Foot & Ankle International - July 2018 - 831

831

Naraghi et al
Table 2. Interspaces Affected in Subjects With Morton's
Neuroma.
Interspace

Right Foot

Left Foot

Both Feet

Total

2/3
3/4
Both
Total

11
8
2
21 (40.4%)

4
10
8
22 (42.3%)

6
1
2
9 (17.3%)

21 (40.4%)
19 (36.5%)
12 (23.1%)
52 (100%)

any proximal nerve entrapment at the level of the ankle,
knee, hip or back; any history of significant trauma to the
forefoot area; rigid toe deformities; and an inability to
ambulate without pain.
There were no significant differences in age, weight,
height, and body mass index between patients with MN and
control subjects (Table 1). The numbers of affected interspaces with MN are summarized in Table 2.

Measurements
Dynamic peak plantar pressure, contact time, pressure-time
integral, and geometric data were extracted using the
EMED-X platform, which was set flush to the floor within
a 10-m walkway. The EMED-X platform is composed of
6080 capacitive sensors within a sensing area of 475 × 320
mm (sensor resolution, 4 sensors/cm2) and had a pressure
range of 10 to 1,270 kPa, accuracy of ±5%, and hysteresis <
3%.32 The sampling frequency was 100 Hz. A 2-step
approach at a self-selected speed was used for all trials,
which has been demonstrated previously to be as reliable as
the midgait approach.8 Participants stood on the platform
barefoot and took 2 steps forward to determine the starting
position. At the starting position, subjects were instructed to
strike the platform on their second step. Subjects were
instructed to use their usual gait while looking straight
ahead and to avoid targeting the platform. Subjects practiced walking across the platform until they were comfortable with the procedure. Subjects performed 5 trials with
the right and left feet, until a total of 10 successful steps
were recorded. A trial was successful when only 1 foot contacted the platform, contact was made on the second step,
and participants did not target the platform. Trials not meeting these criteria were excluded.
EMED-generated data were analyzed using Novel
Database medical software program version 15.2.3. All
measurements were calculated from the maximum pressure picture of the step during gait, which corresponds to
the contact or push-off phase of gait. The maximum pressure picture is a color-coded image of the foot that represents the maximum pressure value recorded by each sensor.
The foot was divided into 10 regions (masks) using EMED
Automask software. Masks for heel, midfoot, first to fifth
metatarsal heads, hallux, second toe, and third to fifth toes

Figure 1. Ten mask areas depicted for peak pressure and
pressure-time integral measurements.

(Figure 1) were used for analysis. For each mask, peak
pressure (kPa) and contact time (ms) were measured. The
pressure-time integrals (kPa · ms) under metatarsals 2 to 4
were measured to assess the cumulative effect of both pressure and time on MN formation. For each subject, means of
the 5 measurements were used for statistical analyses. Five
geometric measurements that included forefoot width
(cm), foot length (cm), coefficient of spreading (forefoot
width/foot length), foot progression angle (the angle
between the axis of the foot and line of progression), and
arch index (midfoot area divided by total foot area) were
automatically calculated using the software algorithms for
each trial.

Statistical Analysis
All data were explored for normality prior to inferential
analysis. Differences in peak pressure, contact time, pressure-time integral, and geometric data between participants
with and those without MN were determined using independent-samples t tests. Retrospective power calculations

Table of Contents for the Digital Edition of Foot & Ankle International - July 2018