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The Relationship Between Arch Height and Arch Flexibility
A Proposed Arch Flexibility Classification System for the Description of Multidimensional Foot Structure
Background:
The correlation between arch structure and injury may be related to the fact that foot structure influences foot function. Foot structure is often defined by arch height, although arch flexibility may be just as important to form a more complete description. We propose an arch flexibility classification system, analogous to arch height classification, and then use the classification system to examine the relationship between arch flexibility and arch height.
Methods:
Arch height index was calculated in 1,124 incoming military cadets, of whom 1,056 had usable data. By measuring arch height during both sitting and standing, a measurement of arch flexibility could also be calculated. These values were used to create five arch flexibility categories: very stiff, stiff, neutral, flexible, and very flexible. The distribution of arch flexibility types among arch height categories was statistically compared.
Results:
The goodness of fit test showed a disproportionate number of each arch flexibility type in each of the arch height categories (P < .01). The largest proportion of cavus feet was very stiff and the smallest proportion was very flexible. Conversely, the largest proportion of planus feet was very flexible and the smallest proportion was very stiff.
Conclusions:
The results of this research support the common belief that cavus feet tend to be very stiff and planus feet tend to be very flexible.
Background
Low-Dye taping is commonly used to manage foot pathologies and pain. Precut one-piece QUICK TAPE was designed to facilitate taping. However, no study to date has demonstrated that QUICK TAPE offers similar support and off-loading as traditional taping.
Methods
This pilot study compared the performance of QUICK TAPE and low-Dye taping in 20 healthy participants (40 feet) with moderate-to-severe pes planus. Study participants completed arch height index (AHI), dynamic plantar assessment with a plantar pressure measurement system, and subjective rating in three conditions: barefoot, low-Dye, and QUICK TAPE. The order of test conditions was randomized for each participant, and the taping was applied to both feet based on a standard method. A generalized estimating equation with an identity link function was used to examine differences across test conditions while accounting for potential dependence in bilateral data.
Results
Participants stood with a significantly greater AHI (P = .007) when either taping was applied compared with barefoot. Participants also demonstrated significantly different plantar loading when walking with both tapings versus barefoot. Both tapings yielded reduced force-time integral (FTI) in the medial and lateral forefoot and increased FTI under toes. Unlike previous studies, however, no lateralization of plantar pressure was observed with either taping. Participants ranked both tapings more supportive than barefoot. Most participants (77.8%) ranked low-Dye least comfortable, and 55.6% preferred QUICK TAPE over low-Dye.
Conclusions
Additional studies are needed to examine the clinical utility of QUICK TAPE in individuals with foot pathologies such as heel pain syndrome and metatarsalgia.
Background:
Anthropometric status can influence gait biomechanics, but there is relatively little published research regarding foot and ankle characteristics in the obese pediatric population. We sought to compare the structural and functional characteristics of the foot and ankle complex in obese and non-obese children.
Methods:
Twenty healthy children (ten obese and ten normal weight) were recruited for a cross-sectional research study. Anthropometric parameters were measured to evaluate active ankle dorsiflexion, arch height (arch height index, arch rigidity index ratio, and arch drop), foot alignment (resting calcaneal stance position and forefoot-rearfoot alignment in unloaded and loaded positions), and foot type (malleolar valgus index). Independent t tests determined significant differences between groups for all assessed parameters. Statistical significance was set at P < .0125.
Results:
Compared with non-obese participants, obese participants had significantly greater arch drop (mean ± SD: 5.10 ± 2.13 mm versus 2.90 ± 1.20 mm; P =.011) and a trend toward lower arch rigidity index ratios (mean ± SD: 0.92 ± 0.03 versus 0.95 ± 0.02; P = .013). In addition, obese participants had significantly less active ankle dorsiflexion at 90° of knee flexion versus non-obese participants (mean ± SD: 19.57 ± 5.17 versus 29.07 ± 3.06; P < .001). No significant differences existed between groups for any other anthropometric measurements.
Conclusions:
The decreased active ankle dorsiflexion in the obese group can increase foot contact for a longer period of the stance phase of gait. Obese participants also presented with a more flexible foot when bearing weight. (J Am Podiatr Med Assoc 102(1): 5–12, 2012)
Arch Height Index Measurement System
Establishment of Reliability and Normative Values
Background: The purposes of this study were 1) to determine the intrarater and interrater reliability of the arch height index measurement system device, 2) to establish population normative values for the arch height index in recreational runners, and 3) to compare arch height index values between the right and left feet and between genders.
Methods: Eleven subjects were used to establish intrarater and interrater reliability of the arch height index measurement system. This system was then used to measure the arch height index of 100 recreational runners.
Results: Measurements taken with the arch height index measurement system device exhibited high intrarater and interrater reliability. The mean ± SD arch height index of the recreational runners was 0.340 ± 0.030. Men had larger feet than women, but the arch height index between genders was similar.
Conclusions: The arch height index measurement system device is reliable to use between testers while simplifying the measurement procedure for recording the arch height index. The arch height index may be helpful in identifying potential structural factors that predispose individuals to lower-extremity injuries. (J Am Podiatr Med Assoc 98(2): 102–106, 2008)
Stability of the Offset V-Osteotomy
Test Jig Development and Saw Bone Model Assessment
In the offset V-bunionectomy used for hallux valgus repair, both the Kalish and the Vogler variations have a long dorsal arm, but the apex is more distal in the Kalish procedure. This study investigated the effect that pin orientation and location of the osteotomy apex have on weightbearing stability. The authors studied saw bone models that were loaded to failure in an Instron 4201 materials testing machine and, in addition, designed, fabricated, and used a unique jig assembly to help minimize data variability. Statistically significant differences were found between the surgical techniques and pin orientations: the Kalish osteotomy was stronger than the Vogler procedure, and in both osteotomies, the plantarly directed Kirschner wire orientation was stronger than the dorsally directed orientation. (J Am Podiatr Med Assoc 92(2): 82-89, 2002)
INTRODUCTION AND OBJECTIVES: Healthy feet are important for overall health and well-being. Previous studies of older subjects showed that those with a lowered arch had an increased odds of having foot deformities, pain, and hyperpronation in gait. (1–3) No investigation to date has comprehensively characterized foot biomechanics in a large sample of healthy active young subjects.
METHODS: Foot structure, function, and arch height flexibility (AHF) were measured in 1,052 incoming cadets to the United States Military Academy. Based on the previously established standing arch height index (AHI), 70% of subjects exhibited planus foot structures. (4,5) To examine the effects of AHF on dynamic barefoot plantar pressure, 1,414 planus feet were further categorized by AHF. Those that fell within the highest and the lowest quintiles were defined as flexible and stiff AHF, respectively, while the middle 3 quintiles were categorized as referent.
RESULTS: Descriptive statistics and normality testing were performed using SPSS software version 22 (IBM, Chicago, IL, USA). A Generalized Linear Model with an identify link function was used to examine the effects of AHF category while accounting for potential dependence in bilateral data. The Wald Chi-square was calculated for each dependent variable with significance set at p < 0.05. Post hoc pairwise comparisons for all pairs were performed using the Generalized Chi Square test at P < 0.017.
CONCLUSIONS: A significant difference was found in Center of Pressure Excursion Index (CPEI) and Peak Pressure (PP). Post hoc pairwise comparisons showed a significant difference between flexible versus stiff AHF: those with flexible AHF exhibited reduced CPEI (greater hyperpronation) while those with stiff AHF showed elevated PP. Results suggest that, in addition to AHI, the arch flexibility may affect dynamic foot function. This was a part of larger study. Additional studies are needed to examine the effects of AHI and AHF on regional plantar loading and overuse injuries.
Background:
In a previous pilot study of “cruisers” (nonindependent ambulation), “early walkers” (independent ambulation for 0–5 months), and “experienced walkers” (independent ambulation for 6–12 months), developmental age significantly affected the children’s stability when walking and performing functional activities. We sought to examine how shoe structural characteristics affect plantar pressure distribution in early walkers.
Methods:
Torsional flexibility was evaluated in four shoe designs (UltraFlex, MedFlex, LowFlex, and Stiff based on decreasing relative flexibility) with a structural testing machine. Plantar pressures were recorded in 25 early walkers while barefoot and shod at self-selected walking speeds. Peak pressure was calculated over ten masked regions for the barefoot and shod conditions.
Results:
Torsional flexibility, the angular rotation divided by the applied moment about the long axis of the shoe, was different across the four shoe designs. As expected, UltraFlex was the most flexible and Stiff was the least flexible. As applied moment increased, torsional flexibility decreased in all footwear. When evaluating early walkers during gait, peak pressure was significantly different across shoe conditions for all of the masked regions. The stiffest shoe had the lowest peak pressures and the most flexible shoe had the highest.
Conclusions:
It is likely that increased shoe flexibility promoted greater plantar loading. Plantar pressures while wearing the most flexible shoe are similar to those while barefoot. This mechanical feedback may enhance proprioception, which is a desirable attribute for children learning to walk. (J Am Podiatr Med Assoc 103(4): 297–305, 2013)
