Table 2 Characteristics of the groups, number (%), mean (SD), median (IQR), of demographics, ranges of motion and strength measures (Normative data versus ITW data)

Age (years)

6.9 (2.0), 4 to 10

6.3 (1.8), 4 to 10

−0.18 [− 0.40, 0.05] 0.127

Sex (male)

68 (50%)

17 (65%)

−0.64 [−1.2, 0.24] 0.154

Height (m)

1.3 (0.1), 0.9 to 1.6

1.2 (0.1), 1.0 to 1.5

−4.19 [−7.59, − 0.80] 0.016

Weight (kg)

27.6 (8.8), 14.1 to 54.2

24.0 (6.6), 15.0 to 40.0

−0.06 [− 0.12, 0.01] 0.056

 Hip internal

41.3 (8.6), 20 to 67

37.4 (14.4), 15 to 70

−0.04 [− 0.09, 0.01] 0.064

 Hip external

35.2 (11.8), 9 to 65

31.6 (8.5), 16 to 65.5

0.04 [−0.01, 0.08] 0.074

 Hip flexion

132.4 (9.7), 106 to 160.5

131.5 (16.2), 80 to 157

− 0.01 [− 0.05, 0.03] 0.708

 Knee extension

3.4 (3.4), −5.5 to 14.5

2.9 (9.2), −18 to 25

− 0.02[− 0.11, 0.07] 0.620

 Knee flexion

144.8 (5.6), 129 to 156.5

146.0 (6.8), 134 to 162

0.03 [−0.04, 0.11] 0.354

 Ankle plantarflexion

62.6 (8.1), 33.5 to 85.0

57.9 (12.3), 35 to 80

−0.05 [− 0.10, − 0.01] 0.018

 Ankle dorsiflexion (straight leg)

32.8 (4.4), 26.1 to 43.2^a

26.3 (10.5), 2.3 to 45.9

−0.12 [− 0.21, − 0.03] 0.009

 Ankle dorsiflexion (bent knee)

32.9 (7.1), 16 to 49

29.1 (10.7), 5.5 to 50.5

− 0.06 [− 0.12, − 0.01] 0.029

 Hip internal rotation

73.0 (29.7), 20 to 168

49.6 (21.8), 11 to 93

−0.04 [− 0.06, − 0.02] < 0.001

 Hip external rotation

54.1 (20.4), 12 to 111

44.6 (19.6), 7 to 84

− 0.03 [− 0.05, − 0.01] 0.027

 Hip abduction

61.5 (17.3), 8 to 77

40.1 (24.1), 20 to 127

− 0.05 [− 0.07, − 0.02] < 0.001

 Knee extension

127.1 (43.2), 45 to 265

81.9 (29.2), 27 to 133

− 0.04 [0.05, − 0.02] < 0.001

 Knee flexion

95.2 (32.4), 25 to 212

70.1 (32.4), 14 to 176

− 0.03 [− 0.05, − 0.01] 0.001

 Ankle dorsiflexion

96.9 (34.5), 24 to 203

61.1 (34.7), 11 to 158

− 0.04 [− 0.06, 0.02] < 0.001

 Ankle plantarflexion

164.7 (49.7), 66 to 285

72.3 (35.5), 12 to 177

−0.06 [0.08, − 0.04] < 0.001