| Literature DB >> 25364389 |
Yu-Chi Lee1, Gloria Lin1, Mao-Jiun J Wang1.
Abstract
BACKGROUND: Foot dimension information on different user groups is important for footwear design and clinical applications. Foot dimension data collected using different measurement methods presents accuracy problems. This study compared the precision and accuracy of the 3D foot scanning method with conventional foot dimension measurement methods including the digital caliper, ink footprint and digital footprint.Entities:
Year: 2014 PMID: 25364389 PMCID: PMC4215017 DOI: 10.1186/s13047-014-0044-7
Source DB: PubMed Journal: J Foot Ankle Res ISSN: 1757-1146 Impact factor: 2.303
Definition of the six foot dimensions
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| 1. Foot length | The direct distance from pternion point to the most anterior point of the longest toe (first or second) measured parallel to the foot axis. |
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| 2. Ball of foot length | The distance from the end of heel to the metatarsal tibial measured parallel to the foot axis. | |
| 3. Outside ball of foot length | The distance from the end of heel to the metatarsal fibular measured parallel to the foot axis. | |
| 4. Foot breadth diagonal | The distance between the metatarsal tibial and metatarsal fibular of the ball cross section projected to the standing surface. |
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| 5. Foot breadth horizontal | The horizontal distance between metatarsal tibial to metatarsal fibular. | |
| 6. Heel breadth | The breadth of position at 16% foot length straight from the pternion point to toe. |
Foot axis: The line passes from the pternion to the tip of the second toe.
Figure 1The four measurement methods: digital caliper (a), 3D foot scanner (b), Harris mat (c) and digital footprint image (d).
Summary of two-way ANOVA results
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| Sex | 1 | *** | *** | *** | *** | *** | *** |
| Method | 3 | *** | *** | *** | *** | *** | *** |
| Sex* Method | 3 | NS | NS | NS | NS | NS | NS |
***Significant difference (p < 0.001); NS: no significant difference; d.f.: degree of freedom.
Figure 2The sex differences in six foot dimensions among measuring methods (unit in mm).
ANOVA and Duncan’s MRT results among the four methods
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| 3D scanning | 249.3 (15.7) | A | 181.6 (11.6) | A | 164.1 (10.64) | A | 99.0 (7.3) | A | 97.1 (7.0) | A | 63.2 (4.5) | A |
| Digital caliper | 247.7 (15.7) | A | 177.7 (12.7) | B | 157.0 (10.8) | B | 94.7 (7.2) | B | 85.2 (7.4) | B | 62.6 (4.0) | A |
| Digital footprint | 233.0 (14.8) | B | 170.6 (10.9) | C | 153.4 (9.9) | C | 87.8 (6.4) | C | 86.0 (6.3) | B | 50.1 (3.8) | B |
| Ink footprint | 234.1 (14.6) | B | 172.0 (10.6) | C | 147.7 (9.3) | D | 88.6 (6.5) | C | 85.1 (6.2) | B | 47.7 (3.9) | C |
| p-value | p < 0.001 | p < 0.001 | p < 0.001 | p < 0.001 | p < 0.001 | p < 0.001 | ||||||
Precision evaluation for the four methods
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| Foot length | 1.50 | 1.41 | 1.53 | 1.60 | 3.00 |
| Ball of foot length | 1.36 | 2.40 | 1.46 | 1.80 | 6.00 |
| Outside ball of foot length | 1.34 | 2.01 | 1.41 | 1.90 | |
| Foot breadth diagonal | 0.73 | 1.42 | 0.77 | 2.65 | |
| Foot breadth horizontal | 0.79 | 1.66 | 0.83 | 1.75 | 2.00 |
| Heel breadth | 0.91 | 0.80 | 0.86 | 1.20 | 2.00 |
aMAD between the repeated measurements.
Accuracy evaluation for the four methods
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| Foot length | 1.6 | 14.7 | 13.6 | 2.00 |
| Ball of foot length | 3.9 | 7.1 | 5.7 | 2.00 |
| Outside ball of foot length | 7.1 | 3.6 | 9.3 | 2.00 |
| Foot breadth diagonal | 4.3 | 6.9 | 6.1 | 2.00 |
| Foot breadth horizontal | 11.9 | 0.8 | 0.1 | 2.00 |
| Heel breadth | 0.6 | 12.5 | 14.9 | 2.00 |
aMAD between the digital caliper measurement and the 3D scanning, ink footprint and digital footprint measurement.
The intra-class correlation coefficients (ICC) for the four measurement methods
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| Foot length | 0.98 | 0.98 | 0.97 | 0.91 |
| Ball of foot length | 0.95 | 0.74 | 0.97 | 0.68 |
| Outside ball of foot length | 0.95 | 0.89 | 0.94 | 0.98 |
| Foot breadth diagonal | 0.95 | 0.89 | 0.98 | 0.59 |
| Foot breadth horizontal | 0.96 | 0.84 | 0.98 | 0.93 |
| Heel breadth | 0.96 | 0.87 | 0.94 | 0.78 |
Figure 3Measuring foot breadth horizontal dimension by using (a) scanning image and (b) digital caliper.