Diurnal variation of body height in children with idiopathic scoliosis

Abstract

BACKGROUND:

Body height (BH) measurement is an important part of the clinical evaluation of children with idiopathic scoliosis (IS) as its progression is defined based on the observation of a growth spurt.

OBJECTIVE:

The aim of the study is to assess diurnal variation of BH in children with IS.

METHODS:

BH was measured in 98 children with IS (Cobb angle: 10 ${}^{\circ}$ –52 ${}^{\circ}$ , mean 21.2 ${}^{\circ}$ $\pm$ 9.9 ${}^{\circ}$ ) both in standing and sitting position. The measurements were performed 4 times a day – between: (1) 7:00 and 8:00; (2) 11:00 and 12:00; (3) 15:00 and 16:00 and (4) 19:00 and 20:00.

RESULTS:

A significant decrease in BH during the day was observed in both standing and sitting positions ( $p<$ 0.001). The highest decrease in height was observed between the measurements performed between 7:00 and 8:00 and measurements carried out in the evening (19:00–20:00). For standing, the mean loss of height was 0.7 cm ( $\pm$ 0.7), i.e. 0.43% of initial standing height, for sitting the mean decrease in height was 0.7 cm ( $\pm$ 0.7), i.e. 0.79% of initial sitting height.

CONCLUSIONS:

BH decreases in children with IS during daytime. Due to diurnal BH variation, the time of the day should be recorded when measuring patients with IS.

Keywords

Idiopathic scoliosis body height diurnal variation treatment evaluation progression

1. Introduction

Idiopathic scoliosis (IS) is a structural, growth-related deformation of the spine with unknown etiology [1, 2]. Idiopathic scoliosis appears most commonly in the periods of growth spurts [1]. The scoliotic curve progresses most rapidly at the beginning of puberty [3, 4].

The treatment of IS, either conservative or surgical, depends on deformation magnitude and risk of progression [1]. The risk of progression of IS is closely related to the longitudinal growth of the spine [5, 6, 7, 8]. The pubertal growth spurt begins with accelerated longitudinal growth of the limbs, causing temporary body disproportion (long limbs versus short trunk). Then, the longitudinal growth of the axial skeleton follows [1].

Since the highest progression of IS is observed at growth spurts and peak height velocity [1, 7, 9, 10], it is essential to evaluate the current and to predict the future spinal growth of patients [5, 10, 11]. An important question is determining whether the patient is before or after her or his peak growth velocity of sitting height [12, 13]. Therefore, the height measurement is an indispensable part of clinical evaluation of children with IS. To differentiate between the spinal growth versus the one of the lower limbs, the body height (BH) measurement should be performed both in standing and sitting position [13].

The reliability of growth assessment may be limited by measurement error due to physiological diurnal variation of body height [14, 15]. Differences of even 0.5 cm could lead to incorrect diagnosis of slow, fast or normal growth velocity [16, 17, 18, 19]. However, diurnal variation of height is largely ignored in clinical practice. It is also ignored in studies evaluating height loss associated with progression or magnitude of IS [9, 14, 15, 20].

Diurnal variation of body height in children with IS has been analyzed only once by Zetterberg et al. in the paper published in 1983 [21]. The authors evaluated 38 children with scoliosis and revealed the mean decrease in standing height of 10.8 mm ( $\pm$ 5.7), while the sitting height decreased by a mean of 8.8 mm ( $\pm$ 0.7) within one day [21].

Taking into account the usefulness of the height measurements in planning the treatment of scoliotic patients as well the paucity of the actual data concerning body height changes in IS patients, we think that an analysis of diurnal variation of body height in the current IS population is needed. First, additional analysis of relationships between variation of body height during the day and severity or type of the curve would be of great value. Second, the accelerated puberty and peak growth velocity in adolescents in the 21 ${}^{\rm st}$ century [22] might potentially influence the diurnal variation in body height.

Thus, the aims of the study were: (1) to assess diurnal variation of body height in children and adolescents with IS; (2) to determine the intra-rater reliability of height measurements in children and adolescents with IS; (3) to analyze the correlation between diurnal height changes in children and adolescents with IS and severity of the curve; (4) to determine differences in diurnal variations in body height in children and adolescents with different curve types in IS and different conservative treatment methods.

2. Material and methods

2.1 Material

The study comprised 98 consecutive non-operatively treated Caucasian Mid-European in-patients with IS (82 females, 16 males; age: 9–18 years, mean 14.4 years $\pm$ 1.8; Cobb angle: 10 ${}^{\circ}$ –52 ${}^{\circ}$ , mean 21.2 ${}^{\circ}$ $\pm$ 9.9). There were 22 patients with single right thoracic (T), 35 with single left thoracolumbar (TL), 20 with single left lumbar (L) and 21 with double-curve right thoracic and left lumbar (DTL) scoliosis. All patients were treated with scoliosis-specific physiotherapy [1], while 27 used Cheneau brace (20 hours per day; according to SOSORT recommendations [1]).

2.2 Methods

Body height was measured in all subjects both in standing and sitting position. The measurements were performed using a wall-mounted analogue stadiometer (ADE GmbH and Co, Hamburg, Germany; scale: 1 mm). First, the subjects were standing barefoot with knees extended and feet hip-width apart. The second measurement was performed in sitting on a stool with knees and hips flexed at 90 ${}^{\circ}$ . In both positions the subjects were requested to stand or sit in natural, comfortable, and erected position and look at a designated point ahead placed at eye level [11, 14, 15]. The children were not asked to adopt a corrected posture. The children were also requested to breathe naturally without holding their breath.

The measurements were performed 4 times a day once each time: (1) measurement 1 (M1) – just after getting up between 7:00 and 8:00; (2) measurement 2 (M2) – between 11:00 and 12:00; (3) measurement 3 (M3) – between 15:00 and 16:00 and (4) measurement 4 (M4) – between 19:00 and 20:00. On the measurements day, the subjects did not participate in any type of physiotherapy or physical activity. The children treated with brace took it off before and put it back on immediately after the measurements.

Table 1
Mean values of body height measured in standing and sitting during each of 4 periods of the day

Height (cm) ( $n=$ 98)	M1 (7:00–8:00)	M2 (11:00–12:00)	M3 (15:00–16:00)	M4 (19:00–20:00)	$p$ -value
Standing	164.7 $\pm$ 10.7	164.2 $\pm$ 10.7	164.1 $\pm$ 10.6	164.0 $\pm$ 10.7	$<$ 0.001 ${}^{*}$
Sitting	85.9 $\pm$ 5.6	85.5 $\pm$ 5.7	85.3 $\pm$ 5.6	85.2 $\pm$ 5.5	$<$ 0.001 ${}^{*}$

Note: significant differences in repeated measures ANOVA are marked in bold; post hoc analysis for standing: M1 $>$ M2, M3, M4 ( $p<$ 0.001); M2 $>$ M4 ( $p=$ 0.30); for sitting M1 $>$ M2, M3, M4 ( $p=$ 0.01, $p<$ 0.01, $p<$ 0.001, respectively).

Table 2

The correlation between the height difference observed between measurements 1 and 4 in standing and sitting and Cobb angle, age, height and body mass for the whole group (G), single right thoracic (T), single left thoracolumbar (TL), single left lumbar (L) and double-curve (DTL) scoliosis (the differences were determined by calculating measurement 1 (M1) minus measurement 4 (M4), positive differences)

		Cobb angle		Age		Height		Body mass
		RS	$p$ -value	RS	$p$ -value	RS	$p$ -value	RS	$p$ -value
G	Standing	0.11	0.29	$-$ 0.05	0.61	$-$ 0.01	0.93	$-$ 0.01	0.92
$n=$ 98	Sitting	0.11	0.29	0.177	0.08	0.178	0.08	0.22	0.03
T	Standing	0.16	0.48	0.2	0.37	$-$ 0.04	0.87	$-$ 0.06	0.79
$n=$ 22	Sitting	0.32	0.15	0.18	0.42	0.01	0.96	0.05	0.82
TL	Standing	0.06	0.74	$-$ 0.13	0.45	0.06	0.73	$-$ 0.07	0.7
$n=$ 35	Sitting	0.1	0.56	0.19	0.26	0.37	0.03	0.2	0.26
L	Standing	$-$ 0.07	0.77	$-$ 0.01	0.95	$-$ 0.08	0.74	$-$ 0.21	0.38
$n=$ 20	Sitting	$-$ 0.09	0.72	0.13	0.58	$-$ 0.09	0.72	0.1	0.67
DTL	Standing	0.43	0.05	$-$ 0.08	0.72	0.03	0.9	0.13	0.56
$n=$ 21	Sitting	$-$ 0.28	0.22	0.36	0.11	0.13	0.59	0.54	0.01

Note: RS – R Spearman correlation; significant correlations are marked in bold.

All the measurements were performed by one observer (first author), who was blinded to the results of prior measurements of body height of the patient. Before the main study, the intra-observer reliability was tested by measuring both standing and sitting height twice, with one-week interval, in 22 children aged 10–14 years (mean 10.6 years $\pm$ 1.0, mean height 1.45 m $\pm$ 0.1, mean weight 34.7 kg $\pm$ 7.4, mean BMI 16.2 $\pm$ 2.0). The children were randomly chosen at the hospital. All the measurements were carried out between 7:00 and 8:00 in the morning.

Before each patient was enrolled into the study, a written consent from her/his parents had been obtained. The study protocol has been reviewed and approved by the local ethical committee of the Józef Rusiecki University College in Olsztyn (research no. BS/F/2015/1).

2.3 Statistical analysis

The statistical analysis was made with Statistica 10 software (StatSoft, Poland). In the statistical analysis the following were used: descriptive statistics, Shapiro-Wilk test to evaluate normal distribution of the data, repeated measures ANOVA to compare 4 subsequent measurements of body height, Tukey test as post hoc analysis, Spearman correlation and Mann-Whitney U test as nonparametric tests. The value $\alpha<$ 0.05 was adopted as the level of significance while CI for estimates was 95%. The reliability of the intra-rater measurements was quantified by the intraclass correlation coefficient (ICC 2.1) [23, 24] and standard error of measurements (SEM) were assessed [25].

3. Results

3.1 Pilot reliability study

Excellent reliability for BH measurements was revealed both for standing and sitting, with an ICC of 0.99 for both positions and SEM of 0.40 cm for standing and 0.28 cm for sitting [23, 25].

3.2 Diurnal changes in body height – whole group

A significant decrease in body height during the day was observed in both standing and sitting in the entire group of patients (Table 1).

The highest difference in BH (statistically significant) in both standing and sitting was observed between measurements performed just after getting up (M1) and measurements carried out in the evening (M4) ( $p<$ 0.001 for both positions). The standing height between M1 and M4 decreased by a mean of 0.7 cm ( $\pm$ 0.7), i.e. 0.43% of initial standing height (164.7 cm). The sitting height between M1 and M4 decreased by a mean of 0.7 cm ( $\pm$ 0.7), i.e. 0.79% of initial sitting height (85.9 cm).

Figure 1.

The correlations between changes in body height and the Cobb angle in standing (the differences were determined by calculating measurement 1 (M1) minus measurement 4 (M4), positive differences).

Figure 2.

The correlations between changes in body height and the Cobb angle in sitting (the differences were determined by calculating measurement 1 (M1) minus measurement 4 (M4), positive differences).

The changes in height revealed between M1 and M4 were as follows: for standing (1) no change – 21 subjects, (2) decrease by up to 0.5 cm – 24 subjects, (3) decrease by 0.6–1.0 cm – 30 subjects, (4) decrease by 1.1–1.5 cm – 13 subjects, (5) decrease by 1.6–2.0 cm – 4 subjects, (6) decrease by 2.1–2.5 cm – 2 subjects, (7) increase by up to 1.0 cm – 4 subjects; for sitting (1) no change – 21 subjects, (2) decrease by up to 0.5 cm – 22 subjects, (3) decrease by 0.6–1.0 cm – 32 subjects, (4) decrease by 1.1–1.5 cm – 11 subjects, (5) decrease by 1.6–2.0 cm – 4 subjects, (6) decrease by 2.1–2.5 cm – 2 subjects, (7) increase by up to 0.5 cm – 2 subjects, (8) increase by 0.6–1.0 cm – 4 subjects.

Table 3

Mean values of height measurements performed in standing and sitting in children treated with and without brace during each of 4 periods of the day

		M1 (7:00–8:00)	M2 (11:00–12:00)	M3 (15:00–16:00)	M4 (19:00–20:00)	$p$ -value
		Height (cm)
Brace	Standing	165.3 $\pm$ 9.9	165.0 $\pm$ 9.8	164.8 $\pm$ 9.8	164.7 $\pm$ 9.8	$<$ 0.001
$n=$ 27	Sitting	86.6 $\pm$ 5.5	86.1 $\pm$ 5.6	85.9 $\pm$ 5.4	85.9 $\pm$ 5.4	$<$ 0.001
Without brace	Standing	164.4 $\pm$ 11.0	163.9 $\pm$ 11.1	163.8 $\pm$ 11.0	163.7 $\pm$ 11.1	$<$ 0.001
$n=$ 71	Sitting	85.6 $\pm$ 5.7	85.2 $\pm$ 5.7	85.1 $\pm$ 5.7	84.9 $\pm$ 5.6	$<$ 0.001

Note: Significant differences in repeated measures ANOVA are marked in bold; post hoc Tukey test for B – standing: M1 $>$ M3, M4 ( $p=$ 0.001, $p<$ 0.001, respectively); sitting M1 $>$ M2, M3, M4 ( $p<$ 0.001); for NB – standing: M1 $>$ M2, M3, M4 ( $p<$ 0.001); sitting M1 $>$ M2, M3, M4 ( $p<$ 0.001); M2 $>$ M4 ( $p=$ 0.001).

The largest difference in BH between the consecutive measurements was for M1 and M2 with the mean difference of 5 mm ( $p<$ 0.001) for standing and 4 mm ( $p=$ 0.01) for sitting (Table 1). The differences between M2 and M3 or M3 and M4 were not statistically significant for both the sitting and the standing body height (Table 1).

There was no significant correlation between the change in height observed between M1 and M4 and the Cobb angle, age, height as well as body mass with the exception of the positive significant correlation between body mass and decrease of the sitting height between M1 and M4 (Table 2, Figs 1 and 2).

3.3 Diurnal changes in body height – pattern observed for the brace and the no-brace

A significant decrease in the height during a day was observed in children treated with brace and children treated only with physiotherapy (Table 3). For each time interval, there were no significant differences between height changes observed in children treated with brace versus those without brace (Table 4).

3.4 Diurnal changes in body height – the influence of the curve type in IS

A significant decrease in the height during a day was observed for T, TL, DTL (standing and sitting, $p<$ 0.001) and L curve types (standing, $p<$ 0.001). The differences in height were significantly different between periods for all curve types in both positions except for the height measured in sitting in patients with single left lumbar scoliosis (L) (Table 5).

Table 4
The comparison of the mean height loss observed in children with and without brace for each comparison interval

Measurements		Brace	Without brace	$p$ -value
		$n=$ 27	$n=$ 71
M1–M2	Standing	0.32 $\pm$ 0.82	0.6 $\pm$ 0.81	0.16
	Sitting	0.48 $\pm$ 0.45	0.37 $\pm$ 0.68	0.37
M2–M3	Standing	0.18 $\pm$ 0.59	0.02 $\pm$ 0.76	0.58
	Sitting	0.19 $\pm$ 0.54	0.11 $\pm$ 0.61	0.4
M3–M4	Standing	0.07 $\pm$ 0.43	0.15 $\pm$ 0.53	0.48
	Sitting	0.07 $\pm$ 0.43	0.2 $\pm$ 0.57	0.30
M1–M3	Standing	0.5 $\pm$ 0.72	0.62 $\pm$ 0.79	0.62
	Sitting	0.67 $\pm$ 0.6	0.47 $\pm$ 0.77	0.29
M1–M4	Standing	0.57 $\pm$ 0.57	0.77 $\pm$ 0.74	0.22
	Sitting	0.74 $\pm$ 0.61	0.67 $\pm$ 0.75	0.63
M2–M4	Standing	0.26 $\pm$ 0.62	0.18 $\pm$ 0.89	0.8
	Sitting	0.26 $\pm$ 0.53	0.3 $\pm$ 0.63	0.88

Note: Mann-Whitney U test was used; M1 – measurements performed between 7:00 and 8:00; M2 – measurements performed between 11:00 and 12:00; M3 – measurements performed between 15:00 and 16:00; M4 – measurements performed between 19:00 and 20:00.

Table 5

Mean values of height measured in standing and sitting for single right thoracic (T), single left thoracolumbar (TL), single left lumbar (L) and double-curve (DTL) scoliosis for each of 4 periods of the day

		M1		M2		M3		M4		$p$ -value
		(7:00–8:00)		(11:00–12:00)		(15:00–16:00)		(19:00–20:00)
T	Standing	162.5	$\pm$ 12.4	162.0	$\pm$ 12.6	161.9	$\pm$ 12.4	161.7	$\pm$ 12.5	$<$ 0.001
$n=$ 22	Sitting	86.5	$\pm$ 4.7	86.1	$\pm$ 4.5	86.1	$\pm$ 4.5	86.0	$\pm$ 4.6	$<$ 0.001
TL	Standing	165.7	$\pm$ 9.2	165.3	$\pm$ 9.0	165.4	$\pm$ 8.9	165.3	$\pm$ 9.1	$<$ 0.001
$n=$ 35	Sitting	84.5	$\pm$ 7.1	83.9	$\pm$ 7.3	83.8	$\pm$ 7.1	83.8	$\pm$ 7.0	$<$ 0.001
L	Standing	164.7	$\pm$ 13.2	164.1	$\pm$ 13.3	164.2	$\pm$ 13.3	163.9	$\pm$ 13.3	$<$ 0.001
$n=$ 20	Sitting	86.4	$\pm$ 6.3	86.1	$\pm$ 6.4	85.9	$\pm$ 6.4	86.1	$\pm$ 6.4	0.9
DTL	Standing	165.2	$\pm$ 8.5	164.5	$\pm$ 8.6	164.2	$\pm$ 8.5	164.1	$\pm$ 8.5	$<$ 0.001
$n=$ 21	Sitting	85.9	$\pm$ 4.8	85.5	$\pm$ 4.8	85.2	$\pm$ 4.7	85.0	$\pm$ 4.7	$<$ 0.001

Note: significant differences in repeated measures ANOVA are marked in bold; post hoc Tukey test for T: standing and sitting M1 $>$ M2, M3 M4 ( $p<$ 0.001); for TL: standing and sitting M1 $>$ M2, M3 M4 ( $p=$ 0.01, $p=$ 0.04, $p<$ 0.01 for standing, $p=$ 0.01, $p<$ 0.01, $p<$ 0.001 for sitting, respectively); for L: standing M1 $>$ M2, M3 M4 ( $p<$ 0.01, $p<$ 0.01, $p<$ 0.001, respectively); for DTL: standing M1 $>$ M2, M3 M4 ( $p<$ 0.001); M2 $>$ M4 ( $p=$ 0.027); sitting M1 $>$ M2, M3 M4 ( $p=$ 0.017, $p<$ 0.001, $p<$ 0.001, respectively); M2 $>$ M3, M4 ( $p=$ 0.03, $p<$ 0.001, respectively).

4. Discussion

We present the diurnal variation of the body height in children with IS. This topic was discussed in the literature only once in 1983 on 38 Scandinavian patients [21].

Our study revealed, that both in standing and sitting BH significantly decreased during daytime.

The biggest height loss was observed between the measurements performed immediately after getting up (7:00–8:00) and measurements carried out in the evening (19:00–20:00). For both standing and sitting, the mean height loss was 0.7 cm ( $\pm$ 0.7). It is also worth emphasizing that significant differences were noted between height measured in the morning and all the other measurements (both for standing and sitting). On the other hand, the differences between other measurements were not significant (apart from M2 vs. M4 in standing). It suggests that the highest loss of height is observed in the first hours after getting up.

In our opinion, the findings of the study have clinical relevance as the observed mean height loss was higher than the mean measurement error (0.40 cm and 0.28 cm for standing and sitting, respectively). The mean decrease in BH between the measurements performed in the morning and in the evening was bigger than the accuracy of the stadiometer or the standard error for a single measurement of BH. Additionally, for 19 subjects in standing and for 17 subjects in sitting, the loss of body height was higher than 1.0 cm. It indicates, that the diurnal height changes may considerably exceed the mean results (0.7 cm $\pm$ 0.7 for standing, 0.7 cm $\pm$ 0.7 for sitting). It shows that the diurnal height changes may differ for each scoliotic patient, and they should be analyzed individually. In consequence, the study has an impact on clinical practice and indicates that evaluation of BH should be performed at the same time of the day in order to avoid the risk of errors in the evaluation of the growth. However, the authors’ experience indicates that it may be difficult in everyday clinical practice. Thus, we suggest that if height measurement cannot be performed at the same time of the day, the hour of the measurement should be recorded and taken into account during measurement interpretation.

According to our practice most of the patients are seen in the clinics between late morning and early afternoon. Thus, our observing no significant difference in BH between measurements performed at 11:00–12:00 (M2) and at 15:00–16:00 (M3) would suggest that this interval is a perfect timing for the assessment of BH. However, the real individual differences in BH between M2 and M3 were as follows: for standing (1) no change – 43 subjects, (2) decrease by up to 0.5 cm – 10 subjects, (3) decrease by 0.6–1.0 cm – 8 subjects, (4) decrease by 1.6–2.0 cm – 1 subject, (5) 2.6-3.0 cm – 1 subject, (6) increase by up to 0.5 cm – 19 subjects, (7) increase by 0.6–1.0 cm – 9 subjects, (8) increase by 1.1–1.5 cm – 6 subjects, (9) 2.1–2.5 cm – 1 subject; for sitting (1) no change – 38 subjects, (2) decrease by up to 0.5 cm – 11 subjects, (3) decrease by 0.6–1.0 cm – 5 subjects, (4) decrease by 1.1–1.5 cm – 1 subject, (5) increase by up to 0.5 cm – 27 subjects, (6) increase by 0.6–1.0 cm – 11 subjects, (7) increase by 1.1–1.5 cm – 4 subjects, (8) 2.1–2.5 cm – 1 subject. These differences in BH suggest that using a consistent time for measurements of BH would be the best option even if the mean difference between M2 and M3 was not significant.

The mean change in height reported for healthy girls during 12-months during the peak height velocity period (between age 10 years 8 month and 11 years 8 month) is 6.8 cm [26]. Thus, the mean monthly growth would be of 0.56 cm. The mean diurnal difference in BH could be negligible for detecting peak high velocity in patients examined with longer time intervals (e.g. 3.4 cm of growth within 6 month interval). However, the individual differences in BH during the day reaching up to 3 cm could be of high significance for detecting the peak height velocity. The real impact of the diurnal variation in BH on the detection of peak height velocity still remains unclear and should be studied in the future.

The mean loss of standing and sitting height (0.7 cm for both positions) accounted 0.43% and 0.79% of initial standing (164.7 cm) and sitting height (85.9 cm). This suggests that a decrease in the length of the trunk is mostly responsible for the decrease in total body height. Our study confirmed the observations made by Zetterberg et al., who revealed a decrease of BH of patients with IS during a day. This authors observed a mean decrease in height of 11.2 mm (0.7% of initial height), and revealed that a major portion (80%) of these changes took place in the spinal column [21]. It is believed that diurnal variation of height may be related to the loss of fluid from the intervertebral discs as a result of loading of the spine during the day [27, 28]. Other potentially related mechanisms might include the compression of intervertebral cartilage and bending vertebral column during the daytime [15].

A strength of our study is including a significantly higher number of scoliotic patients (98 subjects) in comparison to the study by Zetterberg et al. (38 patients) [21], which allowed us to conduct additional analyses. We could assess the relationship between the diurnal variation of the height and the curve type as well as brace treatment. The study revealed mostly the same pattern of diurnal height variation in each type of IS. The diurnal height change was also similar for both treatment method. However, future study of a larger group of patients than ours would make it possible to perform additional subgroup analysis regarding the patterns of diurnal changes in BH.

The study also showed negligible correlation between a decrease in BH and the magnitude of scoliosis. However, further studies in this area would be valuable, as our study included mostly children with mild and moderate scoliosis and the pattern of diurnal changes of height in subjects with severe scoliosis might be different.

A potential limitation of our research may be that we analyzed children and adolescents with IS regardless the type of IS according to the age of its onset (infantile, juvenile or adolescent). However, diurnal variation of body height in healthy children was also studied in a population with a wide range of ages [15]. Since our analysis revealed negligible correlation between the age of the patient with IS and the diurnal change of body height, we think that the range of age in our study group is not an important limitation of the analysis. It would be also interesting and useful in clinical practice if future studies could answer the question how much time after getting up and for how long body height remains unchanged.

A strength of the research is also the fact, that we have measured the height four times a day (Zetterberg et al. [21] evaluated height twice a day), which allowed us to reveal that the major portion of height loss occurred in first hours after getting up.

There are few studies which assessed diurnal variability of height in healthy children. In the study carried out by Siklar et al. (2005) a reduction in height of nearly 0.5 cm was observed between measurement performed at 9:00–10:00 and 15:00–16:00 [15]. Ashizawa and Kawabata (1990) revealed that the stature shortened by 10 mm within one day [29]. The authors suggested that the main reason for diurnal height change is the shortening of the trunk length during the day. Rodriguez et al. (2000) also observed that height at 20:00 decreased by 1.15 cm compared to 08:00 [30]. Voss and Bailey (1997) confirmed both diurnal variation and a greater proportion of the height loss during an earlier part of the day. Over the period between 09:00 and 15:00 the authors found an average decrease of 0.5 cm, though several children lost over 1 cm [14].

These data suggest that the diurnal loss of body height in IS patients is similar to that reported for healthy children. Therefore, the pattern of diurnal height decreases appears not to be related to IS, but is a phenomenon typical for children and adolescents.

5. Conclusions

Body height decreases in children and adolescents with IS during daytime.

The height change occurs mostly in the spine and is not related to the curve type or magnitude of IS.

Brace treatment does not have a large influence the pattern of diurnal body height loss.

Due to diurnal body height variation, we suggest recording the time of the day when measuring height in patients with IS.

Footnotes

Conflict of interest

The authors declare that they have no conflict of interest.

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Diurnal variation of body height in children with idiopathic scoliosis

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Material and methods

2.1 Material

2.2 Methods

Table 1 Mean values of body height measured in standing and sitting during each of 4 periods of the day

3. Results

3.1 Pilot reliability study

3.2 Diurnal changes in body height – whole group

3.4 Diurnal changes in body height – the influence of the curve type in IS

Table 4 The comparison of the mean height loss observed in children with and without brace for each comparison interval

5. Conclusions

Footnotes

Conflict of interest

References

Table 1
Mean values of body height measured in standing and sitting during each of 4 periods of the day

Table 4
The comparison of the mean height loss observed in children with and without brace for each comparison interval