Search Results
Background:
Accurate representation of the insole geometry is crucial for the development and performance evaluation of foot orthoses designed to redistribute plantar pressure, especially for diabetic patients.
Methods:
Considering the limitations in the type of equipment and space available in clinical practices, this study adopted a simple portable three-dimensional (3-D) desktop scanner to evaluate the 3-D geometry of an orthotic insole and the corresponding deformities after the insole has been worn. The shape of the insole structure along horizontal cross sections is defined with 3-D scanning and image processing. Accompanied by an in-shoe pressure measurement system, plantar pressure distribution in four foot regions (hallux, metatarsal heads, midfoot, and heel) is analyzed and evaluated for insole deformity.
Results:
Insole deformities are quantified across the four foot regions. The hallux region tends to show the greatest changes in shape geometry (17%–50%) compared with the other foot regions after 2 months of insole wear. As a result of insole deformities, plantar peak pressures change considerably (–4.3% to +69.5%) during the course of treatment.
Conclusions:
Changes in shape geometry of the insoles could be objectively quantified with 3-D scanning techniques and image processing. This investigation finds that, in general, the design of orthotic insoles may not be adequate for diabetic individuals with similar foot problems. The drastic changes in the insole shape geometry and cross-sectional areas during orthotic treatment may reduce insole fit and conformity. An inadequate insole design may also affect plantar pressure reduction. The approach proposed herein, therefore, allows for objective quantification of insole shape geometry, which results in effective and optimal orthotic treatment.
Background: Foot dimension information is important both for footwear design and clinical applications. In recent years, non-contact three-dimensional foot digitizers/scanners became popular as they are non-invasive and are both valid and reliable for the most of measures. Some of them also offer automated calculations of basic foot dimensions. The study aimed to determine test-retest reliability, objectivity, and concurrent validity of the Tiger full foot 3D scanner as well as the relationship between the manual measures of the medial longitudinal arch of the foot and its alternative parameters obtained automatically by the scanner. Methods: Intraclass correlation coefficients and the values of minimal detectable change were used to assess the reliability and objectivity of the scanner. Concurrent validity and the relationship between the arch height measures were determined by the Pearson's correlation coefficient and the limits of agreement between the scanner and the calliper method. Results: Both the relative and absolute agreement between the repeated measurements obtained by the scanner show excellent reliability and objectivity of linear measures and only good to nearly good test-retest reliability and objectivity of the arch height. Correlations between the values obtained by the scanner and the calliper were generally higher in linear measures (rp{greater than or equal to}0.929). The representativeness of state of bony architecture by the soft tissue margin of the medial foot arch demonstrate the lowest correlations among the all measurements (rp{less than or equal to}0.526). Conclusions: The Tiger full foot 3D scanner offers both excellent reliability and objectivity in linear measures, which correspond to those obtained by the calliper method. However, values obtained by the both methods shouldn't be used interchangeably. The arch height measure is less accurate, which could limit its use in some clinical applications. Orthotists and related professions probably appreciate scanner more than other specialists.
Are Three-Dimensional–Printed Foot Orthoses Able to Cover the Podiatric Physician's Needs?
Relationship Between Shore A Hardness and Infilling Density
Background
Current management of foot pain requires foot orthoses (FOs) with various design features (eg, wedging, height) and specific mechanical properties (eg, hardness, volume). Development of additive manufacturing (three-dimensional [3-D] printing) raises the question of applying its technology to FO manufacturing. Recent studies have demonstrated the physical benefits of FO parts with specific mechanical properties, but none have investigated the relationship between honeycomb architecture (HcA) infilling density and Shore A hardness of thermoplastic polyurethane (TPU) used to make FOs, which is the aim of this study.
Methods
Sixteen different FO samples were made with a 3-D printer using TPU (97 Shore A), with HcA infilling density ranging from 10 to 40. The mean of two Shore A hardness measurements was used in regression analysis.
Results
Interdurometer reproducibility was excellent (intraclass correlation coefficient, 0.91; 95% confidence interval [CI], 0.64–0.98; P < .001) and interprinter reproducibility was excellent/good (intraclass correlation coefficient, 0.84; 95% CI, 0.43–0.96; P < .001). Linear regression showed a positive significant relationship between Shore A hardness and HcA infilling density (R2 = 0.955; P < .001). Concordance between evaluator and durometer was 86.7%.
Conclusions
This study revealed a strong relationship between Shore A hardness and HcA infilling density of TPU parts produced by 3-D printing and highlighted excellent concordance. These results are clinically relevant because 3-D printing can cover Shore A hardness values ranging from 40 to 70, representing most FO production needs. These results could provide important data for 3-D manufacturing of FOs to match the population needs.
Background
Maintaining balance is a complex phenomenon that is influenced by a range of sensorimotor factors. Foot posture and mobility may also influence balance and postural sway. Recently, three-dimensional foot scanners have been used to assess foot posture. This tool allows many individuals to be scanned quickly and easily and helps eliminate patients' radiation exposure. The objective of this study was to determine whether static foot posture and mobility are independently associated with postural sway in a large community sample of older women using objective measures of balance status and the recently launched technology of three-dimensional foot scanning.
Methods
This cross-sectional study included 140 community-dwelling elderly women (mean ± SD age, 73.9 ± 5.1 years) recruited in Kasama City, Japan. The postural sway variables were total path length and area and were measured by force plate. We measured static foot posture, sitting and standing navicular height, and mobility using a three-dimensional foot scanner. Foot mobility was determined as the amount of vertical navicular excursion between the positions of the subtalar joint, from neutral in sitting position to relaxed bilateral standing.
Results
After adjusting for potential cofounders, analysis of covariance revealed that sitting navicular height was associated with total path length (P = .038) and area (P = .031). Foot mobility was associated with total path length (P = .018).
Conclusions
These findings suggest that sitting navicular height and foot mobility are associated with postural sway in elderly women and might be an important factor in defining balance control in older adults.
Foot Arch Characterization
A Review, a New Metric, and a Comparison
Background: The medial longitudinal arch of the foot is important because it helps protect the foot from injury. Researchers have developed many measures to quantify the characteristics of the arch, and there is ongoing debate about the suitability of these different metrics. This article compares the various measures related to the foot arch, including a new metric, the midfoot dorsal angle, and then investigates the differences in the dimensional measures among various foot types.
Methods: The right feet of 48 healthy individuals (24 men and 24 women) were measured, and various metrics, including the arch height index, the navicular height to arch length ratio, the arch index, the footprint index, the subjective ranking, the modified arch index, the malleolar valgus index, and the midfoot dorsal angle, were determined.
Results: Correlation analyses showed that the arch index obtained from the inked footprint has a moderate to high correlation (Pearson correlation coefficients >0.50) with all measured foot-type metrics except for the malleolar valgus index. There were no differences in participant age, stature, weight, body mass index, foot length, foot width, and midfoot height among high, normal, and low foot arches. However, the high-arched group had significantly shorter arch lengths but larger navicular heights and higher midfoot dorsal angles compared with the low-arched group. There were differences in force distributions and peak pressures as well. The rearfoot had more loading and greater peak pressure whereas the midfoot had less load in the high-arched group compared with the low-arched group.
Conclusions: The midfoot dorsal angle may be an appropriate metric for characterizing the foot arch because it is quick and easy to measure, without the tedious procedures associated with area calculations and dimension measurements. (J Am Podiatr Med Assoc 100(1): 14–24, 2010)
