Introduction

The human foot is an important part of the static-dynamic motor organ and is shaped uniquely in each individual. Its construction and setting have major impacts on the quality of gait and postural stability. A properly arched foot is elastic and flexible and absorbs microtrauma and shocks during locomotion, making the gait light and springy [1].This state is conditioned by the proper capacity of muscles and ligaments and proper construction of the osteoarticular system. Down syndrome (DS), also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21 [2]. It is associated with characteristic symptoms and physical features recognized in the human since the moment of the birth [3]. Developmental abnormalities, muscular hypotonus, and excessive flexibility of the ligamentous articular system cause postural problems in these individuals. Musculoskeletal function, postural stability, and coordination skills may be compromised or impaired [4–۸]. Because the quality of the gait is reduced in individuals who have DS, their physical activity is often restricted [9, 10]. Cioni et al. [11] observed that strength of the main antigravity muscles, the knee extensors in children and adolescents with Down syndrome, is markedly affected during the execution of slow isokinetic movements. Bolach et al. [12] emphasized that the degree of intellectual disability has a major impact on the results of motor capacity tests. The examination by means of the Eurofit Special test (while being a battery of motor fitness tests resulting from a 10-year project of the Committee of Experts for Sports Research and being comprised of strength, speed, flexibility, and balance) showed worse results in children aged 11 to 14 years with moderate intellectual disabilities compared to their peers with mild mental disabilities. An additional issue for people with DS is their predisposition to excessive weight gain resulting from genetic condition, metabolic and hormonal disorders, deficiency of movement, and an inability to diagnose their own nutritional needs [13–۱۵]. These aspects often determine the emergence and deterioration of pathological changes in the structure of the feet that are difficult to treat and rehabilitate. The aim of this study was the analysis of selected features of the foot structure in boys with DS versus their age- and gender-matched peers without Down syndrome.