Journal of Rehabilitation Medicine 51-1CompleteIssue | Page 59

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M. Banky et al.
version 1.8.0 (NaturalPoint, Inc., Corvallis, OR, USA) was
used to capture the data and label the markers. Data was then
exported into a customised programme designed for this pro-
ject using LabVIEW 2014 (National Instruments, Austin, TX
USA) software. This software enabled the start- and end-point
of the trial to be selected and was able to quantify joint angles
and the velocity of movement using trigonometry. The testing
velocity was quantified using joint angular velocity in degrees
per second. Once saved, the peak angular velocity, joint start
angle, joint end angle and total ROM for each joint movement
was exported into a database to be used for analysis.
Statistical analysis
To assess absolute inter-rater variability, the mean absolute
differences (MADs) between any 2 measurements of joint start
angle, joint end angle, total ROM and peak testing velocity
which were obtained by the different assessors were calculated.
To assess absolute intra-rater variability, the MADs between any
2 measurements of joint start angle, joint end angle, total ROM
and peak testing velocity which were obtained by the same as-
sessor were calculated (24). Hence, all estimates of the MADs
were expressed in the same units as the measurement-of-interest.
To compute 95% confidence interval (95% CI) for all MADs, a
percentile bootstrapping technique over 500 iterations was used
(25). All inter- and intra-rater variability analyses were done
in R, version 3.4.4 (R Foundation, Vienna, Austria), using the
functions written by Zhouwen Liu (available at http://biostat.
mc.vanderbilt.edu/wiki/Main/AnalysisOfObserverVariability).
In addition, the MAD expressed as a percentage difference of
the mean variable value was calculated for each muscle group
for the primary testing parameter, peak testing velocity. This
enabled further reporting of the variability in testing speeds
between muscle groups. The MAD expressed as a percentage
difference of the mean variable value was not calculated for joint
angles, as each muscle group had a distinctly different start- and
end-point, which did not enable comparison. For example, if
the gastrocnemius has a mean end angle of 10° dorsiflexion and
a MAD of 5°, the MAD would correspond 50% of the mean
variable value. Whereas, if the quadriceps also had a MAD of
5°, but a mean end angle of 130° knee flexion, the MAD would
correspond to only 3.8% of the mean variable value. As such,
the percentages for joint angles would not be representative of
true variability when comparing the muscle groups.
Table II. Participant demographics
Patients (n  = 35)
Diagnosis, n
Stroke
Traumatic brain injury
Central nervous system tumour
Multiple sclerosis
Cerebro-vasculitis
Age, years mean (range)
Sex, n
Male
Female
Height, cm, mean (SD)
Weight, kg, mean (SD)
Lower limb assessed, n
Left
Right
Months since diagnosis, mean (range)
15
13
4
2
1
51.2 (19–85)
22
13
169.8 (9.3)
79.4 (13.76)
18
17
69.9 (1–380)
remaining 4 assessors reported using the MAS as their
most frequently used clinical scale of spasticity.
Inter-rater and intra-rater variability
Table III outlines the mean value across all 35 par-
ticipants, the MADs with 95% CIs and the MAD
as a percentage of the mean variable value for each
muscle group, testing speed (V1 and V3) and testing
parameter (start angle, end angle, total ROM and peak
testing velocity) as a measure of both intra-rater and
inter-rater variability.
Variability of testing velocity. For all measurements the
inter-rater MAD was greater than the intra-rater MAD.
These results (Table III) highlight the large variability
in V3 testing velocity across a cohort of experienced
assessors, especially at the ankle joint. However, as
clinical decision-making is primarily based on the
results of the V3 trials, the V1 results do not have the
same degree of clinical importance as the V3 findings.
Group 1: Patients with a neurological condition. Table
II outlines the demographics of the 35 patients with a
neurological condition who were recruited to partici-
pate in this study. Variability of joint end angle. Joint end angle during
V3 represented the R1 value, or the angle of muscle
reaction when the affected limb was moved “as fast
as possible”. As this is an important component of a
clinical spasticity assessment it was considered the
focus of the secondary aim. Similar to peak testing
velocity, the inter-rater variability was higher than
the intra-rater variability across all 5 muscle groups
for joint end angle.
Group 2: Experienced assessors. Thirty-four ex-
perienced assessors were recruited, including re-
habilitation physiotherapists (n = 26), rehabilitation
consultants (n = 5), acute physiotherapists (n = 2) and
a rehabilitation registrar (n = 1). The assessors had a
mean of 14.3 (range 4–40) years of experience. Thirty
assessors reported the Tardieu Scale or MTS as their
most frequently used clinical scale of spasticity. The Variability of joint start angle. When analysing joint
start angle, results were similar for both the V1 and
V3 trials. Unlike testing velocity and joint end angle,
there was only a small difference between inter- and
intra-rater variability for gastrocnemius, soleus and
quadriceps trials. However, the hamstrings trials at
both 40° and 90° hip flexion demonstrated a similar
pattern to testing velocity and end angle, with the inter-
RESULTS
Demographics
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