In the sagittal plane, the average kyphosis angle between the superior endplate of the T1 vertebra and the inferior endplate of the T12 vertebra is approximately 40 degrees. A thoracic spine angle greater than 45 degrees is defined as hyperkyphosis. The most common types of hyperkyphosis observed in juveniles and adolescents are Scheuermann's kyphosis, postural hyperkyphosis, and congenital hyperkyphosis.

Postural hyperkyphosis is the most prevalent form among these types. It results from the weakness of the muscles responsible for maintaining an upright posture and occurs due to external forces acting on the spine. The curvature of the spine in this condition is not rigid and can generally be corrected when the individual is asked to stand upright. Postural hyperkyphosis is typically seen during adolescence.

An increased thoracic kyphosis angle in postural hyperkyphosis can affect scapular kinematics, potentially leading to shoulder pathologies later in life, such as impingement syndrome, rotator cuff tendinopathy, rotator cuff tears, glenohumeral instability, and adhesive capsulitis. Additionally, hyperkyphosis can negatively affect body image and overall quality of life. If it begins in childhood and remains untreated, hyperkyphosis may persist into adulthood and contribute to increased healthcare expenditures. Given the growing prevalence of technology dependence and its association with rising hyperkyphosis incidence, early management of this deformity during juvenile and adolescent periods is essential in terms of both health and economic outcomes. In managing postural hyperkyphosis, it is important to address not only the angular correction of the deformity but also to consider the entire spine within the kinetic chain model.

The kinetic chain model is a biomechanical concept that defines the body as a system of interconnected segments. Any dysfunction within one segment of the kinetic chain can affect the quality of movement in both the upper and lower segments. The scapula serves as a foundation within this model, acting as a force transmitter that converts potential energy generated by muscles into kinetic energy in the upper extremity. Hyperkyphosis can lead to scapular protraction and downward rotation, disrupting the normal positioning of the scapula. As a result, joint range of motion, strength, and performance in the upper extremity may be negatively affected.

Studies in the literature have shown that scapular positioning and movements play a critical role in upper extremity function. However, no study has been found that specifically investigates the impact of altered scapular position on upper extremity performance in children with thoracic hyperkyphosis. Considering the increasing prevalence of thoracic hyperkyphosis in children due to rising technology addiction, and the potential for this deformity to contribute to upper extremity pathologies in adulthood, identifying its effects is crucial for improving children's physical performance and reducing future healthcare costs.

Inclusion Criteria:

• Being between 7-14 years old
• Thoracic kyphosis angle (Cobb) on lateral radiograph: ≥45˚ or kyphosis index ≤13

Exclusion Criteria:

• Those who have had major surgery or trauma related to the musculoskeletal system, especially the spine and upper extremities
• Difficulty in perceiving commands
• Rigid deformity in the spine (Scheuermann kyphosis)
• Congenital deformity

Children with thoracic hyperkyphosis will be included in our study.