Study designCross-sectional and clinical measurement.ObjectiveTo evaluate upper extremity function and its relation to the curve pattern in idiopathic scoliosis.Summary of background dataPostural alterations and trunk distortions-caused by three-dimensional deformity itself in idiopathic scoliosis-may lead to functional changes in the upper extremity of subjects.MethodsHandgrip, pulp and lateral pinch strengths, hand dexterity, hand reaction time, coordination of upper extremity, upper extremity performance, throwing accuracy, and self-reported upper extremity disability were evaluated in 96 subjects. These subjects were divided into 3 groups: 47 with main thoracic curve pattern scoliosis (Lenke type 1), 31 with thoracolumbar/lumbar curve pattern scoliosis (Lenke type 5), and 18 unaffected (healthy control). Comparisons were performed between these three groups.ResultsThe thoracic scoliosis group showed a significant decrease in concave lateral pinch strength, concave hand dexterity of turning, coordination of the upper extremities, and concave hand reaction time than the thoracolumbar/lumbar scoliosis group (p<0.05). Bilateral handgrip strengths decreased in thoracic scoliosis group when compared to healthy controls. Healthy individuals demonstrated greater throwing accuracy than individuals with scoliosis.ConclusionsUpper extremity function was found to be affected based on the curve pattern. Individuals with main thoracic curves are likely to have deteriorated upper extremity function, especially for hand-specific motor skills, on the concave side, when compared to lumbar curves and healthy controls.Level of evidenceLevel III.