Table 3 Study characteristics, reliability, validity and SEM data of included studies

Biophotogrammetric analysis

Milanesi 2011 [25]

Cervical and lumbar lordosis apex arrows

24 adults with clinical manifestation of mouth breathing during childhood

18–30 years

3 raters on 1 occasion

Inter-rater

ICC

> 0.75

0.23−0.37 cm (range)

Zheng 2010 [30]

C7-S1 offset

30 asymptomatic adult participants

35.5 ± 9.4 years

Examined 12 times in neutral standing and hands on clavicles

Intra-rater

Repeatability (mean of the SD ± SD)

6 ± 1.9 mm neutral standing

As above

7.3 ± 3 mm hands on clavicles

Freepoint (FP) ultrasound system

Zabjeck 1999 [28]

T1-S1 offset

15 adult control participants

25 ± 6 years

Examined 5 times by each system 1 week apart

FP intra-session

Mean ± SD

19.1 ± 7.9 mm

2.03 mm (mean)

FP inter-session

difference

Mean ± SD

−3.2 ± 11.6 mm

2.99 mm (mean)

MA vs. freepoint

ICC

0.93

Infra-red motion analysis

de Seze 2015 [21] Elite IR optoelectronic system

C7-S1 offset

43 adults with camptocormia

69 ± 10 years

Validity. Radiographic sagittal vertical axis

(SVA)

ICC

0.83

Negrini 2001. [26] Auscan optoelectronic 3D IR imaging system with manual landmark identification

C7-S1 offset

97 patients with adolescent idiopathic scoliosis

15.15 ± 2.25 years

Examined twice with 3 time intervals between measurements

Intra-session 6 s interval

Bland and Altman repeatability coefficient

12.52 mm (mean difference)

Intra-session 24 s interval

As above

14.64 mm (as above)

Intra-session 167 s interval

As above

22.94 mm (as above)

Zabjeck 1999 [28]

IR motion analysis (MA) system and freepoint (FP) ultrasound system

T1-S1 offset

15 adult control participants

25 ± 6 years

Examined 5 times by each system 1 week apart

MA intra-session difference

Mean ± SD

10.9 ± 7 mm

1.8 mm (mean)

MA inter-session difference

Mean ± SD

2.9 ± 6.9 mm

1.78 mm (mean)

Plumbline testing

de Seze 2015 [21]

C7-S1 Sagittal arrows

43 adults with camptocormia

69 ± 10 years

Validity.

Radiographic sagittal vertical axis

(SVA)

ICC

0.81

Grosso 2002 [31]

C7-L3 sagittal arrows

116 AIS, hyperkyphotic and hyperlordotic adolescents

13.6 ± 2.4 years

2 raters on 2 occasions

Inter-rater

ICC cervical

0.86

ICC lumbar

0.76

Zaina 2012 [29]

C7 and L3 Sagittal arrows

180 AIS and hyperkyphotic adolescents

Aged 11–16

Examined by 2 raters and then repeated after 5 min by one rater

Intra-rater

Bland and Altman repeatability coefficient

0.9 mm C7

1.2 mm L3 (mean difference)

Inter-rater

As above

1.7 mm C7

2.2 mm L3

Spinal mouse

Kellis 2008 [23]

C7-S1 Angular

trunk inclination

81 healthy children

10.6 ± 1.7 years

Examined by 3 raters on 2 separate occasions

Intra-rater

ICC

0.67–0.87

1.19°–1.97°

(range)

Inter-rater

ICC

0.77–0.82

0.96°–1.2°

Mannion 2004 [24]

C7-S1 Angular

trunk inclination

29 healthy adult participants

45.4 ± 7.7 years

Examined by 2 raters on 2 separate occasions

Intra-rater

ICC

0.83–0.84

1° (0.8°–1.5)° (mean)(95% CI)

Inter-rater

ICC

0.71–0.77

1.5° (1.2–2.2 95% CI)

(as above)

Surface topography

Knott 2016 [22] Diers formetric surface topography system compared with upright full spine radiographs

VP-DM sagittal trunk inclincation. Compared with C7-S1 trunk inclination

193 AIS and hyperkyphotic adolescents

8–18 years

Multicentre trial with same day testing.

Validity. Radiographic sagittal vertical inclination

Pearson’s Correlation

0.49

± 3.7° (SD)

Three scans repeated within 5 min

ICC

0.91

± 1.1° (SD)

Legaye 2012 [13]. Biomod surface topographical system with manual landmark identification

C7 and superior border of gluteal cleft angular trunk inclination

1 symptomatic male, 1 asymptomatic scoliotic female participant

Both 53-year olds

Examined once by 5 raters (inter-observer) and 15 times by one rater (intra-observer).

Intra-rater

Confidence interval

1°

Inter-rater

Confidence interval

1°

C7 and superior border of -gluteal cleft (pelvic) sagittal arrows

As above

Intra-rater

Confidence interval

3 mm cervical

Confidence interval

5 mm pelvic

Inter-rater

Confidence interval

4 mm cervical

Confidence interval

4 mm pelvic

C7 and superior border of -gluteal cleft Angular

trunk inclination

326 adults with pain or deformity(kyphosis, fractures, scoliosis)

Range from 7 to 86 years

Correlation between radiographs and surface topography

Validity. Radiographic C7S1 angular axis

Pearson’s correlation

R = 0.68 p < 0.001

Liljenqvist 1998 [19] Diers formetric surface topography system compared with upright full spine radiographs

VP-DM sagittal offset distance

95 children, adolescents and adult patients with scoliosis or hyperkyphosis

Mean age 16.5 range 7–30 years

Correlation between radiographs and surface topography examined by 2 raters

Validity.

Radiographic sagittal vertical axis (SVA)

Root mean square deviation

1.07 cm

Mohokum [20] 2010Diers formetric surface topography system with automatic landmark identification

VP-DM sagittal offset distance^a

51 healthy adults with normal and high BMI

24.6 ± 5.8 years

Examined 3 times by 3 raters on one occasion

3.49 mm (mean)

Intra-rater

Cronbach α

0.950–0.985

Inter-rater

Cronbach α

0.97

Schroeder [27] 2015Diers formetric surface topography system with automatic landmark identification

VP-DM sagittal offset distance

20 adult participants without back pain

25.4 ± 5.5 years

Within 5 min on 1 day, the following day and the following week

3 mm (mean)

Intra-day

ICC

0.858–0.978

Inter-day

ICC

0.843–0.977

Inter-week

ICC

0.855–0.977