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A comparison of foot arch measurement reliability using both digital photography and calliper methods.

Pohl MB, Farr L - J Foot Ankle Res (2010)

Bottom Line: AHI values calculated using the digital photographic method tended to be greater than those derived using the AHIMS.While AHI measurements calculated using both methods were highly related, the greater AHI values in the photographic method implied caution should be exercised when comparing absolute values between the two methods.Future studies are required to determine whether digital photographic methods can be developed with improved validity.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Kinesiology, University of Calgary, AB, Canada. mbpohl@ucalgary.ca.

ABSTRACT

Background: Both calliper devices and digital photographic methods have been used to quantify foot arch height parameters. The purpose of this study was to compare the reliability of both a calliper device and digital photographic method in determining the arch height index (AHI).

Methods: Twenty subjects underwent measurements of AHI on two separate days. On each day, AHI measurements during both sitting and standing were taken using the AHIMS and digital photographic methods by the same single tester. The intra-tester reliability of each measurement technique was assessed using intraclass correlation coefficients (ICC) and standard error of measurement (SEM). Additionally, the relationship between AHI measurements derived from the two different methods was assessed using a correlation analysis.

Results: The reliability for both the AHIMS and digital photographic methods was excellent with ICC values exceeding 0.86 and SEM values of less than 0.009 for the AHI. Moreover, the reliability of both measurement techniques was equivalent. There was a strong positive correlation between the AHI values collected using both methods. AHI values calculated using the digital photographic method tended to be greater than those derived using the AHIMS.

Conclusion: Digital photographic methods offer equivalent intra-tester reliability to previously established calliper methods when assessing AHI. While AHI measurements calculated using both methods were highly related, the greater AHI values in the photographic method implied caution should be exercised when comparing absolute values between the two methods. Future studies are required to determine whether digital photographic methods can be developed with improved validity.

No MeSH data available.


Digital photographic image used to calculate FL, TFL and AH. Lines were drawn on the image indicating the distal end of the hallux, the most posterior aspect of the posterior heel, and the horizontal supporting surface. The co-ordinates A-E were digitized and used to calculate the foot measurements. The horizontal distance between A and B gave FL. Point C was placed at the horizontal midpoint between A and B. The vertical distance between C and D represents AH. The horizontal distance between B and E yielded the TFL.
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Figure 3: Digital photographic image used to calculate FL, TFL and AH. Lines were drawn on the image indicating the distal end of the hallux, the most posterior aspect of the posterior heel, and the horizontal supporting surface. The co-ordinates A-E were digitized and used to calculate the foot measurements. The horizontal distance between A and B gave FL. Point C was placed at the horizontal midpoint between A and B. The vertical distance between C and D represents AH. The horizontal distance between B and E yielded the TFL.

Mentions: All digital photos were then downloaded onto a PC where they were processed using ImageJ software (NIH, Bethesda, USA). Briefly, this software allowed the digitizing of selected co-ordinates to calculate the foot measurements needed to determine AHI (Figure 3). Co-ordinates were exported from the software as pixels and the calibration photo allowed the conversion of pixels to cm. To assist with the digitizing of the foot photos lines were drawn on the image indicating the distal end of the hallux, the most posterior aspect of the posterior heel, and the horizontal supporting surface (Figure 3). The FL was obtained by digitizing points at the distal end of the hallux and posterior aspect of the heel. The total foot length was then halved to determine 50% of the total foot length. An additional vertical line was then drawn perpendicular from the supporting surface to the dorsum of the foot at 50% of the foot length. The DH was determined by digitizing co-ordinates at the top and bottom of this line. Finally, a co-ordinate on the first metatarsal head was digitized to enable the calculation of TFL. No enhancements or modifications were made to any of the digital images.


A comparison of foot arch measurement reliability using both digital photography and calliper methods.

Pohl MB, Farr L - J Foot Ankle Res (2010)

Digital photographic image used to calculate FL, TFL and AH. Lines were drawn on the image indicating the distal end of the hallux, the most posterior aspect of the posterior heel, and the horizontal supporting surface. The co-ordinates A-E were digitized and used to calculate the foot measurements. The horizontal distance between A and B gave FL. Point C was placed at the horizontal midpoint between A and B. The vertical distance between C and D represents AH. The horizontal distance between B and E yielded the TFL.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2914096&req=5

Figure 3: Digital photographic image used to calculate FL, TFL and AH. Lines were drawn on the image indicating the distal end of the hallux, the most posterior aspect of the posterior heel, and the horizontal supporting surface. The co-ordinates A-E were digitized and used to calculate the foot measurements. The horizontal distance between A and B gave FL. Point C was placed at the horizontal midpoint between A and B. The vertical distance between C and D represents AH. The horizontal distance between B and E yielded the TFL.
Mentions: All digital photos were then downloaded onto a PC where they were processed using ImageJ software (NIH, Bethesda, USA). Briefly, this software allowed the digitizing of selected co-ordinates to calculate the foot measurements needed to determine AHI (Figure 3). Co-ordinates were exported from the software as pixels and the calibration photo allowed the conversion of pixels to cm. To assist with the digitizing of the foot photos lines were drawn on the image indicating the distal end of the hallux, the most posterior aspect of the posterior heel, and the horizontal supporting surface (Figure 3). The FL was obtained by digitizing points at the distal end of the hallux and posterior aspect of the heel. The total foot length was then halved to determine 50% of the total foot length. An additional vertical line was then drawn perpendicular from the supporting surface to the dorsum of the foot at 50% of the foot length. The DH was determined by digitizing co-ordinates at the top and bottom of this line. Finally, a co-ordinate on the first metatarsal head was digitized to enable the calculation of TFL. No enhancements or modifications were made to any of the digital images.

Bottom Line: AHI values calculated using the digital photographic method tended to be greater than those derived using the AHIMS.While AHI measurements calculated using both methods were highly related, the greater AHI values in the photographic method implied caution should be exercised when comparing absolute values between the two methods.Future studies are required to determine whether digital photographic methods can be developed with improved validity.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Kinesiology, University of Calgary, AB, Canada. mbpohl@ucalgary.ca.

ABSTRACT

Background: Both calliper devices and digital photographic methods have been used to quantify foot arch height parameters. The purpose of this study was to compare the reliability of both a calliper device and digital photographic method in determining the arch height index (AHI).

Methods: Twenty subjects underwent measurements of AHI on two separate days. On each day, AHI measurements during both sitting and standing were taken using the AHIMS and digital photographic methods by the same single tester. The intra-tester reliability of each measurement technique was assessed using intraclass correlation coefficients (ICC) and standard error of measurement (SEM). Additionally, the relationship between AHI measurements derived from the two different methods was assessed using a correlation analysis.

Results: The reliability for both the AHIMS and digital photographic methods was excellent with ICC values exceeding 0.86 and SEM values of less than 0.009 for the AHI. Moreover, the reliability of both measurement techniques was equivalent. There was a strong positive correlation between the AHI values collected using both methods. AHI values calculated using the digital photographic method tended to be greater than those derived using the AHIMS.

Conclusion: Digital photographic methods offer equivalent intra-tester reliability to previously established calliper methods when assessing AHI. While AHI measurements calculated using both methods were highly related, the greater AHI values in the photographic method implied caution should be exercised when comparing absolute values between the two methods. Future studies are required to determine whether digital photographic methods can be developed with improved validity.

No MeSH data available.