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Original Research
J.C. Zuil-Escobar, PT, PhD, Depart-
ment of Physiotherapy, Faculty of
Medicine, CEU-San Pablo University,
Avenida Montepríncipe s/n Boadilla del
Monte, 28668 Madrid, Spain. Address
all correspondence to Mr Zuil-Escobar
at: jczuil@ceu.es.
C.B. Martínez-Cepa, PT, PhD, De-
partment of Physiotherapy, Faculty of
Medicine, CEU-San Pablo University.
J.A. Martín-Urrialde, PT, PhD, Depart-
ment of Physiotherapy, Faculty of
Medicine, CEU-San Pablo University.
A. Gómez-Conesa, PT, PhD, Depart-
ment of Physiotherapy, Faculty of
Medicine, Espinardo Campus, Univer-
sity of Murcia, Murcia, Spain.
[Zuil-Escobar JC, Martínez-Cepa CB,
Martín-Urrialde JA, Gómez-Conesa A.
Evaluating the medial longitudinal arch
of the foot: correlations, reliability, and
accuracy in people with a low arch.
Phys Ther. 2019;99:364–372.]
C
2018 American Physical Therapy As-
sociation
Published Ahead of Print:
December 7, 2018
Accepted: July 16, 2018
Submitted: November 13, 2017
Evaluating the Medial Longitudinal
Arch of the Foot: Correlations,
Reliability, and Accuracy in People
With a Low Arch
Juan C. Zuil-Escobar, Carmen B. Martínez-Cepa, Jose A. Martín-Urrialde,
Antonia Gómez-Conesa
Background. The medial longitudinal arch of the foot is a variable structure, and a
decrease in its height could affect several functions and increase the risk of injuries in the
lower limbs. There are many different techniques for evaluating it.
Objective. The objective of this study was to evaluate the correlations of the Navicular
Drop Test, several footprint parameters, and the Foot Posture Index-6 in people with a low
medial longitudinal arch. Intrarater reliability and interrater reliability were also estimated.
Design. This was a repeated-measures, observational descriptive study.
Methods. Seventy-one participants (53.5% women; mean age =24.13 years; SD =3.41)
were included. All of the parameters were collected from the dominant foot. The corre-
lation coefcients were calculated. The reliability was also calculated using the intraclass
correlation coefcient, 95% CI, and kappa coefcient.
Results. Statistically signicant correlations were obtained between the Navicular Drop
Test and the footprint parameters, with rabsolute values ranging from 0.722 to 0.788.
The Navicular Drop Test and the Foot Posture Index-6 showed an excellent correlation
(Spearman correlation coefcient =0.8), and good correlations (Spearman correlation
coefcient =|0.663–0.703|) were obtained between the footprint parameters and the Foot
Posture Index-6. Excellent intrarater reliability and interrater reliability were obtained for
all of the parameters.
Limitations. Radiographic parameters, the gold standard for evaluating the medial lon-
gitudinal arch height, were not used. In addition, the results of this research cannot be
generalized to people with normal and high medial longitudinal arches.
Conclusions. In participants with a low medial longitudinal arch, the Navicular Drop
Test showed signicant correlations with footprint parameters; correlations were good for
the arch angle and Chippaux-Smirnak Index, and excellent for the Staheli Index. The Foot
Posture Index-6 showed an excellent correlation with the Navicular Drop Test and a good
correlation with the footprint parameters evaluated.All of the parameters showed high
reliability.
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Evaluating the Medial Arch in People With Low Arch
The medial longitudinal arch (MLA) is a
variable structure1and its height could affect several
functions during static standing and walking.2,3A
decrease in the MLA height is related to modications in
the lower limb alignment, including subtalar pronation,4
tibial internal torsion,5tibial internal rotation,6greater
genu recurvatum,5anterior knee laxity,7pelvic
anteversion,8and lumbar lordosis.9The height of the MLA
may affect muscular activity. A Navicular Drop Test (NDT)
score of ≥13 mm is associated with decreased concentric
plantar exion strength compared to normal MLA.10 In
addition, the height of the MLA is considered a relevant
factor for several lower limb pathologies, including medial
tibial stress syndrome,11,12 patellofemoral syndrome,13,14
and noncontact anterior cruciate ligament injuries15 and
foot pain.1
Owing to the consequences of a low MLA, it is necessary
to evaluate the height of the MLA in clinical practice to
obtain information for treatment decisions. The evaluation
of the MLA height comprises several methods.16 Many
parameters can be calculated from the footprints,
including the arch angle (AA), the Staheli Index (SI),17 and
the Chippaux-Smirnak Index (CSI).18 Ink footprint is a
noninvasive method that can be used in clinical practice
and investigation16,19 ,20 but has some limitations, such as
the inaccuracy of measurements and difculties in
interpretation.19 Digital systems overcome these
limitations and are widely used in both clinical practice
and investigation,20 but they are expensive. Clinical
techniques include the navicular measurements.16,20
The NDT was described by Brody21 and shows the
difference (in mm) of the height of the navicular
tuberosity in 2 positions: subtalar neutral position and
relaxedposture.TheNDTisaninexpensive,easy,and
quick method; high NDT values are associated with a low
MLA and pronated foot.21 Posture-related indices are other
methods for evaluating the MLA height.20 The Foot
Posture Index (FPI) is a valid and reliable method used to
quantify foot posture22 and the height of the MLA.20
Although the original FPI evaluated 8 items (FPI-8),23 a
6-item version (FPI-6) was redened and assessed across
the 3 planes of the foot.22,24 Each criterion of the FPI-6 is
scored on a 5-point scale (ranging from −2to+2), and
the scores are summed to provide a total score (ranging
from −12 to +12) for the determination of foot posture.22
The FPI-6 is commonly used in both research and clinical
practice.16,20 ,24,25 Therefore, there are several methods for
studying the height of the MLA. However, clinicians need a
reliable, valid, and inexpensive measurement that is useful
for clinical practice.
To our knowledge, the correlations of the NDT, the
footprint parameters, and the FPI-6 in people with a low
MLA have not yet been studied. The 2 aims of this study
were to evaluate the correlations of the NDT, the footprint
parameters (including the AA, SI, and CSI), and the FPI-6
in people with a low MLA, and to estimate the intrarater
reliability and interrater reliability of these parameters.
Methods
Design
A repeated-measures, observational, descriptive study was
carried out.
Participants
The study included university student volunteers. The
participants were asked to complete a consent form and
were informed about the procedure and the aims of the
study. The principles outlined in the Declaration of
Helsinki of 1975 were observed and the project was
approved by the Research Ethics Committee of Centro de
Estudios Universitarios San Pablo University.
Volunteers were included if their MLA was low. A low MLA
was considered if the NDT presented a value of ≥10
mm.3,26,27 The dominant foot was evaluated in each
volunteer by using the kicking ball test to determine the
dominant limb.28 The following exclusion criteria were
established: had a body mass index (BMI) of ≥30, had
undergone lower extremity surgery, had lower extremity
injuries in the previous 6 months, and had lower limb
deformities. A clinical examination of each volunteer was
performed to determine the presence of leg length
discrepancy, hip anteversion/retroversion, genu
recurvatum/exum, genu varum/valgum, tibial torsion,
tibial varum, or hallux valgus. Volunteers were excluded
when 1 or more deformities were observed. Demographic
variables, including age, sex, height, weight, and BMI,
were collected.
The required sample size was calculated using the
correlations between the NDT and the AA, SI, CSI, and
FPI-6 for the rst 20 participants (age =25.32 years;
SD =4.96). The G-power program was used to calculate
the sample size, using an alpha level of 0.05 and 80%
statistical power. The minimum value in the internal pilot
study and the correlation obtained by Nakhaee et al26
between the NDT and the AI (0.44) were used. The sample
size required was 71 participants.
The intrarater reliability and interrater reliability of the
measurements were also evaluated in the rst 20
participants, with an interval of 48 hours, by 2 physical
therapists with more than 6 years of experience in the use
of these techniques. The testers and participants were
unaware of the reliability results.
Procedure
A modication of the Brody procedure21 was used to
collect the NDT: the participants stood barefoot, in
bilateral standing, on the oor, and the navicular
tuberosity was marked. The lateral and medial aspects of
the talar dome of the foot were palpated. The foot was
everted and inverted until the talus was in a central
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Evaluating the Medial Arch in People With Low Arch
position. This was determined to be the subtalar neutral
position. The distance between the navicular tuberosity
and the oor was measured. The height of the navicular
tuberosity was measured in the relaxed position; the NDT
being the difference between the 2 measurements. The
NDT requires previous training, proving less reliable with
inexperienced raters.29
The footprints were collected using a pressure platform
(Footchecker; Loran Engineering, Bologna, Italy). The
participants were asked to stand on the pressure platform,
in bilateral standing, while looking at a reference point
located 1.8 m above the oor with their arms relaxed at
their sides. When the participants were stable, the data
were recorded. From the footprints obtained, 3 parameters
were calculated using pressure platform software
(Footchecker 4.0): AA, SI, and CSI (eFigure, available at
https://academic.oup.com/ptj). The AA is the angle formed
between the line connecting the most medial points at the
heel and forefoot and the line from the most medial point
of the forefoot to the apex of the concavity of the MLA.30
The SI is obtained by dividing the minimal distance of the
midfoot by the widest section of the rear foot region,18
and the CSI is the ratio of the minimal distance of the
midfoot to the maximal distance of the forefoot.18
The 6 items of the FPI-6 (talar head palpation; supra- and
infralateral maleolar curvature; calcaneal frontal plane
position; prominence in the region of the talonavicular
joint; congruence of the MLA; and abduction/adduction of
the forefoot on the rear foot)24 were evaluated with the
participants in a relaxed bipedal position.
In the correlation study, the measurements were collected
by a physical therapist with more than 6 years of
experience in the use of the measurements.
Data Analysis
The data normality was veried using the
Kolmogorov-Smirnov test. Means and standard deviations
were used for the descriptive analysis of the continuous
variables, and frequencies and percentages were used for
discrete variables. The reliability of the NDT and the
footprint parameters was evaluated using the intraclass
correlation coefcient [ICC(2,1)] and the 95% CI. The
kappa coefcient (κ) was used to evaluate the reliability of
the FPI-6. The ICC was determined by using mixed-effect
and absolute agreement or consistency 2-factor alpha
models. In addition, the standard error of measurement
(SEM) and the minimum detectable change at a 95%
condence level (MDC95) were also calculated. The
following formulas were used to calculate the SEM and the
MCD95:SEM=SD √(1–ICC)31 ;
MDC95 =SEM ×1.96 ×√2.32 Pearson correlation
coefcients (r) were obtained for the NDT relative to each
of the footprint parameters. The correlations between the
FPI-6 and the other measurements were evaluated using
the Spearman correlation coefcient (rs). The ICC was
interpreted as follows: poor reliability (≥0.5), moderate
reliability (0.5–0.75), good reliability (0.75–0.9), and
excellent reliability (≥0.9).33 The interpretation of Landis
and Koch34 was used for the κvalues: poor agreement
(<0); slight agreement (0.00–0.20); fair agreement
(0.21–0.40); moderate agreement (0.41–0.60); substantial
agreement (0.61–0.80); and almost perfect agreement
(0.81–1). Correlations were interpreted as follows: poor
(0–0.39), fair (0.4–0.59), good (0.60–0.74), and excellent
(≥0.75).35 The statistical analysis was conducted using
SPSS 20.0 (IBM SPSS, Chicago, IL), and a Pvalue of <.05
was considered statistically signicant.
Results
Reliability
Twelve women (60%) and 8 men (40%) were included in
the reliability study. All of the MLA variables showed a
normal distribution. Table 1shows the ICC, 95% CI, SEM,
and MCD95 of the NDT and the footprint parameters. Both
intrarater reliability and interrater reliability were excellent
for all of the parameters studied (P<.001), being higher
than 0.9, except for the CSI in interrater time 2
(ICC =0.898). The SEM and the MDC95 were low, giving a
high level of accuracy. The FPI-6 showed almost perfect
agreement for both intrarater reliability (κ=0.872) and
interrater reliability (κ=0.829).
Correlations
Seventy-one participants (24.13 years old [SD =3.41]; 38
women [53.5%] and 33 men [46.5%]) were included in the
correlation study. The mean values were 11.83 mm
(SD =1.68) for the NDT, 25.32 degrees (SD =3.63) for
the AA, 47.43 (SD =8.98) for the SI, and 64.71
(SD =12.49) for the CSI. Figure 1shows the frequencies
of the FPI-6 categories.
Statistically signicant correlations (P<.001) were
obtained between the NDT and the footprint parameters.
Pearson rabsolute values ranged from 0.722 to 0.788. The
correlation between the NDT and the FPI-6 was excellent
(P<.001; rs=0.818), and that between the footprint
parameters and the FPI-6 was good (P<.001;
rs=|0.663–0.703|). The footprint parameters showed an
excellent correlation (P<.001) with each other
(r=|0.901–0.931|). Table 2shows the r, 95% CI, and
coefcients of determination (r2) among all of the outcome
measures. Figures 2through 4show the correlations
between the NDT and the footprint parameters evaluated.
Discussion
Reliability
The reliability and SEM are important elements for the
validity and interpretation of measurements. In our
research, the reliability (both intrarater and interrater) of
all of the measurements was high, making them
satisfactory for clinical use.
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Evaluating the Medial Arch in People With Low Arch
Tab le 1 .
Intraclass Correlation Coefficient (ICC), 95% CI, Standard Error of Measurement (SEM), and Minimum Detectable Change at
95% Confidence Level (MDC95) for the Navicular Drop Test (NDT) and Footprint Parametersa
Reliability Measure RaterorTime ICC 95% CI SEM MDC95
Intrarater NDT Rater 1 0.955b0.886–0.982 0.318 0.883
Rater 2 0.950b0.895–0.976 0.314 0.870
AA Rater 1 0.977b0.941–0.991 0.739 2.048
Rater 2 0.973b0.942–0.987 0.722 2
SI Rater 1 0.972b0.928–0.989 0.585 1.622
Rater 2 0.975b0.947–0.988 0.580 1.608
CSI Rater 1 0.959b0.897–0.984 1.002 2.778
Rater 2 0.946b0.888–0.975 1.043 2.890
Interrater NDT Time 1 0.914b0.795–0.965 0.440 1.220
Time 2 0.919b0.836–0.960 0.442 1.226
AA Time 1 0.954b0.888–0.982 1.045 2.896
Time 2 0.947b0.891–0.976 1.011 2.803
SI Time 1 0.945b0.866–0.978 0.820 2.273
Time 2 0.951b0.899–0.982 0.812 2.251
CSI Time 1 0.921b0.813–0.968 1.391 3.857
Time 2 0.898b0.798–0.950 1.433 3.972
aAA =arch angle; CSI =Chippaux-Smirnak Index; SI =Staheli Index.
bP<.001.
Figure 1.
Frequencies of Foot Posture Index-6 (FPI-6) categories.
The NDT demonstrated excellent intrarater reliability and
interrater reliability, with ICC values higher than 0.9. With
regard to intrarater reliability, rater 1 presented an ICC of
0.955 and rater 2 presented one of 0.950. Various
researchers have demonstrated good to excellent intrarater
reliability in people who were healthy (0.88–0.98),13,27,29
similar to our results. In people who were injured, the
intrarater reliability was good in those with patellofemoral
pain (0.76–0.81),13 excellent in people with anterior
cruciate ligament injury (0.9),36 and moderate to excellent
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Evaluating the Medial Arch in People With Low Arch
Tab le 2 .
Pearson Coefficient Correlation (r), 95% CI, and Coefficient of Determination (r2)a
Measure
AA SI CSI
FPI-6 r(95% CI)
r(95% CI) r2r(95% CI) r2r(95% CI) r2
NDT −0.732 (−0.601 to −0.825)b0.536 0.788 (0.680 to 0.863)b0.622 0.722 (0.588 to 0.818)b0.521 0.818 (0.723 to 0.882)b
AA −0.901 (−0.845 to −0.937)b0.812 −0.930 (−0890 to −0.956)b0.865 −0.663 (−0.509 to −0.776)b
SI 0.931 (0.891 to 0.957)b0.867 0.703 (0.562 to 0.804)b
CSI 0.669 (0.517 to 0.780)b
aAA =arch angle; CSI =Chippaux-Smirnak Index; FPI-6 =Foot Posture Index-6; NDT =Navicular Drop Test; SI =Staheli Index.
bP<.001.
Figure 2.
Correlation between the Navicular Drop Test and the arch angle.
in people with rheumatoid arthritis (0.73–0.98).37 The
interrater reliability obtained in our study was also
excellent, demonstrating lower ICC values than the
intrarater reliability (0.908 and 0.917). Other researchers
previously identied less interrater reliability—moderate
to excellent interrater reliability in people who were
healthy (0.56–0.93)29,37 and people with rheumatoid
arthritis (0.67–0.92)37—and good interrater reliability in
those with patellofemoral pain (0.76–0.81).13 In our
research, the SEM was less than 0.5 mm in all cases; our
values were lower than the SEM obtained in other
studies.29,36,38 An explanation for this result could be that
only participants with a low MLA were included in our
sample, being a homogeneous sample. In addition, the
reliability of the NDT is related to the level of experience
of the testers.29,39 This could be related to the difculty in
locating the navicular tuberosity40 and placing the subtalar
joint in a neutral position.39 In our research, the testers
were trained in the management of the NDT and they
consistently and accurately identied the navicular
tuberosity, and demonstrated consistency in identifying
the subtalar neutral position.
With regard to the reliability of the footprint parameters,
both intrarater reliability and interrater reliability showed
ICC values near to or higher than 0.9. Previous studies
obtained excellent reliability for the SI and the CSI
(0.914–0.998).30,41 However, the reliability of the AA
shown previously ranged from moderate to excellent
(0.605–0.993).30,41,42 These ndings could be related to the
variations in identifying footprint landmarks.41 With
regard to the SEM, our values were low. No previous
studies evaluating the SEM in the footprint parameters
were found.
The FPI-6 also showed almost perfect agreement for both
intrarater reliability and interrater reliability, presenting κ
values higher than 0.8. Previous studies showed excellent
intrarater reliability23,43 and moderate44 to excellent
interrater reliability23,24 ,43 in adults who were healthy, and
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Evaluating the Medial Arch in People With Low Arch
Figure 3.
Correlation between the Navicular Drop Test and the Staheli Index.
Figure 4.
Correlation between the Navicular Drop Test and the Chippaux-Smirnak Index.
excellent interrater reliability in people with
patellofemoral pain syndrome.13 Problems in the type of
the foot have been found previously45,46 and a previous
training in the management of the FPI-6 is recommended
to increase the reliability.24,45 ,47 According to our ndings,
the NDT, AA, SI, CSI, and FPI-6 were reproducible and
showed high reliability in participants with a low MLA.
Correlations
With regard to the principal aim of the study, the
correlations of the NDT, the footprint parameters, and the
FPI-6 in participants with a low MLA were signicant
(P<.001).
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Evaluating the Medial Arch in People With Low Arch
In terms of the correlations between the NDT and the
footprint parameters, the rvalues were higher than 0.7,
and the correlation was good for the AA (r=−0.732) and
the CSI (r=0.722) and excellent (r=0.788) for the SI. To
our knowledge, this is the rst research to evaluate this
relationship. However, the correlations between other
navicular measurements and the footprint parameters have
been studied before. Thus, the correlation between the
navicular height and the AA ranged from poor (r=0.39)42
to fair (r=0.457 to 0.571).30,48 The correlation between
the navicular height and the CSI was fair (r=−0.483 to
0.498),30,48 and the correlation between the navicular
height and the SI ranged from poor (r=0.302)48 to fair
(r=−0.469).30 The correlation increased when
normalized navicular height was used (ranging from 0.619
to 0.645).30 The normalized navicular height is obtained
by dividing the navicular height by the total length of the
foot.49 In the present research, we included only a low
MLA, whereas previous studies30 ,42,48 included a broad
spectrum of MLA heights. Moreover, we did not include
people with a BMI of ≥30 because the body composition
and BMI could inuence the interpretation of the
footprints.50–52
The correlation between the NDT and the AI was also
studied. Billis et al53 obtained, in 26 people, a poor
correlation between the NDT and the AI, both in single-leg
stance AI (r=0.320) and bipedal stance AI (r=0.317).
Nakhaee et al26 found a fair correlation between the NDT
and the AI (r=0.44). The correlations obtained by us
were higher. This could be related to the fact that the AI is
inuenced by the soft tissues53 and the body
composition.51 In our study, there were no people with a
BMI of ≥30, and our sample included only individuals
with a low MLA. In addition, we used footprint parameters
related to the width of the foot, not dependent on the
contact area, such as the AI. Billis et al53 evaluated the
correlation between the NDT and the Valgus Index,
nding values similar to our own (r=0.631–0.657). This
could be explained by the fact that the Valgus Index, like
the footprint parameters studied in this work, does not
depend on the contact area of the foot.
The NDT and the FPI-6 showed an excellent correlation in
our study (rs=0.818). Our research included only
individuals with a low MLA (NDT values of ≥10 mm).
The observed category frequencies of the FPI-6 (Fig. 1)
also fell into ranges that indicated a low MLA.
Menz and Munteanu49 studied the correlations among
several parameters, including the FPI-8, the navicular
height, and the normalized navicular height in older
people, and included a broad spectrum of MLA height.
They obtained rvalues ranging from −0.722 to −0.735.
With regard to the correlations between the FPI-6 and the
footprint parameters, we obtained good correlations
(rs=|0.663–0.703|). We were unable to nd studies that
considered them. The few studies that have evaluated the
correlations between the FPI and the footprint parameters
used the FPI-8. Redmond et al22 compared the FPI-8 and
the Valgus Index, showing that the FPI-8 total scores
predicted 59% of the total variance of the Valgus Index.
Menz and Munteanu49 studied the correlation between the
FPI-8 and the AI in older people, nding a fair correlation
(r=0.424).
The evaluation of the MLA height should be included in
the clinical exploration of the foot posture. The decrease
of the height of the MLA is related to several lower limb
injuries,1,11,13–15 back pain,54 ,55 and foot mobility.56 To our
knowledge, this is the rst research which has evaluated
the correlations of the NDT, the footprint parameters, and
the FPI-6 in people with a low MLA. In our study, the NDT
was well correlated with the footprint parameters and the
FPI-6 in the evaluation of the height of the MLA in people
with a low arch. Therefore, the clinicians can use different
measurements in the study of the MLA in such individuals.
However, the characteristics, advantages, and
disadvantages of these parameters need to be considered.
The NDT had fewer disadvantages than digital footprint
parameters and is an inexpensive method for evaluating
the MLA height. Pressure platforms are expensive and
many clinicians cannot use them in their clinical practice.
An alternative to this could be ink footprints, but they
present several disadvantages, including inaccurate
measurements and difculties in interpreting them.19 In
addition, footprint parameters could be affected by body
composition,50,51 while having no inuence on
measurements of navicular height.57 The FPI is commonly
used to quantify foot posture,22 being correlated to
radiographs,49 as it presents good interval construct
validity.58 The FPI evaluates the foot position using 6 or 8
items, whereas the NDT uses only 2 measurements. In
addition, the NDT is also correlated with radiographs.59
Therefore, clinicians should consider the NDT as the rst
option for examining foot posture in individuals with a
low MLA. The NDT is less time-consuming, has less
opportunity for error (compared with the other forms,
which require multiple measurements), and is highly
correlated with the other options.
Study Limitations
A limitation of the study is that we have not used
radiographic parameters, the gold standard for evaluating
the MLA height.16 A further study including radiographs
may be necessary to validate the NDT, the footprint
parameters, and the FPI-6. We have only evaluated the
dominant foot. However, asymmetries could be found
between the dominant foot and the nondominant foot60
and could affect the results of the research. Another
limitation is that the results of this research were from
individuals who were healthy, and they cannot be
generalized to individuals with normal and high MLAs.
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Evaluating the Medial Arch in People With Low Arch
Especially important is the high MLA, which is a less
exible structure61,62 and which is related to several
injuries.1,11–15 Further research should focus on a higher
MLA.
In addition, the examiner bias needs to be considered. The
NDT is a test related to the level of experience of the
testers29,39 and has shown less reliability in inexpert
raters.29 A previous experience is needed to locate the
navicular tuberosity40 and place the subtalar joint in a
neutral position.39
Conclusion
From our research ndings, in people with a low MLA, the
NDT showed signicant correlations with the footprint
parameters, being moderate for the AA and CSI and
excellent for the SI. In addition, an excellent correlation
was found between the NDT and the FPI-6. All of the
evaluated parameters showed high intrarater reliability
and interrater reliability. We recommend the use of the
NDT as the rst choice for examining foot posture in
individuals with a low MLA.
Author Contributions
Concept/idea/research design: J.C. Zuil-Escobar, C.B. Martínez-Cepa,
J.A. Martín-Urrialde, A. Gómez-Conesa
Writing: J.C. Zuil-Escobar, C.B. Martínez-Cepa, A. Gómez-Conesa
Data collection: J.C. Zuil-Escobar, C.B. Martínez-Cepa, J.A. Martín-Urrialde
Data analysis: J.C. Zuil-Escobar, J.A. Martín-Urrialde, A. Gómez-Conesa
Project management: J.C. Zuil-Escobar, C.B. Martínez-Cepa,
A. Gómez-Conesa
Fund procurement: J.C. Zuil-Escobar
Providing participants: J.C. Zuil-Escobar, J.A. Martín-Urrialde
Providing facilities/equipment: J.C. Zuil-Escobar, C.B. Martínez-Cepa,
J.A. Martín-Urrialde, A. Gómez-Conesa
Providing institutional liaisons: J.C. Zuil-Escobar, A. Gómez-Conesa
Clerical/secretarial support: J.C. Zuil-Escobar, C.B. Martínez-Cepa
Consultation (including review of manuscript before submitting):
J.C. Zuil-Escobar, C.B. Martínez-Cepa, J.A. Martín-Urrialde, A.
Gómez-Conesa
Ethics Approval
The project was approved by the Research Ethics Committee of Centro de
Estudios Universitarios San Pablo University.
Funding
There are no funders to report.
Disclosure
The authors completed the ICJME Form for Disclosure of Potential Conflicts
of Interest. They reported no conflicts of interest.
DOI: 10.1093/ptj/pzy149
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