Reliability of different negative model techniques

NewsBot · Jul 25, 2012

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Computer-aided design of customized foot orthoses: reproducibility and effect of method used to obtain foot shape.
Telfer S, Gibson KS, Hennessy K, Steultjens MP, Woodburn J.
Arch Phys Med Rehabil. 2012 May;93(5):863-70.

OBJECTIVE:
To determine, for a number of techniques used to obtain foot shape based around plaster casting, foam box impressions, and 3-dimensional scanning, (1) the effect the technique has on the overall reproducibility of custom foot orthoses (FOs) in terms of inter- and intracaster reliability and (2) the reproducibility of FO design by using computer-aided design (CAD) software in terms of inter- and intra-CAD operator reliability for all these techniques.

DESIGN:
Cross-sectional study.

SETTING:
University laboratory.

PARTICIPANTS:
Convenience sample of individuals (N=22) with noncavus foot types.

INTERVENTIONS:
Not applicable.

MAIN OUTCOME MEASURES:
Parameters of the FO design (length, width at forefoot, width at rearfoot, and peak medial arch height), the forefoot to rearfoot angle of the foot shape, and overall volume match between device designs.

RESULTS:
For intra- and intercaster reliability of the different methods of obtaining the foot shape, all methods fell below the reproducibility quality threshold for the medial arch height of the device, and volume matching was <80% for all methods. The more experienced CAD operator was able to achieve excellent reliability (intraclass correlation coefficients >0.75) for all variables with the exception of forefoot to rearfoot angle, with overall volume matches of >87% of the devices.

CONCLUSIONS:
None of the techniques for obtaining foot shape met all the criteria for excellent reproducibility, with the peak arch height being particularly variable. Additional variability is added at the CAD stage of the FO design process, although with adequate operator experience good to excellent reproducibility may be achieved at this stage. Taking only basic linear or angular measurement parameters from the device may fail to fully capture the variability in FO design.
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Admin2 · Jul 26, 2012

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NewsBot · Dec 5, 2018

Comparative Study Between the Different Techniques of Molding and the Morphology of the Foot in Weightbearing.
María José Manfredi Márquez, Priscila Távara Vidalón, Nuria Lara Hurtado, and Javier Ramos-Ortega
Journal of the American Podiatric Medical Association: September 2018, Vol. 108, No. 5, pp. 375-382.

Background: Taking a mold of the foot is an important advance for podiatric medicine and an indispensable procedure for the individualization of orthopedic treatments. We sought to determine which method of measuring molds (plaster cast in weightbearing and nonweightbearing and phenolic foam in weightbearing) reproduces with more reliability the expansion of the foot in weightbearing by comparing the widths of the forefoot and hindfoot in the different methods and in barefoot weightbearing.

Methods: In 54 patients, we studied the differences in width between the forefoot and hindfoot in barefoot weightbearing compared with in the different mold obtainment techniques. A descriptive, observational, and transversal study was performed in which foot molds were obtained with the different techniques, without corrective maneuvers, followed by scanning of each as well as barefoot weightbearing.

Results: Significant differences among the techniques were shown, with phenolic foam being more similar to barefoot weightbearing in forefoot and hindfoot width.

Conclusions: The method that reproduces the expansion of the foot in weightbearing with more reliability is phenolic foam. The forefoot width is superior in barefoot weightbearing versus the three foot casts studied. The hindfoot width is superior in the foot cast with plaster in weightbearing compared with barefoot weightbearing and the other two foot casts.
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NewsBot · Jan 9, 2021

Comparison of 3D scanning versus traditional methods of capturing foot and ankle morphology for the fabrication of orthoses: a systematic review
Muhannad Farhan, Joyce Zhanzi Wang, Paula Bray, Joshua Burns & Tegan L. Cheng
Journal of Foot and Ankle Research volume 14, Article number: 2 (2021)

Background
In the production of ankle-foot orthoses and in-shoe foot orthoses, lower leg morphology is traditionally captured using a plaster cast or foam impression box. Plaster-based processes are a time-consuming and labour-intensive fabrication method. 3D scanning is a promising alternative, however how these new technologies compare with traditional methods is unclear. The aim of this systematic review was to compare the speed, accuracy and reliability of 3D scanning with traditional methods of capturing foot and ankle morphology for fabricating orthoses.

Methods
PRISMA guidelines were followed and electronic databases were searched to March 2020 using keywords related to 3D scanning technologies and traditional foot and ankle morphology capture methods. Studies of any design from healthy or clinical populations of any age and gender were eligible for inclusion. Studies must have compared 3D scanning to another form of capturing morphology of the foot and/or ankle. Data relating to speed, accuracy and reliability as well as study design, 3D scanner specifications and comparative capture techniques were extracted by two authors (M.F. and Z.W.). Study quality was assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) and Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN).

Results
Six articles met the inclusion criteria, whereby 3D scanning was compared to five traditional methods (plaster cast, foam impression box, ink footprint, digital footprint and clinical assessment). The quality of study outcomes was rated low to moderate (GRADE) and doubtful to adequate (COSMIN). Compared to traditional methods, 3D scanning appeared to be faster than casting (2 to 11 min vs 11 to 16 min). Inter-rater reliability (ICC 0.18–0.99) and intra-rater reliability (ICCs 0.25–0.99) were highly variable for both 3D scanning and traditional techniques, with higher agreement generally dependent on the foot parameter measured.

Conclusions
The quality and quantity of literature comparing the speed, accuracy and reliability of 3D scanning with traditional methods of capturing foot and ankle morphology is low. 3D scanning appears to be faster especially for experienced users, however accuracy and reliability between methods is variable.
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NewsBot · Apr 9, 2021

3D optical scanning as an objective and reliable tool for volumetry of the foot and ankle region
BenHofmannaKatjaKonopkaaDagmar-ChristianeFischerbGüntherKundtcHeinerMartindThomasMittlmeiera
Foot and Ankle Surgery; 16 March 2021

Highlights
•Formation of foot and ankle edema is a well-known clinical problem.
•Ankle volume and the perimeter of the figure-of-eight are highly correlated.
•3D optical scanning allows contactless assessment of the foot and ankle volume.
•3D optical scanning turned out to be highly reliable.
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Background
Edema development of the foot and ankle region should be evaluated by an objective measurement. We hypothesized, that 3D optical scanning of this region can serve as an alternative to clinically established measurement techniques.

Methods
Two investigators determined the volume by 3D optical scanning and the figure-of-eight method in a random order at 2 separate time points. Plots were created and ICCs were calculated for determination of reliability. The Pearson correlation coefficient served as a measure of the association between both measures.

Results
40 healthy volunteers with mean age of 28.3 ± 9.9 years underwent four sequences of measurements. The inter- and intraobserver reliability of both methods was excellent with high intraclass correlation coefficients (ICC 3,1). A strong correlation (r = 0.96, P < 0.001) between measured ankle volumes was noted.

Conclusion
3D optical scanning turned out to be more reliable than the figure-of-eight method in a preclinical set-up. A clinical use should be aimed at.
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NewsBot · Nov 1, 2021

Evaluation of Usability of the Tiger Full Foot 3D Scanner for the Measurements of Basic Foot Dimensions in Clinical Practice
Ondřej Laštovička, Roman Cuberek, Miroslav Janura, Tomáš Klein
J Am Podiatr Med Assoc. 2021 Oct 26;20-019

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.
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NewsBot The Admin that posts the news.

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