Table 4 Rating of reported validity and reliability for foot posture measures and definition of flexible flat foot in paediatric populations

Plain film radiograph angles

Calcaneal pitch

[33, 53]

<  20°

4–6 & 8–13

Nil

Nil

No/No

[38]

<  23°

4–18

Nil

Nil

No/No

[31]

≤ 15.4°

7–12

NR [57]

Nil

No/No

AP talocalcaneal

[53]

>  25°

4–6

Nil

Nil

No/No

[33]

>  30°

8–13

Nil

Nil

No/No

Plantarflexion of talus

[53]

>  23°

4–6

Nil

Nil

No/No

Lateral talocalcaneal

[33]

>  45°

8–13

Nil

Nil

No/No

Calcaneal first metatarsal

[38]

145°-170°

4–18

Nil

Nil

No/No

Talus-first metatarsal

[33] [31]

>  4°

7–13

Nil

NR [80], NA [64]

No/No

Foot print indices

Arch index

[35, 54], [36]

≥ 0.26

3–6, 5–13, 4–14

Nil

Nil

No/No

[37]

≥ 0.26

10

NR [58]

Substantial [81], NR [37]

No/Yes

[30, 32, 42]

>  0.26

6–13

Nil

Nil

No/No

Chippaux-Smirak

[46]

≥ 59%

6–9

Nil

Excellent [46]

No/Yes

[34]

>  62.7%

3–7

Moderate [34]

NR [65]

With caution/No

[56]

>  62.7%

3–7

Moderate [34]

Nil

With caution/No

[37],

≥ 45%

10

NR [59]

NR [37]

No/No

[40]

≥ 45%

3–17

Nil

Nil

No/No

[31]

≥ 40%

9–16

Moderate [31]

NR [60]

Nil

With caution/No

Clarke’s angle

[34]

≤ 14.04

3–6

Moderate [34]

Nil

With caution/No

[37]

≤ 20°

10

Nil

NR [37, 59]

No/No

[38]

<  42°

9–16

Excellent [38]

Nil

With caution/No

[55]

<  42°

4–18

Nil

Nil

No/No

[31]

<  29.9°

9–16

Moderate [31],NR [60]

Nil

With caution/No

Staheli arch index

[46]

≥ 1.28

6–9

Nil

Excellent [46]

No/Yes

[34]

>  1.07

3–6

Moderate [34]

NR [65]

With caution/No

[48]

>  1.15

6–10

NR [59, 61]

Nil

No/No

[52]

>  0.89

10–12

Nil

Nil

No/No

Footprint index

[42]

<  0.25

9–12

Nil

Nil

No/No

Martirosov’s K index

[37]

≥ 1.25

10

Nil

NR [37]

No/No

Footprint evaluation

[51]

X > Y

6–17

Nil

NR [66]

No/No

Instep

[45]

100 mm

6–12

Nil

Nil

No/No

Plantar footprint

[49]

≥ 50%

4–13

Nil

Nil

No/No

Static foot measures

Rearfoot eversion

[53]

>  10°

4–6

Nil

Nil

No/No

[33]

≥ 4°

8–13

Nil

Nil

No/No

[47]

≥ 4°

6–13

Nil

NA [67]

No/No

[55]

>  5°

4–18

Nil

Nil

No/No

[39]

>  5°

3–6

Nil

NR [68]

No/No

[41]

> (7° - age)

3–6

Nil

Substantial [41]

No/Yes

Arch Height Index

[47]

≤ 0.37

6–13

NR [62]

Substantial [47]NR [82, 83]

No/Yes

[50]

<  0.31

8–15

Nil

Nil

No/No

FPI-6

[29]

≥ + 6

3–15

Not rated^ [63]

Substantial [69]

With caution/Yes

[28]

≥ + 4

6–11

Nil

Excellent [70]

No/Yes

Navicular height

[42]

<  20 mm

9–12

Nil

Nil

No/No

Other measures

Plantar pressure analysis (FGP)

[53]

54%

4–6

Nil

Nil

No/No