Risk factors and foot biomechanical characteristics of idiopathic scoliosis: a cross-sectional study

Abstract

Idiopathic scoliosis (IS) caused by an unknown etiology is prevalent in primary and secondary school students. Early detection and prevention are challenging because of the limited knowledge about controllable risk factors and imbalances in body mechanics. In this study, we examined the potential causative factors of IS and its correlation with foot mechanics among 7-14 year-old students in northern Jiangsu Province, China. Based on a stratified whole cluster sampling, 4387 students were examined, of whom of whom 165 were diagnosed with scoliosis. Through logistic regression analysis, the following risk factors were identified: age group, female gender, thinness, unsuitable desk and chair heights, heavy schoolbags, backpack carried on one shoulder, daily sedentary time ≥ 10 h, daily playing electronic products time ≥ 2 h, daily physical activity time < 1 h, sports programs with unilateral limb power, lumbar and back fatigue, unequal thickness of worn soles on both feet and flat foot. When compared to healthy people, IS patients exhibit foot biomechanics characterized by a diagonal distribution of bilateral weight-bearing and walking instability, as well as poor balance function if they have an abnormal foot type, as in the case of flat foot. Our study revealed that the detection rate of scoliosis in primary and secondary school students in northern Jiangsu Province, China, is relatively is on the high side, so it is necessary to strengthen education and screening, concentrate on female students, and provide guidance on how to develop a healthy lifestyle and learning habits. Assessment of plantar pressure distribution and postural symmetry is an effective means of predicting scoliosis. Plantar pressure analysis can serve as an additional tool for assessing the risk of scoliosis.

Keywords: Epidemiology; Foot biomechanics; Idiopathic scoliosis; Primary and secondary school students; Risk factors.

Fig. 1

The butterfly diagram formed by the movement of the body center of gravity during walking. (a) Butterfly diagram of a healthy subject with a regular butterfly pattern and smooth gait, with the body center of gravity centered at the center of the butterfly. (b) Butterfly diagram of an IS patient (the patient’s spine curves to the left); the butterfly pattern tends to be disordered, gait is severely imbalanced, and the body center of gravity is concentrated on the left front side.

Fig. 2

Schematic diagram of the COP trajectory (white line). (a–e) The four temporal phases of the stance period: ICP, initial contact phase; FFCP, forefoot contact phase; FFP, foot flat phase; FFPOP, forefoot push off phase. (f) Schematic diagram of the Cartesian coordinate system.

Fig. 3

Flow diagram showing the screening process for idiopathic scoliosis.

Fig. 4

Line diagram showing the detection rates for the male group and the female group and the total detection rate for each age group.

Fig. 5

Effects of foot type on scoliosis. (A) Cobb’s angle of scoliosis patients with different foot types. (B) The body center of gravity offset distance of scoliosis patients with different foot types. (C) COP displacement distance of different foot types in the main curve concave side foot. (D) COP displacement distance of different foot types in the main curve convex side foot. COP, Centre of pressure. The same letter (a or b) indicates that the difference between two comparisons is not significant (P < 0.05); different letters indicate that the difference between two comparisons is significant (P > 0.05).