• 1

    Helmick, CG, DT Felson, RC Lawrence, et al. :Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. .Arthritis Rheum 58::15. ,2008. .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Grondal, L, B Tengstrand, B Nordmark, et al. :The foot: still the most important reason for walking incapacity in rheumatoid arthritis: distribution of symptomatic joints in 1,000 RA patients. .Acta Orthopaed 79::257. ,2008. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3

    Michelson, J, M Easley, FM Wigley, et al. :Foot and ankle problems in rheumatoid-arthritis. .Foot Ankle Int 15::608. ,1994. .

  • 4

    Billis, E, E Katsatkiori, C Kapodistrias, et al. :Assessment of foot posture: correlation between different clinical techiniques. .The Foot 17::65. ,2007. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5

    Platto, MJ, PG Oconnell, JE Hicks, et al. :The relationship of pain and deformity of the rheumatoid foot to gait and an index of functional ambulation. .J Rheumatol 18::38. ,1991. .

    • Search Google Scholar
    • Export Citation
  • 6

    Redmond, AC, J Crosbie, and RA Ouvrier. :Development and validation of a novel rating system for scoring standing foot posture: the Foot Posture Index. .Clin Biomech 21::89. ,2006. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7

    Budiman-Mak, E, KE Roach, R Stuck, et al. :Radiographic measurement of hallux valgus in the rheumatoid arthritic foot. .J Rheumatol 21::623. ,1994. .

  • 8

    Mall, NA, WM Hardaker, JA Nunley, et al. :The reliability and reproducibility of foot type measurements using a mirrored foot photo box and digital photography compared to caliper measurements. .J Biomech 40::1171. ,2007. .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Chen, MJ, CP Chen, HL Lew, et al. :Measurement of forefoot varus angle by laser technology in people with flexible flatfoot. .Am J Phys Med Rehabil 82::842. ,2003. .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    Liu, X, W Kim, and B Drerup. :“3D Characterization and Localization of Anatomical Landmarks of the Foot,”. inProceedings of the 2004 ACM SIGGRAPH International Conference on Virtual Reality Continuum and Its Applications in Industry. , p253. ,Association for Computing Machinery. ,New York. ,2004. .

    • Search Google Scholar
    • Export Citation
  • 11

    Mochimaru, M, M Kouchi, and M Dohi. :Analysis of 3-D human foot forms using the Free Form Deformation method and its application in grading shoe lasts. .Ergonomics 43::1301. ,2000. .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Tsung, BY, M Zhang, YB Fan, et al. :Quantitative comparison of plantar foot shapes under different weight-bearing conditions. .J Rehabil Res Dev 40::517. ,2003. .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Witana, CP, SP Xiong, JH Zhao, et al. :Foot measurements from three-dimensional scans: a comparison and evaluation of different methods. .Int J Industrial Ergonom 36::789. ,2006. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14

    Houston, VL, G Luo, CP Mason, et al. :Changes in male foot shape and size with weightbearing. .JAPMA 96::330. ,2006. .

  • 15

    Liu, W, J Miller, D Stefanyshyn, et al. :Accuracy and reliability of a technique for quantifying foot shape, dimensions and structural characteristics. .Ergonomics 42::346. ,1999. .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16

    Luximon, A, RS Goonetilleke, and M Zhang. :3D foot shape generation from 2D information. .Ergonomics 48::625. ,2005. .

  • 17

    Krauss, I, S Grau, M Mauch, et al. :“Female Foot Morphology: Implications for Last Design,”. Proceedings of the 8th Footwear Biomechanics Symposium, Taipei 2007. , ed byFrederick, EC and SW Yang. p39. ,Footwear Biomechanics Corp. ,Brentwood, OH. ,2007. .

    • Search Google Scholar
    • Export Citation
  • 18

    Kunde, S, T Sterzing, and T Milani. :“The Influence of Body Position and Physical Activity on Foot Dimensions Measured by a Foot Scanning System,”. Proceedings 8th Footwear Biomechanics Symposium, Taipei 2007. , ed byFrederick, EC and SW Yang. p43. ,Footwear Biomechanics Corp. ,Brentwood, OH. ,2007. .

    • Search Google Scholar
    • Export Citation
  • 19

    Witana, CP, J Feng, and RS Goonetilleke. :Dimensional differences for evaluating the quality of footwear fit. .Ergonomics 47::1301. ,2004. .

  • 20

    Arnett, FC, SM Edworthy, DA Bloch, et al. :The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis. .Arthritis Rheum 31::315. ,1988. .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Coorevits, P, L Danneels, D Cambier, et al. :Test-retest reliability of wavelet- and Fourier based EMG (instantaneous) median frequencies in the evaluation of back and hip muscle fatigue during isometric back extensions. .J Electromyogr Kinesiol 18::798. ,2008. .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Weir, JP . :Quantifying test-retest reliability using the intraclass correlation coefficient and the SEM. .J Strength Cond Res 19::231. ,2005. .

  • 23

    Atkinson, G and AM Nevill. :Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine. .Sports Med 26::217. ,1998. .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Portney, L and M Watkins. :“Statistical Measures of Reliability,”. inFoundations of Clinical Research: Applications to Practice. , ed byCohen, M. p585. ,Pearson Education International. ,Upper Saddle River, NJ. ,2009. .

    • Search Google Scholar
    • Export Citation
  • 25

    Angst, F, A Aeschlimann, and G Stucki. :Smallest detectable and minimal clinically important differences of rehabilitation intervention with their implications for required sample sizes using WOMAC and SF-36 quality of life measurement instruments in patients with osteoarthritis of the lower extremities. .Arthritis Rheum 45::384. ,2001. .

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 26

    Lassere, MN, D van der Heijde, KR Johnson, et al. :Reliability of measures of disease activity and disease damage in rheumatoid arthritis: implications for smallest detectable difference, minimal clinically important difference, and analysis of treatment effects in randomized controlled trials. .J Rheumatol 28::892. ,2001. .

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 27

    Anastasi, A . :Psychological Testing, ,6th Ed. ,Macmillan Publishing Co. ,New York. ,1988. .

  • 28

    Ibrahim, T, A Beiri, M Azzabi, et al. :Reliability and validity of the subjective component of the American Orthopaedic Foot and Ankle Society clinical rating scales. .J Foot Ankle Surg 46::65. ,2007. .

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 29

    Shrout, PE and JL Fleiss. :Intraclass correlations: uses in assessing rater reliability. .Psychol Bull 86::420. ,1979. .

  • 30

    Wrobel, JS and DG Armstrong. :Reliability and validity of current physical examination techniques of the foot and ankle. .JAPMA 98::197. ,2008. .

    • Search Google Scholar
    • Export Citation

Reliability and Validity of the INFOOT Three-dimensional Foot Digitizer for Patients with Rheumatoid Arthritis

Sophie De Mits Department of Rehabilitation Sciences and Physiotherapy, Ghent University & Artevelde University

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Pascal Coorevits Department of Public Health and RAMIT vzw, Ghent University, Ghent, Belgium

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Dirk De Clercq Department of Movement and Sport Sciences, Ghent University, Ghent, Belgium

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Dirk Elewaut Department of Rheumatology, Ghent University Hospital, Ghent, Belgium

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James Woodburn School of Health and Social Care and HealthQWest, Glasgow Caledonian University, Glasgow, Scotland

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Philip Roosen Department of Rehabilitation Sciences and Physiotherapy, Ghent University & Artevelde University

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Background:

Abnormal foot posture and deformities are identified as important features in rheumatoid arthritis. There is still no consensus regarding the optimum technique(s) for quantifying these features; hence, a foot digitizer might be used as an objective measurement tool. We sought to assess the validity and reliability of the INFOOT digitizer.

Methods:

To investigate the validity of the INFOOT digitizer compared with clinical measurements, we calculated Pearson correlation coefficients. To investigate the reliability of the INFOOT digitizer, we calculated intraclass correlation coefficients, SEMs, smallest detectable differences, and smallest detectable difference percentages.

Results:

Most of the 38 parameters showed good intraclass correlation coefficients, with values greater than 0.9 for 30 parameters and greater than 0.8 for seven parameters. The left heel bone angle expressed a moderate correlation, with a value of 0.609. The SEM values varied between 0.31 and 3.51 mm for the length and width measures, between 0.74 and 5.58 mm for the height data, between 0.75 and 5.9 mm for the circumferences, and between 0.78° and 2.98° for the angles. The smallest detectable difference values ranged from 0.86 to 16.36 mm for length, width, height, and circumference measures and from 2.17° to 8.26° for the angle measures. For the validity of the INFOOT three-dimensional foot digitizer, Pearson correlation coefficients varied between 0.750 and 0.997.

Conclusions:

In this rheumatoid arthritis population, good validity was demonstrated compared with clinical measurements, and most of the obtained parameters proved to be reliable. (J Am Podiatr Med Assoc 101(3): 198–207, 2011)

Corresponding author: Sophie De Mits, PT, BPod, Department of Rehabilitation Sciences and Physiotherapy, Ghent University & Artevelde University College, De Pintelaan 185 Gent, 9000, Belgium. (E-mail: Sophie.DeMits@UGent.be)