Introduction
Little is known about musculoskeletal disorders (MSDs) among endoscopists performing
fluoroscopic procedures. Fluoroscopy-related MSDs can result from persistent static
muscle contraction due to the constrained work conditions. Radiation personal protective
equipment (RPPE), including lead aprons, thyroid collars, and lead glasses, imposes
an additional load. Some reports have described high MSD levels in endoscopists performing
fluoroscopic procedures [1]
[2], but the physical workloads have seldom been quantified. To prevent MSD, it is essential
to optimize the monitor size, height, and distance [3]
[4] and the height of the treatment bed [4]. However, the introduction of new hardware configurations is not feasible because
of high cost. We devised a simple, no-cost countermeasure (the “practical load-on-the-shoulders
releasing technique” [PoRT]; the details are given later) based on intermittent work-rest
periods during fluoroscopic endoscopic treatment. The aim of this study was to investigate
whether PoRT reduces muscular discomfort in endoscopists and to identify the postural
features that may contribute to MSDs during endoscopic procedures.
Methods
Muscular discomfort involving the neck/shoulders, lower back, and lower limbs was
assessed by 25 repeated visual analogue scale (VAS) measurements taken at four time
points during work days (9:00, 12:00, 15:00, 18:00) from June 25, 2020 through October
15, 2020. Tuesday and Thursday are the procedural days in our institution. Therefore,
we collected extensive information on both days. A senior endoscopist (a 41-year-old
man with no comorbidities) was studied. His body mass index was 20.0 kg/m2 and he exercised twice weekly. We studied five conditions, as follows: (1) no breaks;
(2) micro-break every 20 minutes; (3) micro-break every 40 minutes; (4) micro-break
every 20 minutes with PoRT; and (5) micro-break every 40 minutes with PoRT. A micro-break
was defined as less than 1 minute of rest ([Fig. 1]). During the fluoroscopic procedures, operator pitch (the angle when bending forward
or backward) and roll (the lateral angle) were measured using a wearable accelerometer
that estimated head/neck and trunk posture in the sagittal and frontal planes. The
study was approved by the Institutional Review Board of Nagoya City University (approval
no. 46–20–0003).
Fig. 1 The five experimental conditions.
Muscular discomfort evaluation
VAS was used to evaluate muscle fatigue at four time points during the day. Therefore,
the participant wore the RPPE from 9:00 to 18:00 (thus, for the entire workday) and
was asked to indicate pain in his neck/shoulders, lower back, and lower limbs by marking
horizontal lines on a 100-mm VAS (no pain, 0 mm; the most severe pain imaginable,
100 mm).
Intervention details
The five conditions mentioned above were assessed. A micro-break was defined as a
rest period of less than 1 minute while still wearing the RPPE. While performing the
PoRT, the participant personally lifted the lead apron from his shoulders while taking
a micro-break in the sitting position. Working conditions were recorded throughout
the entire observational period.
Measurement of head and trunk angles
Head and trunk angles were determined using the wearable accelerometers. Head angles
were estimated with the aid of JINS MEME motion-sensing eyewear (JINS, Tokyo, Japan);
this measures head motion in three dimensions. The pitch (head angle when bending
forward or backward) and roll (head angle when bending laterally) were recorded. The
front-facing standing position was defined as 0° for each axis. Trunk angles were
estimated using a device worn at the waist (Sensingwear SS-05; Nikon, Tokyo, Japan).
The device was used to measure pitch in the sagittal plane and roll in the frontal
plane. Both motion-sensing devices yield time-series data at 20 Hz. We recorded the
times of all endoscopic procedures and extracted the results.
Sample size and statistical analysis
The sample size was determined based on a previous study [5]. Given the effect sizes of the conditions (five levels, f = 0.25) and times (four levels, f = 0.4), and assuming α = 0.05, we estimated that a statistical power (1 − β) of at
least 80 % could be achieved by including five samples in each cell (25 repeated measurements
under the five conditions). We thus performed two-way repeated-measures analysis of
variance with condition and time as the independent variables. Data processing and
analyses were conducted with the aid of R software (version 3.6.3; R Foundation for
Statistical Computing, Vienna, Austria).
Results
The median number of daily endoscopic procedures was eight (range 5–13). Muscular
discomfort in the neck/shoulders increased over time (F [3,60] = 433.68, P < 0.001) but at 18:00 there was less discomfort with than without PoRT (P < 0.01). The interaction between condition and time was significant (F [12,60] = 16.77,
P < 0.001) ([Fig. 2]). Similar muscular discomfort trends were observed for the lower back (condition:
F [4,20] = 21.8, P < 0.001, time: F [3,60] = 365.4, P < 0.001, condition × time interaction: F [12,60] = 14.4, P < 0.001) and lower limbs (condition: F [4,20] = 12.15, P < 0.001, time: F [3,60] = 275.5, P < 0.001, interaction: F [12,60] = 11.8, P < 0.001).
Fig. 2 Subjective muscular discomfort in the neck/shoulders under the PoRT and non-PoRT conditions
during fluoroscopy procedures. There was a main effect of time on muscular discomfort
(F [3,60] = 433.68, P < 0.001). Discomfort was lower in the PoRT compared to non-PoRT condition (P < 0.001). The condition × time interaction effect was significant (F [12, 60] = 16.77,
P < 0.001).
The head flexion angle was significantly closer to the neutral position under the
PoRT than the non-PoRT condition (P = 0.012, [Fig. 3a]). Displacement of the head pitch/roll angles, defined as the mean square displacement
and based on the average angular change between angle (t + 1) and angle (t), increased significantly with time under both the PoRT and non-PoRT conditions (both
P < 0.001, [Fig. 3b], [Fig. 3d]). The differences between the two conditions with respect to head roll angle ([Fig. 3c]) and the mean trunk pitch/roll angles were not significant ([Fig. 4a], [Fig. 4c]). However, the trunk roll in the PoRT condition was significantly higher than that
in the non-PoRT condition (P = 0.005, [Fig. 4d]). Pitch displacement tended to be constant under the PoRT condition but increased
with time under the non-PoRT condition (condition × time interaction: P = 0.01, [Fig. 4b]). The main effects of condition and time, and the interaction effect, were statistically
significant with respect to roll displacement ([Fig. 4d]).
Fig. 3 Head flexion angle: difference between the PoRT and non-PoRT conditions during fluoroscopy
procedures. a, c Mean angle. b, d Mean displacement. Error bars represent standard deviation.
Fig. 4 Trunk flexion angle: difference between the PoRT and non-PoRT conditions during fluoroscopy
procedures. a, c Mean angle. b, d Mean displacement. Error bars represent the standard deviation.
Discussion
PoRT performed during fluoroscopic endoscopic treatment reduced muscular discomfort
in the neck/shoulders, lower back, and lower limbs, and helped keep the head angle
at the ideal neutral position of ~0°. However, it had no effect on trunk flexion or
the lateral bending posture ([Fig. 3a], [Fig. 3c]). On the other hand, only the trunk roll was higher under the PoRT condition than
under the non-PoRT condition. Lateral bending during procedures may be more fatiguing
than maintaining a neutral trunk angle. Postural dynamics and shifts are good indicators
of discomfort [5]
[6]
[7]. With greater accumulation of fatigue, displacement increases, indicating that the
extent of displacement reflects attempts to alleviate discomfort or fatigue. This
may explain why PoRT was effective in attenuating the development of discomfort in
the neck/shoulders, lower back, and lower limbs, and promoted the maintenance of good
neutral posture. Our simple, no-cost intervention involving control of the work-rest
schedule (PoRT) may reduce MSDs in medical workers but cannot completely eliminate
discomfort that has accumulated over time.
Endoscopic procedures have become increasingly complex and time-consuming. Higher
procedural volumes and more years of endoscopy are associated with higher rates of
work-related injuries [2]. The PoRT is a simple and inexpensive countermeasure that may help prevent MSDs
by promoting an effective work-rest schedule. A previous study [8] on visual display terminal operators showed that 15-minute work times followed by
micro-breaks increased their speed, accuracy, and performance and reduced MSDs. For
endoscopists, micro-breaks alone did not reduce MSDs, but they did so in combination
with the PoRT. Our results indicate that the PoRT reduces subjective muscular discomfort
and improves posture during the performance of fluoroscopic endoscopy, and thus, may
enable more efficient work.
The limitations of our study included the fact that, to test the benefits of PoRT,
the participant wore RPPE for 9 hours consecutively each day. In addition, this study
was conducted in a single center under the management of an occupational health specialist.
Further, the daily procedural numbers varied. Our study design was single-arm and
within-subject, and hence not a randomized controlled trial (RCT). Blinding was impossible.
Thus, our evidence is limited to the intra-rater effects of intervention under unblinded
conditions. Large-scale, multicenter RCTs are required to confirm that PoRT alleviates
MSDs.
Conclusions
In conclusion, periodic microbreaks involving PoRT can reduce subjective MSD in endoscopists
and personnel assisting fluoroscopic procedures. By applying ergonomic measures such
as PoRT, medical workers may be less likely to suffer from MSDs.
