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Onishi et al. Plast Aesthet Res 2021;8:50 https://dx.doi.org/10.20517/2347-9264.2021.75 Page 3 of 9

(control group). The edema reduction effect was compared between the two groups. This study was
conducted in accordance with the Declaration of Helsinki and was approved by the Institutional Review
Board of Saitama Medical University (#1483) and Tochigi Cancer Center (#21-C004).

Surgical procedure
We performed almost all LVA surgeries under local anesthesia. Three sites for LVA were selected based on
preoperative indocyanine green lymphangiography. After making a 2 cm skin incision, lymphatic vessels
and venules were collected nearby, and a side-to-end anastomosis was performed with an 11-0 nylon
sutures using a surgical microscope. Upon completion of anastomosis, skin closure was performed using a
5-0 monofilament absorbable subcuticular suture. Prophylactic antibiotics were administered on the day of
the surgery. No perioperative anticoagulation therapy was administered to our patients.

Perioperative interventions
Currently, in our clinical practice, we have adopted reduction treatment, including compression therapy
and remedial exercise, in the early postoperative period after LVA since October 2015. Patients underwent
compression therapy and exercised under compression from the first postoperative day. Patients wore
elastic bandages and/or elastic stockings with a target interface pressure of 20-60 mmHg measured by our
lymphedema therapists using the Pico Press® (Microlab, Padua, Italy). Compression was carefully applied
with an even pressure gradient, while avoiding a direct intrusion into the anastomotic sites. The exercise
session consisted of treadmill walking, climbing stairs, and an exercise bike for aerobic exercises as well as
resistance exercises, including calf raising and squatting. Patients were instructed to exercise with an
appropriate intensity, aiming at 3-4 points on the ratings of perceived exertion (modified Borg scale) ,
[14]
namely, moderate to somewhat hard. Specifically, for aerobic exercises, we aimed at an intensity that
patients could continue for 20 min. For resistance exercises, the load was applied at a level that patients
could repeat the exercise 10-20 times without a break. The exercise protocols were adjusted individually to
avoid fatigue and muscle pain on the next day. Patients were discharged on the 7th postoperative day and
instructed to continue compression therapy and exercises at home.

Data collection
We collected clinical data, including age, sex, body mass index (BMI), etiology, previous radiotherapy,
previous LVA, clinical stage, duration of CDT before LVA surgery, institute of treatment, and measured
girth. The clinical stage was based on the classification of the lymph edematous limb set forth by the
[1]
International Society of Lymphology . Girth measurements were performed at five points in the lower
extremity: the foot (C ), ankle (C ), calf (C ), knee (C ), and the thigh (10 cm above the upper border of the
A
F
K
C
patella bone) (C ). Girth measurement data at the first visit, one month before, and one year after LVA
T
surgery were collected. The extremity volume was estimated using the lower extremity lymphedema index
(LEL index) which is given by the formula: LEL index = (C + C + C + C + C )/BMI.
[15]
2
2
2
2
2
F
T
C
K
A
Statistical analysis
Propensity score analysis was conducted to minimize the effects of selection bias and potential confounders.
The propensity score was calculated using a logistic regression model, with the following variables: age,
BMI, sex, etiology, clinical stage, LEL index at the first visit, previous radiotherapy, previous LVA, institute
of treatment, and duration of preoperative CDT. Multiple logistic regression analysis provided each
participant with a propensity score that represented the probability of being treated with PORT following
LVA surgery. The nearest neighbor propensity score matching was used to match participants who were
treated with PORT and without PORT after LVA, at a 1:1 ratio, with a caliper of 0.2. To assess for
differences in demographics and characteristics between the groups before and after matching, we
performed the Wilcoxon rank sum test for continuous data and chi-square or Fisher’s exact test for