Background
Methods
Participants
Preparation of the foot and marking of the skin measurement sites
Skin surface hydration measurement
Skin elasticity measurement
Collagen and elastin fibre organisation measurement
Surface evaluation of living skin (SELs)
Heel fissure depth measurement
Measurement of room temperature and humidity
Statistical analysis
Results
Bland - Altman data | ||||||
---|---|---|---|---|---|---|
ICC agreement | 95 % CI | SEM consistency | Mean difference [SD] | 95 % LOA | ||
Investigator A
| ||||||
Callus
|
Hydration [AU]
| 0.61 | −0.95 - 0.93 | 0.26 | −1.25 [3.11] | −7.30 – 4.80 |
Elasticity [mm]
| 0.77 | −0.17 - 0.97 | 0.06 | 0.30 [0.40] | −0.47 – 1.08 | |
Collagen and elastin fibre organisation [AU]
| 0.98 | 0.88 - 1.00 | 6.76 | 1.69 [44.50] | −85.50 – 88.92 | |
SEsm [AU]
| 0.88 | 0.34 – 0.98 | 1.23 | −0.61 [24.76] | −49.13 – 47.91 | |
SEr [AU]
| 0.84 | 0.10 – 0.97 | 0.29 | −0.10 [1.74] | −3.51 – 3.31 | |
SEsc [AU]
| 0.38 | 0.84 – 1.51 | 0.03 | −0.20 [0.38] | −0.94 – 0.55 | |
Heel fissure
|
Hydration [AU]
| 0.93 | 0.26 – 0.99 | 0.35 | 0.26 [2.33] | −4.30 – 4.82 |
Elasticity [mm]
| 0.82 | −4.42 – 1.00 | 0.00 | 0.03 [0.10] | −0.16 – 0.21 | |
SEsm [AU]
| 1.00 | 8.85 – 0.90 | 0.00 | −11.35 [33.12] | −76.27 – 53.57 | |
SEr [AU]
| 0.38 | 0.97 – 6.14 | 1.24 | −0.20 [2.47] | −5.03 – 4.63 | |
SEsc [AU]
| 0.73 | 0.98 – 21.89 | 0.04 | −0.07 [0.12] | −0.29 – 0.16 | |
Fissure depth [μm] | 0.95 | 0.46 – 1.00 | 4.83 | −20.08 [29.74] | −78.37 – 38.21 | |
Xerotic plantar heel skin
|
Hydration [AU]
| 0.88 | −0.49 – 1.00 | 0.37 | 0.59 [2.05] | −3.43 – 4.61 |
Elasticity [mm]
| 0.53 | −9.25 – 0.97 | 0.01 | −0.05 [0.11] | −0.25 – 0.16 | |
Collagen and elastin fibre organisation [AU]
| 0.98 | 0.33 – 1.00 | 0.51 | −12.58 [8.37] | −28.98 – 3.83 | |
SEsm [AU]
| 0.51 | 0.46 – 0.96 | 14.13 | −27.07 [20.70] | −67.64 – 13.51 | |
SEr [AU]
| 0.68 | 0.82 – 2.17 | 0.17 | −0.71 [0.84] | −2.35 – 0.94 | |
SEsc [AU]
| 0.31 | 0.93 – 7.56 | 0.41 | 0.33 [0.59] | −0.82 – 1.47 | |
PMA
|
Hydration [AU]
| 0.97 | 0.86 – 1.00 | 0.16 | −0.35 [2.64] | −5.50 – 4.82 |
Elasticity [mm]
| 0.45 | −2.68 – 0.92 | 7.9 x10−5 | 0.08 [0.19] | −0.31 – 0.46 | |
Collagen and elastin fibre organisation [AU]
| 0.88 | 0.32 – 0.98 | 32.02 | 18.06 [95.33] | −168.80 – 204.90 | |
SEsm [AU]
| 0.96 | 0.84 – 0.99 | 0.07 | −0.61 [10.65] | −21.48 – 20.26 | |
SEr [AU]
| 0.76 | 0.06 – 0.94 | 0.48 | −0.24 [2.06] | −4.28 – 3.79 | |
SEsc [AU]
| 0.78 | 0.14 – 0.94 | 0.08 | −0.07 [0.64] | −1.32 – 1.18 | |
5th met. base
|
Hydration [AU]
| 0.92 | 0.73 – 0.98 | 0.15 | −1.10 [2.77] | −6.51 – 4.32 |
Elasticity [mm]
| 0.80 | 0.11 – 0.95 | 0.34 | −0.02 [0.16] | −0.33 – 0.30 | |
Collagen and elastin fibre organisation [AU]
| 0.98 | 0.92 – 1.00 | 4.16 | 1.61 [36.50] | −69.92 – 73.14 | |
SEsm [AU]
| 0.72 | 0.24 – 0.90 | 0.44 | −4.18 [22.91] | −49.09 – 40.73 | |
SEr [AU]
| 0.66 | 0.03 – 0.88 | 0.31 | 0.11 [1.16] | −2.17 – 2.38 | |
SEsc [AU]
| 0.72 | 0.23 – 0.90 | 0.49 | 0.17 [1.21] | −2.20 – 2.53 | |
Bland – Altman data
| ||||||
ICC agreement
|
95 % CI
|
SEM consistency
|
Mean difference [SD]
|
95 % LOA
| ||
Investigator B
| ||||||
Callus
|
Hydration [AU]
| 0.40 | −3.17 – 0.90 | 0.73 | −0.99 [3.67] | −8.18 – 6.19 |
Elasticity [mm]
| 0.98 | 0.82 – 1.00 | 0.02 | 0.01 [0.17] | −0.34 – 0.35 | |
Collagen and elastin fibre organisation [AU]
| 1.00 | 0.92 – 1.00 | 5.62 | 18.87 [46.12] | −71.54 – 109.30 | |
SEsm [AU]
| 0.82 | 0.11 – 0.96 | 0.34 | 4.97 [22.52] | −39.17 – 49.11 | |
SEr [AU]
| 0.84 | 0.19 – 0.97 | 0.43 | 0.40 [1.99] | −3.50 – 4.30 | |
SEsc [AU]
| 0.89 | 0.02 | −0.15 [0.24] | −0.61 – 0.31 | ||
Heel fissure
|
Hydration [AU]
| 0.89 | −0.28 – 1.00 | 0.94 | 0.29 [3.21] | −6.01 – 6.60 |
Elasticity [mm]
| 0.95 | −0.05 – 1.00 | 0.00 | −0.06 [0.02] | −0.10 – 0.01 | |
SEsm [AU]
| 0.68 | 0.94 – 5.03 | 12.62 | 4.97 [22.52] | −39.17 – 49.11 | |
SEr [AU]
| 0.67 | 0.98 – 32.45 | 1.21 | 0.44 [2.29] | −4.05 – 4.94 | |
SEsc [AU]
| 0.61 | 0.98 – 20.97 | 0.02 | 0.06 [0.17] | −0.28 – 0.39 | |
Fissure depth [μm] | 0.64 | 0.47 – 0.93 | 49.90 | 5.56 [14.06] | −270.10 – 281.20 | |
Xerotic plantar heel skin
|
Hydration [AU]
| 0.84 | −0.52 – 0.98 | 0.64 | 0.68 [2.40] | −4.03 – 5.38 |
Elasticity [mm]
| 0.40 | 7.74 – 0.96 | 0.01 | −0.18 [0.07] | −0.15 – 0.12 | |
Collagen and elastin fibre organisation [AU]
| 0.86 | −0.19 – 0.99 | 6.55 | −16.98 [19.34] | −54.88 – 20.93 | |
SEsm [AU]
| 0.76 | 0.71 – 0.98 | 8.04 | −15.60 [21.64] | −58.01 – 26.82 | |
SEr [AU]
| 0.37 | 0.66 – 0.94 | 0.05 | −0.64 [0.58] | −1.77 – 0.49 | |
SEsc [AU]
| 0.86 | 0.22 – 0.99 | 0.06 | 0.11 [0.19] | −0.26 – 0.48 | |
PMA
|
Hydration [AU]
| 1.00 | 0.89 – 1.00 | 0.00 | −1.43 [1.92] | −5.20 – 2.33 |
Elasticity [mm]
| 0.55 | −6.05 – 0.94 | 0.04 | 0.00 [0.15] | −3.00 – 0.30 | |
Collagen and elastin fibre organisation [AU]
| 0.96 | 0.75 – 0.99 | 5.42 | −5.96 [37.55] | −79.56 – 67.64 | |
SEsm [AU]
| 0.95 | 0.81 – 0.99 | 1.46 | 5.33 [11.50] | −17.21 – 27.87 | |
SEr [AU]
| 0.89 | 0.58 – 0.97 | 0.09 | −0.05 [1.04] | −2.10 – 1.98 | |
SEsc [AU]
| 0.89 | 0.59 – 0.97 | 0.28 | −0.21 [0.42] | −1.02 – 0.61 | |
5th met. base
|
Hydration [AU]
| 0.91 | 0.72 – 0.98 | 0.16 | −1.20 [3.90] | −8.85 – 6.45 |
Elasticity [mm]
| 0.54 | −0.45 – 0.88 | 0.03 | 0.05 [0.10] | −0.14 – 0.25 | |
Collagen and elastin fibre organisation [AU]
| 0.99 | 0.95 – 1.00 | 3.17 | −65.61 [88.91] | −65.61 – 88.91 | |
SEsm [AU]
| 0.92 | 0.78 – 0.97 | 2.93 | −4.16 [11.29] | −26.30 – 17.97 | |
SEr [AU]
| 0.84 | 0.52 – 0.94 | 0.12 | 0.51 [0.90] | −1.26 – 2.28 | |
SEsc [AU]
| 0.88 | 0.67 – 0.96 | 0.07 | 0.03 [0.48] | −0.91 – 0.96 |
Bland - Altman data | ||||||
---|---|---|---|---|---|---|
ICC agreement | 95 % CI | SEM consistency | Mean difference [SD] | 95 % LOA | ||
Day 1
| ||||||
Callus
|
Hydration [AU]
| 0.89 | 0.30 – 0.98 | 0.08 | −0.14 [2.20] | −4.45 – 4.18 |
Elasticity [mm]
| 0.83 | −0.01 – 0.98 | 0.01 | 0.31 [0.37] | −0.41 – 1.03 | |
Collagen and elastin fibre organisation [AU]
| 1.00 | 0.74 – 0.99 | 0.00 | −45.10 [66.09] | −174.6 – 84.44 | |
SEsm [AU]
| 0.91 | 0.59 – 0.98 | 1.54 | −5.42 [18.15] | −41.00 – 30.16 | |
SEr [AU]
| 0.62 | 0.93 – 1.23 | 0.32 | −0.47 [3.03] | −6.41 – 5.46 | |
SEsc [AU]
| 0.87 | 0.31 – 0.97 | 0.02 | −0.02 [0.20] | −0.42 – 0.38 | |
Heel fissure
|
Hydration [AU]
| 0.98 | 0.82 – 1.00 | 0.17 | −0.77 [1.64] | −3.97 – 2.44 |
Elasticity [mm]
| 0.78 | −0.34 – 0.98 | 0.01 | 0.11 [0.08] | −0.05 – 0.27 | |
SEsm [AU]
| 0.92 | 0.24 – 1.00 | 0.30 | −9.83 [12.66] | −34.63 – 4.98 | |
SEr [AU]
| 0.90 | 0.01 – 0.99 | 0.16 | −0.41 [0.76] | −1.89 – 1.08 | |
SEsc [AU]
| 0.74 | 0.67 – 0.98 | 0.03 | −0.08 [0.10] | −0.28 – 0.12 | |
Fissure depth [
μm]
| 0.33 | −4.50 – 0.95 | 0.49 | −67.20 [120.10] | −302.80 – 168.20 | |
Xerotic plantar heel skin
|
Hydration [AU]
| 0.97 | 0.79 – 1.00 | 0.05 | −0.40 [1.23] | −2.81 – 2.00 |
Elasticity [mm]
| 0.86 | −0.32 – 0.99 | 0.02 | 0.03 [0.06] | −0.08 – 0.14 | |
Collagen and elastin fibre organisation [AU]
| 0.95 | 0.26 – 1.00 | 3.05 | 16.05 [14.68] | −12.71 – 44.81 | |
SEsm [AU]
| 0.96 | 0.03 – 1.00 | 0.68 | −12.01 [6.53] | −24.82 – 0.79 | |
SEr [AU]
| 0.29 | 0.96 – 9.93 | 0.12 | −0.19 [0.73] | −1.62 – 1.25 | |
SEsc [AU]
| 0.83 | 0.56 – 0.99 | 0.10 | 0.20 [0.36] | −0.51 – 0.91 | |
PMA
|
Hydration [AU]
| 1.00 | 0.97 – 1.00 | 0.00 | −0.48 [1.26] | −2.95 – 1.99 |
Elasticity [mm]
| 0.69 | −0.19 – 0.95 | 0.00 | 0.19 [0.09] | 0.01 – 0.36 | |
Collagen and elastin fibre organisation [AU]
| 0.90 | 0.48 – 0.98 | 25.46 | 38.30 [87.57] | −133.30 – 209.90 | |
SEsm [AU]
| 0.97 | 0.70 – 0.99 | 0.92 | −7.34 [7.68] | −22.39 – 7.71 | |
SEr [AU]
| 0.86 | 0.46 – 0.96 | 0.37 | −0.09 [1.65] | −3.31 – 3.14 | |
SEsc [AU]
| 0.84 | 0.44 – 0.96 | 0.04 | 0.10 [0.44] | −0.76 – 0.96 | |
5th met. base
|
Hydration [AU]
| 0.97 | 0.88 – 0.99 | 0.21 | −0.89 [2.18] | −5.16 – 3.38 |
Elasticity [mm]
| 0.74 | 0.00 – 0.93 | 0.06 | 0.11 [0.14] | −0.17 – 0.39 | |
Collagen and elastin fibre organisation [AU]
| 0.96 | 0.84 – 0.99 | 8.83 | −31.32 [58.35] | −145.70 – 83.04 | |
SEsm [AU]
| 0.82 | 0.50 – 0.94 | 1.74 | 0.19 [17.45] | −34.02 – 34.40 | |
SEr [AU]
| 0.65 | 0.07 – 0.87 | 0.37 | −0.34 [1.21] | −2.70 – 2.03 | |
SEsc [AU]
| 0.84 | 0.58 – 0.94 | 0.34 | 0.29 [0.94] | −1.56 – 2.14 | |
Bland – Altman data
| ||||||
ICC agreement
|
95 % CI
|
SEM consistency
|
Mean difference [SD]
|
95 % LOA
| ||
Day 2
| ||||||
Callus
|
Hydration [AU]
| 0.97 | 0.82 – 1.00 | 0.05 | 0.12 [0.97] | −1.78 – 2.02 |
Elasticity [mm]
| 0.99 | 0.99 – 1.00 | 0.00 | 0.02 [0.02] | −0.02 – 0.05 | |
Collagen and elastin fibre organisation [AU]
| 0.97 | 0.82 – 0.99 | 9.51 | −27.92 [51.18] | −128.2 - -72.38 | |
SEsm [AU]
| 0.94 | 0.67 – 0.99 | 9.47 | 0.16 [17.01] | −33.19 – 33.51 | |
SEr [AU]
| 0.98 | 0.88 – 1.00 | 0.18 | 0.03 [0.63] | −1.21 – 1.26 | |
SEsc [AU]
| 0.86 | 0.26 – 0.97 | 0.01 | 0.02 [0.20] | −0.37 – 0.41 | |
Heel fissure
|
Hydration [AU]
| 0.97 | 0.72 – 1.00 | 0.06 | −0.74 [1.07] | −2.80 – 1.37 |
Elasticity [mm]
| 0.89 | −0.42 – 0.99 | 0.00 | 0.03 [0.08] | −0.12 – 0.18 | |
SEsm [AU]
| 0.78 | 0.99 – 102.52 | 5.48 | −0.45 [6.92] | −14.01 – 13.11 | |
SEr [AU]
| 0.99 | 0.93 – 1.00 | 0.14 | 0.24 [0.41] | −0.57 – 1.04 | |
SEsc [AU]
| 0.95 | 0.10 – 1.00 | 0.01 | −0.01 [0.08] | −0.17 – 0.15 | |
Fissure depth [
μm]
| 0.82 | −0.35 – 0.99 | 13.71 | −41.65 [44.17] | −128.20 – 44.92 | |
Xerotic plantar heel skin
|
Hydration [AU]
| 0.95 | 0.57 – 1.00 | 0.06 | −0.32 [1.09] | −2.46 – 1.82 |
Elasticity [mm]
| 0.69 | −0.51 – 0.98 | 0.02 | 0.06 [0.06] | −0.05 – 0.17 | |
Collagen and elastin fibre organisation [AU]
| 0.85 | −0.97 – 0.99 | 10.66 | 11.65 [29.32] | −45.82 –69.12 | |
SEsm [AU]
| 0.91 | 0.99 – 1.26 | 7.15 | −0.54 [8.75] | −17.70 – 16.61 | |
SEr [AU]
| 0.76 | 0.98 – 4.99 | 0.21 | −0.12 [0.41] | −0.93 – 0.68 | |
SEsc [AU]
| 0.75 | 0.99 – 27.38 | 0.10 | −0.01 [0.14] | −0.29 – 0.27 | |
PMA
|
Hydration [AU]
| 0.97 | 0.83 – 1.00 | 0.37 | −1.56 [2.80] | −7.05 – 3.93 |
Elasticity [mm]
| 0.70 | −0.34 – 0.95 | 0.04 | 0.11 [0.11] | −0.10 – 0.32 | |
Collagen and elastin fibre organisation [AU]
| 0.96 | 0.79 – 0.99 | 3.03 | 14.29 [31.34] | 47.15 –75.72 | |
SEsm [AU]
| 0.99 | 0.97 – 1.00 | 0.92 | −1.41 [4.17] | −9.58 – 6.77 | |
SEr [AU]
| 0.91 | 0.67 – 0.98 | 0.28 | 0.11 [0.94] | −1.74 – 1.95 | |
SEsc [AU]
| 0.99 | 0.97 – 1.00 | 0.01 | −0.03 [0.15] | −0.33 – 0.27 | |
5th met. base
|
Hydration [AU]
| 0.93 | 0.77 – 0.98 | 0.61 | −1.00 [3.11] | −7.09 – 5.09 |
Elasticity [mm]
| 0.38 | −0.22 – 0.80 | 0.05 | 0.18 [0.10] | −0.01 – 0.38 | |
Collagen and elastin fibre organisation [AU]
| 0.97 | 0.87 – 0.99 | 5.70 | −21.28 [43.27] | −1.06.10 – 63.52 | |
SEsm [AU]
| 0.92 | 0.79 – 0.97 | 2.01 | 0.21 [13.05] | −25.38 – 25.80 | |
SEr [AU]
| 0.71 | 0.19 – 1.00 | 0.20 | 0.07 [1.22] | −2.30 – 2.47 | |
SEsc [AU]
| 0.93 | 0.80 – 1.00 | 0.13 | 0.15 [0.32] | −0.48 – 0.78 |