence; however, long-term functional outcomes remain insufficiently characterized.

This observational, cross-sectional study compares adults with surgically treated AIS, conservatively treated AIS, and healthy controls. Participants will undergo a standardized assessment protocol including anthropometric measurements, clinical examination, and patient-reported outcomes.

Anthropometric assessment will include body height, sitting height, body mass, arm span, waist and hip circumference, lower limb length and asymmetry, and chest circumference at rest and maximal inspiration, with derived indices of body proportions.

Functional status will be assessed using an author-developed questionnaire based on the International Classification of Functioning, Disability and Health (ICF), capturing perceived limitations in body functions, activities, participation, and environmental factors.

Clinical evaluation will include assessment of spinal curvature and pelvic alignment using inclinometric and scoliometric methods, as well as range of motion (ROM) of the cervical spine, temporomandibular joint, and peripheral joints. Additional orthopedic functional tests will be performed to assess lumbopelvic and lower limb function.

Pain will be evaluated using validated scales and graphical mapping of pain distribution.

Respiratory assessment will include spirometry and flow-volume measurements conducted according to international standards, chest wall mobility assessment, and measurement of respiratory muscle strength (maximal inspiratory and expiratory pressures). In addition, diaphragm structure and function will be evaluated using ultrasound imaging. Measurements will include diaphragm thickness and thickening fraction during respiratory cycles, as well as diaphragmatic excursion during quiet and deep breathing, performed under standardized conditions. This assessment aims to provide an objective evaluation of diaphragmatic mechanics, which may be altered in individuals with thoracic deformity or after surgical stabilization of the spine.

Exploratory analyses will examine associations between clinical variables and functional outcomes. The study aims to provide a comprehensive characterization of long-term functional status and inform targeted rehabilitation strategies.

Inclusion Criteria:

• Female, age 25-40
• AIS diagnosed before age 18 (Cobb angle >35°)
• Operated group: PSF, 10-25 years post-surgery
• Informed consent

Exclusion Criteria:

• Surgery other than PSF
• Surgery performed in adulthood

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