A South African podometric study - Does the shoe fit the foot?

Footwear is manufactured from foot forms or moulds known as “lasts”, based on certain measurements of the feet for whom the footwear is intended. Measurement or morphometric studies of the foot in other populations reveal differences due to genetic, ethnic and/or racial differences. Most last measurements used in the South African (SA) footwear industry are based on the British (UK) standard and assume an average fit for the entire population. No three dimensional (3-D) measurement data existed on the SA female foot that was statistically representative of all major ethnic groups of the female population. This was needed to test the current applicability of the UK standard, in light of previous findings that 80% of a random sample of South African women reported foot pathology ascribed to ill-fitting footwear. Further, this would address a suggestion that foot measurements might be non-linear in grading between small size individuals (size 3, 4 and 5) and large size individuals (size 8, 9 and 10). This study essentially consists of three parts. First, a preliminary study undertook to find or create a suitable and affordable method of 3-D input, not only to obtain morphometric measurements but also to capture the topography of the weight bearing foot for future research and development of contoured foot beds for industry. Second, a comparison of specific measurements from a UK size 4 last and the corresponding foot measurements from a sampled population of size 4 foot length was performed, in order to determine what percentage of women would fit the footwear derived from such a last. Third, a comparison of mean values was carried out between data from participants of all sizes scaled down arithmetically to UK size 4 length, and data from actual size 4 participants, in order to explore whether the size 4, occurring as it does near the lower end of the size range, could still be representative of the proportional measurements for sizes 3 to 10. The mean values of this second scaled size 4 group were also compared to the UK size 4 last measurements. The first part of the study utilized the resources of collaborative partners to locate 3-D hardware and software. Experimentation with compounds isolated a suitable impression material and platform designs were conceived to facilitate the data capture method developed. The invented method was awarded patent rights. The second part of the study used the method developed from the preliminary study to conduct measurements. 3-D Laser scanning in combination with manual measurement for validation, by convenience sampling of each of 510 active women aged 21 to 69, of differing ethnic origins, in two major urban regions, yielded 13 foot measurements of each participant. Last measurements were captured by means of comparable laser scanning of a UK size 4 last. In the second part of the study, eight of the comparable measurements for size 4 feet and the last were compared for accuracy of fit. The third part of the study compared mean values between data from non size 4 participants scaled down arithmetically to UK size 4 length, and data from actual size 4 participants. Part one of the study successfully developed and patented a new, portable, low-cost method which can be used to measure either a last or foot in 3-D for any footwear consumer group. Results of the metric study in part two indicate that four dimensions of the industry standard last do not fit the corresponding four dimensions of the average foot measured, namely forefoot girth, forefoot width, heel width and minor foot length (heel to fifth toe). More than 75.6% of participants from every ethnic group displayed tread girths larger than that of the last. These findings have serious implications since deficit fit in any of these four dimensions impacts negatively on foot health and function within the shoe. As such, results could not support the null hypothesis that the shoe fits the foot. Results in the third part of the study yielded similar mean values for measurement parameters between the two groups of data, indicating that the mean measurements for a size 4, even though it is placed near the lower end of the size range, can be representative of the mean scaleable measurements for sizes 3 to 10 but only for the length grade. In conclusion, the study developed and patented a new method for a scientific process to record the weight bearing foot in 3-D. It produced the first national database of 3-D measurements of a female population on the African continent. Outcomes included new prototypes, innovation and technology transfer to industry. The study prompted the development of new footwear by the manufacturing industry partner, utilizing information gained from the study. The study has given impetus to continuing research on the African foot.Mrs. Saramarie Eagleton Doctor Bernhard Zipfe