The school backpack and physical parameters relationship with spinal alignment in the sagittal plane. Are changes in the design of school backpacks for younger school-age children necessary?

Abstract Introduction. A school backpack, as an off-axis external load, induces changes in the spinal alignment within the compensatory mechanism. Objective. Considering the above, the aim of this study was to examine how the angular parameters of the sagittal plane, the thoracic kyphosis angle, and the lumbar lordosis angle change under normative school backpack load. Additionally, the study aimed to assess how carrying a backpack affects the symmetry of foot load distribution in children. Materials and Methods. The study included 75 children (45 girls and 30 boys) aged 7-9 years (Mean = 8.48; SD = 0.89). A backpack model closely resembling those currently available on the Polish market was developed. The backpack’s weight was standardized, and sagittal plane measurements were taken using a digital inclinometer. The symmetry of load distribution was assessed using a stabilometric platform, and the endurance of postural muscles was evaluated with the Matthias test. The study only included backpacks that met the standard weight range of 10–15% of the child’s body weight. Results. Three previously undescribed types of compensation were identified: flexion type, extension type, and balanced type. Only in the balanced type did the endurance of postural muscles not significantly decrease after wearing the school backpack. Conclusions. It is necessary to modify the design of school backpacks to prevent spinal alignment changes in the sagittal plane, even within normative or excessive load values. Proper spinal curvatures are crucial for maintaining an upright body posture. Non-invasive, modern technologies based on thermal imaging should be considered as potential solutions.