Keywords
ankle - radiography - range of motion, articular
Introduction
The measurement of the range of motion of the ankle is now considered of great importance
for diagnosis, therapeutic choice, and follow-up of treatment evolution in patients
with pathologies, both in the ankle and the hindfoot.[1] However, there is no established method of choice for the safe assessment of talocrural
mobility.[1]
[2]
[3] Some authors have published several possibilities for evaluating this movement,
using from traditional goniometers,[4]
[5]
[6] digital goniometers,[3] inclinometers,[5]
[6] applications developed for smartphones,[4] equipment developed specifically for this purpose,[5]
[6] and measurement using radiographs.[7]
[8] Moreover, the movement between the leg and the foot does not occur alone in the
ankle, but in conjunction with the movement of the other joints of the hindfoot and
even the middle and forefoot[1]
[8] (leg-foot movement). According to Thornton et al.,[3] the measurement of this leg-foot movement is more important than the measurement
of ankle movement isolated, because it is this movement (leg-foot) that the patient
perceives and uses on a day-to-day life. Therefore, in the evaluation of the result
of some treatments or surgical procedure, it is the measurement of this movement that
should be used.
With the emergence of arthroplasty for the treatment of ankle arthrosis, the measurement
of the range of motion of this joint gained greater importance, as this would be one
of the theoretical advantages of arthroplasty over arthrodesis.[7]
[8]
[9] As there is no safe method for measuring ankle mobility, the movement between leg
and foot began to be used in this evaluation.[3]
[7]
[9]
[10] Hordyk et al.[8] described a method for the evaluation of ankle arthroplasties, also used by Lisboa
Neto et al.,[11] using radiographic examination in the incidence in profile with load, a film with
the patient performing maximum plantar flexion, another film with maximum dorsiflexion.
The range of motion is determined by measuring the angle between the plantar surface
(ground) and the posterior cortical of the tibia.[8] Lisboa Neto et al.[11] used the longitudinal axis of the distal tibia.[11]
The aim of the present study is to evaluate the methods of measuring leg-foot movement
in normal ankles and feet by comparing the results of clinical measurements (traditional
goniometer, digital goniometer, inclinometer, smartphone inclinometer application)
with those of radiographic measurement to define the best method to be used in daily
practice and determine which leg-foot range is considered normal.
Methods
This study was carried out in the department of orthopedics and traumatology of our
institution and was approved by the ethics committee on research in human beings.
All participants signed the informed consent form (TCLE). The sample consisted of
44 patients aged 18 years or older, totaling 60 feet, attending the outpatient clinic
of this institution. Those with changes in the hip and/or knee joints, movement restriction
in both feet, amputation of one of the limbs, and previous pathologies in the lower
limb to be evaluated were excluded. Adopting a statistical confidence of 95%, the
sample with 60 cases has a power of 0.973 in detecting differences, which we consider
satisfactory for our study.
Participants were submitted to leg-foot movement measurement with: (1) traditional
goniometer; (2) digital goniometer (Digital Angle Ruler 200MM/ Shahe); (3) inclinometer
(Digital Inclinometer/Digital Level); (4) smartphone application (Ratefast Goniometer
v. 1.3/Alchemy Logic Systems, INC) available for IOS and Android platforms; and (5)
profile radiography with maximum flexion and extension of the ankle and foot. We considered
the radiographic method as the gold standard in our study. All measurements were evaluated
with maximum load, plantar flexion, and dorsiflexion without removing the foot from
the ground. The four clinical methods (traditional goniometer - TG, digital goniometer
- DG, inclinometer – In, and application - App) were compared with radiographic measurement
to verify if there was a significant difference between them.
Two researchers evaluated the leg-foot movement three times in each method. The mean
of the obtained values was considered as final measure. For the measurement with the
traditional ([Fig. 1]) and digital ([Fig. 2]) goniometers, as well as with the smartphone application ([Fig. 3]), the ground and the axis of the fibula diaphysis were used as parameters. For the
inclinometer, the landmark was used immediately below the anterior tuberosity of the
tibia ([Fig. 4]). On radiographic examination, the angle between a line perpendicular to the ground
axis and the central axis of the distal tibia was considered to calculate the dorsiflexion
and plantar flexion of leg-foot movement ([Fig. 5]). Maximum dorsiflexion was achieved by asking the patient to take a step forward
with the contralateral foot and perform as much dorsiflexion as possible in the ankle
studied without removing the heel from the ground. For maximum plantar flexion, the
patient was asked to take a step back with the contralateral foot and make as much
plantar flexion as possible without removing the studied forefoot from the groundl9,
[11] ([Fig. 1]).
Fig. 1 Profile foot photographs using the traditional goniometer. We used as parameter the
soil and the fibula dyaphysis, (A) maximum dorsiflexion and (B) maximum plantar flexion.
Fig. 2 Profile foot photographs using the digital goniometer. We used as parameter the soil
and the fibula dyaphysis, (A) maximum dorsiflexion and (B) maximum plantar flexion.
Fig. 3 Photographs of the foot in profile using the smartphone application - aligned with
the axis perpendicular to the ground and the axis of the fibula. (A) maximum dorsiflexion and (B) maximum plantar flexion.
Fig. 4 Photographs of the foot in profile using the inclinometer - positioned just below
the anterior tuberosity of the tibia. (A) maximum dorsiflexion and (B) maximum plantar flexion.
Fig. 5 Radiographs of the foot in profile and with load demonstrating the method of measurement
of joint amplitude. The longitudinal axis of the tibia and a line representing the
soil were marked. (A) maximum dorsiflexion and (B) maximum plantar flexion. Source: Allinger TL, Engsberg JR. A method to determine
the range of motion of the ankle joint complex, in vivo. J Biomech. 1993;26(1):69–76.
For statistical analysis, the following software were used: IBM SPSS Statistics for
Windows Version 20.0 (IBM Corp., Armonk, NY, USA), Minitab 16 and Microsoft Excel
2010 (Microsoft Corp., Redmond, WA, USA). We defined for this study a significance
level of 0.05 (5%). We used the Wilcoxon test to compare the results of the range
of motion obtained by the different measurement methods.
Results
We evaluated 60 feet (44 individuals), 29 right feet and 31 left feet, 36 male and
8 female participants, with a mean age of 36 years old (ranging from 19 to 59 years).
Considering the radiographic measurement as the gold standard, we obtained an average
range of motion between the leg and foot of 65.6 degrees, with a mean plantar flexion
of 34.9 degrees and dorsiflexion of 30.7 degrees. [Table 1] shows the data on range of motion, maximum plantar flexion, and maximum dorsiflexion
obtained with clinical measurement methods. We can observe that in clinical measurements,
the values obtained were lower than those noted in radiographic measurement. After
statistical analysis of these data, we can state that the range of motion of the four
clinical methods was different and lower than the value obtained with radiographic
measurement.
Table 1
|
Average
|
Median
|
P-value
|
|
Total Amplitude
|
RX
|
65.6
|
67
|
- x -
|
|
Traditional
|
61.3
|
61
|
< 0.001
|
|
Digital
|
63.2
|
64
|
0.001
|
|
Inclinometer
|
63.3
|
64
|
0.008
|
|
APP
|
62.7
|
63
|
0.002
|
|
Inflection
|
RX
|
34.9
|
37
|
- x -
|
|
Traditional
|
32.7
|
32
|
< 0.001
|
|
Digital
|
33.4
|
34
|
0.036
|
|
Inclinometer
|
33.4
|
34
|
0.076
|
|
APP
|
32.9
|
33.5
|
0.019
|
|
Extension
|
RX
|
30.7
|
30.5
|
- x -
|
|
Traditional
|
28.5
|
28
|
< 0.001
|
|
Digital
|
29.5
|
30
|
0.040
|
|
Inclinometer
|
29.6
|
30
|
0.103
|
|
APP
|
29.6
|
30
|
0.067
|
When comparing range of motion with only clinical measurement methods (manual goniometer,
digital goniometer, inclinometer, and smartphone app) we noticed that the results
with the manual goniometer were statistically different from the other clinical methods.
The measurements of range of motion obtained with the digital goniometer, smartphone
app, and inclinometer were statistically similar.
Discussion
Although ankle amplitude is considered important both in the diagnosis and in the
follow-up of the treatment of various pathologies involving this region, there is
no standardization in the literature on which method of measurement is best.
The evaluation of isolated talocrural joint is also a matter of controversy. Coetzee
and Castro[7] described a method of radiographic measurement of the range of motion of the talocrural
joint. Although radiography with dorsiflexion was performed with load, radiography
to measure plantar flexion was performed without load, which in our opinion is a bias
in the measurement of range of motion. Russell et al.[12] found differences in the range of motion in the ankle of ballerinas when measured
with and without load. Hordyk et al.[8] measured leg-foot mobility and isolated talocrural joint using radiographs in profile
incidence with load. However, unlike our study, in which we used the longitudinal
axis of the tibia, these authors considered the posterior cortical of the tibia as
tibial axis. This choice was justified, according to the authors, because this parameter
is rarely obstructed on radiography, even in those cases of ankle arthroplasty with
intramedullary nail. In addition to measuring the leg-foot axis, they also measured
the range of motion of the ankle and for this, they traced another axis, considering
the lower joint surface of the talus head and the later point of the posterior facet
of the talocalcaneal articular surface, which, in our opinion, can also lead to measurement
errors due to ankle and foot positioning at the time of radiography and anatomical
variations. Another detail to be considered is that the tibia's posterior cortical
may present alterations resulting from fractures or deformities, which would hinder
the exact design of this axis. Therefore, the axis of the distal tibia as used in
our study would be a measured option with lower probability of errors.
We noticed that the results of ankle range of motion using the radiographic method
(65.6 degrees on average) were higher than those obtained with the other methods and
with a statistically significant difference with all clinical measurements studied
here. Thus, we recommend that this should be the measurement considered in clinical
practice to assess the leg-foot range of motion, and we standardized in our service
this radiographic evaluation for patients with ankle and foot pathologies. We could
not find a clear reason why the radiographic measurement was different from the clinical
measures. Perhaps, because radiography is a complementary examination, patients may
have worked harder at the extremes of the movement, achieving greater range of motion.
When we evaluated the clinical methods, we noticed that they were equivalent, except
for the measurement performed with the traditional goniometer, usually an orthopedist's
pocket instrument. We believe that in addition to the difficulty of reading the result
obtained, the short arms of this instrument and the difficulty to achieve correct
positioning may have interfered in the measurement. Although some authors report similarity
between clinical measurements in the literature,[13] in our study, measurement with the traditional goniometer was inaccurate to determine
the true amplitude of the leg-foot movement. Marcano-Fernandez et al.[14] commented that the traditional goniometer, although widely used in orthopedics,
leads to many measurement errors, and has low reliability. Russell et al.,[12] evaluating ankle mobility in dancers, found different results comparing the traditional
goniometer and the inclinometer. Thornton et al.[3] used a digital goniometer to measure leg-foot movement. They found different values
from ours, with leg-foot range of motion of 79.8 degrees. In our study, the range
of this movement measured on radiography was 65.6 degrees, a difference of 14.2 degrees.
If we consider the measurement of the digital goniometer employed by us, the difference
was even greater. The measurement in our study was 63.2 degrees, and the difference
in the result of the two studies was 16.4 degrees. Thornton et al.[3] used a goniometer with 50 cm arms and 20 cm knots. Considering the longitudinal
axis of the fibula as a parameter, it may be that the longer arm goniometer results
in a more precise measurement. However, this is not the biggest difference between
the two studies. Thornton et al.[3] measured plantar flexion with the patient sitting in a chair, thus eliminating the
effect of weight discharge on the measure, a fact that we considered important. Although
it allows a more comfortable position to the patient in plantar flexion measurement,
the effect of weight discharge can change the functioning of these joints. In addition,
we must remember that these joints work on a day-to-day high with weight discharge.
Therefore, we believe that for a more reliable measure, these measurements should
be carried out with load. When we evaluated the isolated dorsiflexion movement, the
value of 29.6 degrees obtained by Thornton et al.[3] was similar to that obtained in the radiographic study, 30.7 degrees. The great
difference was observed in the plantar flexion values, 51.2 degrees in Thornton's
study and 34.9 degrees in our study. Grimston et al.[15] observed differences in range of motion that they called the ankle joint complex,
according to the age and gender of the patients evaluated. In our study, the mean
age of the patients was 36 years old. According to the study by Grimston et al.,[15] who employed an equipment developed to measure the movement of the ankle complex
(ankle joint and talocalcaneal), the mean range of motion of the ankle joint complex
in this age group would be 74.2 degrees, ranging from 57 degrees to 92 degrees. Also
different from the values we obtained in our study (65.6 degrees).
The goniometer is a low-cost instrument widely used in clinical practice. The traditional,
with shorter rods, requires greater training and attention from the evaluator both
for the correct positioning of the rotation fulcrum and alignment of the arms of the
instrument with the correct axes and reference points. The digital version that we
used in this study has longer arms (20 cm), which facilitates better alignment with
the leg and foot axes and allows the measurement to be more accurate. Thus, it is
not necessary to adjust the visual field of the examiner to write down the exact measurement.
Although the digital inclinometer was used in some articles[5]
[6] as a measure of the ankle range of motion and its measurement is statistically similar
to the other clinical methods used in this study, except the traditional goniometer,
in our opinion, its correct use is technically more difficult. Its correct positioning
with the tibial tuberosity is not always easy and requires care and attention on the
part of the examiner, which can lead to measurement errors. For this reason, we do
not recommend this method in the day-to-day of the office, due to greater technical
difficulty to obtain the results. Smartphone apps are available and can assist in
the measurement of range of motion. Wang et al.[4] compared three applications available with the traditional goniometer and did not
find statistically significant differences. However, our results discourage the use
of the traditional goniometer as a benchmark. The application used in this study did
not show statistical difference with the other clinical methods, but there was a significant
difference from the result obtained on radiography, and, for this reason, we did not
use it routinely.
This study has limitations. Clinical measurements were performed simultaneously in
all patients. There was no pretest, simulating and mesuring the movement, so that
patients could become familiar with the method. The radiographic measurement was performed
at a different time, after clinical measurement, and there was no randomization or
draw of the sequence of the methods employed, which can also be considered a bias
of the work. However, clinical measurements made at the same time, guarantee a better
fidelity to the result. It was not possible to perform clinical measurements in the
radiographic examination room, because the delay could cause delays in the care of
patients who require the examination. The researchers were not blinded to the results
of the clinical measures applied just before, which can also be considered a bias.
Despite the several articles that employ clinical measurement of ankle range of motion,
we believe, based on the results of this study, that the best evaluation method is
the radiographic one. Therefore, we introduced the radiographic examination in profile
with maximum plantar flexion and maximum dorsiflexion routinely at our outpatient
clinic. We also believe that the isolated measurement of the movement of the talocrural
joint is difficult to evaluate in daily clinical practice and recommend the use of
leg-foot range of motion.
Conclusions
The most appropriate method for the evaluation of leg-foot range of motion is radiographic.
The traditional goniometer proved to be the most imprecise clinical method in this
study. The mean leg-foot range of motion in healthy young adults was 65 degrees.
