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Marshall et al. | Journal of Clinical and Translational Research 2024; 10(5): 296-306 299
maximum voluntary isometric contraction (MVIC) using an WOMAC pain sub-score includes five questions, each scored as 0
electromechanical dynamometer (HUMAC NORM; CSMi, (none), 1 (mild), 2 (moderate), 3 (severe), or 4 (extreme). The total
USA) at 60° of knee flexion. To ensure maximal strength was pain sub-score ranges from 0 to 20, with a lower score indicating
recorded, testing was repeated, with 1 min rest between trials, less pain.
until the readings from two trials were within 5% of each other.
The trial with the highest torque was utilized for data analysis, 2.4. Power and sample size
after normalization [45]. Data were collected with a BIOPAC A large effect size (ES) (>1.0) was found for DCG on
Data Acquisition System (Biodex Medical Systems Inc, USA) swelling compared to controls without an inelastic compression
at 2000 samples/s and analyzed with Acknowledge software, garment [36]. The anticipated ES of ICG on swelling compared
version 5.0 (Biodex Medical Systems Inc, USA). Voluntary to DCG was unknown, but we believed that it would be at least
activation of the quadriceps was assessed using the doublet 0.3. Given this anticipated ES (>0.3), 80% power, and type I error
interpolation technique, where a supramaximal stimulus is rate of 0.05, Whitehead et al. [48] recommended a minimum
applied (Grass S48 stimulator and SIU8T stimulus isolation unit, of 10 participants per cohort in a pilot study to more precisely
Grass Instruments Co, USA) during quadriceps MVIC testing estimate the variability of a treatment effect. Therefore, we set
and again immediately afterward while the muscle is at rest [45]. our minimum sample size for ICG to 10 participants.
Stimulus parameters were two pulses, a pulse duration of 600 µs,
and a frequency of 100 pulses/s. Full voluntary activation of the 2.5. Data analysis
quadriceps is 100%, whereas anything less than this represents The ICG and DCG groups were compared at baseline for
an activation deficit. As this laboratory assessment of quadriceps age, BMI, swelling, quadriceps strength and activation, and
activation is not feasible early after surgery, the quadriceps WOMAC pain using the Wilcoxon rank sum test. The differences
activation battery (QAB) was conducted on day 4 [46]. The between all post-operative time points and baseline were
QAB consists of the following three clinical tests, each scored calculated for the same outcomes and assessed for normality
from 0 to 2: Isometric quadriceps contraction, straight leg raise, statistically using the Shapiro–Wilk test and visually using
and quadriceps extension lag. Isometric quadriceps contraction histograms. Initial efficacy for ICG was assessed with Hedges’
was tested with the participant in supine and the surgical knee g ES for total limb swelling, quadriceps strength, quadriceps
in full available extension ROM. It was scored as 0 (unable to activation, and WOMAC pain. ESs were classified as small if g
initiate any contraction), 1 (poor contraction with no superior ≤0.2, as medium if 0.21 ≤ g ≤ 0.79, or as large if g ≥0.8 [49]. The
patellar movement), or 2 (strong contraction with visible proportion of participants in each group scoring ≤ 3 and ≥ 4 on
superior movement of the patella). Straight leg raise was tested
with the participant in supine, the surgical knee in full available the QAB were compared using Fisher’s exact test.
extension ROM, and the contralateral knee bent to 90°. It was 3. Results
scored as 0 (unable to lift the heel off the table), 1 (able to lift
the heel two feet off the table, but unable to maintain knee in full Participant baseline characteristics can be found in Table 1.
available extension ROM), or 2 (able to lift the heel off the table A total of 14 participants were enrolled in the ICG protocol
and maintain the knee in full available extension ROM). The (62.3 ± 8.3 years; nine females). One participant self-selected
quadriceps extension lag was tested with the participant sitting to wear the garment only while sleeping during the third post-
upright at the edge of a table. The surgical knee was passively operative week due to claustrophobia. An additional participant
extended by the tester to <5° the available extension ROM. The was instructed by a non-study provider during the third post-
participant was then instructed to hold this position while the operative week to only wear the garment while sleeping due
tester withdrew support. It was scored as 0 (unable to keep the to poor ROM progress. Therefore, the data from days 21 and
surgical knee from bending without tester support), 1 (able to 42 were not included in the analysis for these two participants.
maintain knee extension but for <1 s and able to slow the leg’s Finally, one participant was removed from the study during the
descent into further flexion without tester support), or 2 (able to second post-operative week due to deep vein thrombosis (DVT),
maintain knee in extension for >1 s). The total score is the sum of resulting in no data available for days 14, 21, and 42. There
the three tests ranging from 0 to 6. Scoring ≤ 3 on the QAB 4 days were 16 participants in the DCG group (64.7 ± 7.1; 12 females).
after surgery is significantly related to: (i) poorer quadriceps No significant differences were found between groups at
activation 1 month after surgery; and (ii) poorer strength and baseline for age, BMI, swelling, or quadriceps strength (Table 1).
functional performance 1 – 2 months after surgery [46]. ICG had statistically significantly lower quadriceps activation
than DCG at baseline with median values of 57.9% and 84.6%,
2.3.6. Pain respectively (p = 0.01). The ICG group also had statistically
The Western Ontario and McMaster Universities Osteoarthritis significantly higher WOMAC pain than DCG at baseline with
Index (WOMAC) is one of the most commonly utilized patient- median values of 9.0 and 7.5, respectively (p = 0.03).
reported outcome measures after TKA [47]. It can assess three 3.1. Feasibility of ICG
components of TKA recovery: pain, stiffness, and function. In
this study, the self-reported pain of the surgical knee was assessed In addition to the DVT reported above, it should be noted that
using the WOMAC pain sub-score on days 14, 21, and 42. The the two participants who wore the garment during sleeping hours

DOI: http://doi.org/10.36922/jctr.24.00026