Influence of the Weight of a School Backpack on Spinal Curvature in the Sagittal Plane of Seven-Year-Old Children

Table 3

Summary of the parameters characterizing the children’s body postures.

	Backpacks lighter than 10% of body weight			Backpacks heavier than 10% of body weight			Mann-Whitney test
	Mean	Range	SD	Mean	Range	SD
ThS (mm)	375.4	350.3–400.5	25.1	357.0	320.7–393.3	36.3	2.223	0.026
THL (mm)	230.4	212.5–248.3	17.9	223.4	203.7–243.1	19.7	1.252	0.211
LS (mm)	107.0	90.6–123.4	16.4	98.4	77.7–119.1	20.7	1.454	0.146
KKP (deg.)	47.4	33.8–61.0	13.6	43.8	31.1–56.5	12.7	1.414	0.157
KKL (deg.)	26.6	12.3–40.9	14.3	23.9	12.2–35.6	11.7	1.112	0.266
TTI (deg.)	4.2	2.3–6.1	1.9	3.4	1.4–5.4	2.0	1.345	0.179
SCR (deg.)	24.5	14.7–34.3	9.8	19.5	9.3–29.7	10.2	1.927	0.054

ThS (mm): total length of the spine.
THL (mm): length of the thoracic spine.
LS (mm): length of the lumbar spine.
KKP (degrees): thoracic kyphosis angle, calculated from the intersection of the tangents extending between the spinous processes of Th1 and Th2 and Th11 and Th12.
KKL (degrees): angle of lumbar lordosis, calculated from the intersection of the tangents extending between the spinous processes of L1 and L2 and L5 and S1.
TTI (degrees): total angle of anterior trunk inclination.
SCR (degrees): sacral angle in the study group (sacral angle is defined as the angle between the line connecting the spinous processes S1 and S3 and the frontal plane).
SD: standard deviation; : Mann-Whitney test; : significance level.