2019 IEEE 1st Global Conference on Life Sciences and Technologies (LifeTech 2019)

Patient Simulation: Handrail Position for Knee-OA
Patients Considering Physical Burden and Stability
Chongyang QIU∗ , Shogo OKAMOTO∗ , Naomi YAMADA† , Yasuhiro AKIYAMA∗ , and Yoji YAMADA∗∗

Graduate School of Engineering, Nagoya University, Nagoya, Japan†
Aichi Medecal College, Kiyosu, Japan

Abstract—Knee pain during motions remarkably reduces thequality of life in knee osteoarthritis (OA) patients. The use ofhandrails can help them relieve the pain when standing up
from a chair. This study investigated which handrail position
such as at the affected or non-affected sides is more effective in
reducing the physical burden on the impaired knee, as well as
providing a better stability during a sit-to-stand (STS) motion.
Healthy individuals simulated the typical STS motion of knee OA
patients for avoiding the ethical concerns regarding the pain thata patient may undergo during the experiment. Results obtained
from the patient simulation under controlled conditions revealed
that positioning a handrail at the affected side reduces kneeburden and improves stability.
Index Terms—patient simulation, handrail, flexion-extension
moment, COP

Height-adjustable handrail(chair + 400 mm)

Force sensor

Goniometer

350 mmForce sensing shoes
Fig. 1. Experimental setting

I. I NTRODUCTION
An increasing number of patients are being affected byknee osteoarthritis (OA) in recent years. The risk of knee
OA generally increases with age, and it causes pain in theaffected knees during daily activities, such as STS and walking
motions. Using a handrail, patients can distinctly reduce thephysical burden on the impaired knee and, thus, can get relief
from the pain. There have been some studies about the suitableconditions of handrail use [1], [2]; however, thus far, only afew studies have been done to investigate the distinctive effects
of different handrail positions, such as at the affected or nonaffected sides, in patients with unilateral knee pain. Therefore,
this study investigated the effects of positioning a handrail atthe side of affected-limb or non-affected-limb on STS motions.
A reduction in physical burden on the affected knee and thestability during motion were adopted as the evaluation criteria.
Compared with healthy people, knee OA patients adopt different postures to avoid motions that cause knee pains. However,there is an ethical issue concerning the participation of actual
knee OA patients in the experiments. Because of the possibilityof experiencing pain during motions, it is not ethically correct
to involve knee OA patients in experiments that involve anumber of knee motions under various conditions. Thus, it isof significance that healthy people simulate the typical motionof knee OA patients to provide sufficient data for developing
care facilities, devices, etc. For simulating the motions ofknee OA patients, Yamakawa et al. [3] utilized a pain-warning
electrical stimulation wherein a change in strength according
to the magnitude of knee moment was used as an indicatorof the pain to obtain a more convincing patient simulation.
However, they focused only on the reduction in knee burden

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Height-adjustablechair (as high as
the participants'knees)to discuss the position of handrails, which was not sufficient
to reach a comprehensive conclusion. In the present study,
the stability during STS motions was also considered as asignificant index.
II. E XPERIMENT
A. Participants
Two healthy male university students (participant 1: height 173 cm, weight - 62 kg; participant 2: height - 175 cm, weight- 57 kg) participated in this study. They were not aware of theobjectives of the study.
B. Apparatus
Two force sensors (PFS055YA251G6, Leptrino, Japan) were
installed on the handrail to obtain the vertical handrail reaction
force (vHRF). Three load cells (FX1901, TE Connectivity,USA) were placed on each shoe to measure the verticalground reaction force (vGRF). In addition, the center ofpressure (COP) on the base of support was calculated. A
pressure sensitive film (FSR-406, Interlink Electronics, USA)was placed under the chair for obtaining the timing of seat-off.
The experimental apparatus is shown in Fig. 1.
C. Patient Simulation
Before the main trials, the participants received short lectures on the motion of knee OA patients. Knee OA patientstend to perform a STS motion in more than 3 s due to the knee
pain [4]. For reducing the physical burden on the impairedknee, additional weight (approximately 10%) can be put on

12Fig. 2. Ratio of the peak value of knee extension-flexion moment to bodyweight. Asterisks ** and *** indicate significance levels of 0.01 and 0.001,
respectively.

the contralateral limb [4]. Moreover, a slight lateral trunk lean
toward the non-affected side is typically observed during themotion. Healthy participants were informed of these features
and then allowed to practice the typical motion of the patients
until they became familiar.
D. Settings
Each participant sat on an adjustable chair and the seat wasadjusted to the height of the participant’s knee joints. The
height of the handrail was set 400 mm above the seat andthe distance between the handrail and center of the body was
350 mm. With respect to the distance between two feet, norestriction was set as long as it was within the width of theparticipant’s shoulders. To reduce the influence of the arm, thehand at the no-handrail side was placed on the iliac crest.
E. Tasks
Each participant simulated the STS motions of the patientwith left and right unilateral knee OA. They performed theSTS motions under three conditions: without handrail; handrail
positioned at the non-affected side; and handrail positioned
at the affected side. For each condition, trails were repeatedthirty times. Hence, a total of 180 trials (three conditions ×
two laterality conditions × thirty repetition) were performedby each participant.
F. Data Analysis
Under each condition, trials with the loading symmetry
ratios (the ratio of the mean vGRF on the affected limb tothat on the non-affected limb) beyond the range of mean ±standard deviation reported in [5] were excluded. The dataof the duration between seat-off and standing position wereused for the analysis. The internal flexion-extension moment
working on the knee joint, which is often regarded as areflection of burden [2], and the lateral offset of the COP,
which serves as a stability index, were calculated and analyzed.
Considering the small sample size, the statistical tests wereconducted using each participant’s data.

Fig. 3. Lateral offset of the COP from the center of two feet towards thehandrail. For the case without the handrail, the non-affected side is the positive
direction. Asterisks ** and *** indicate significance levels of 0.01 and 0.001,respectively.

III. R ESULTS
As shown in Fig. 2, after using a handrail, there was a
distinct reduction in the knee extension-flexion moment in boththe participants. Moreover, compared with the handrail at thenon-affected side, the handrail at the affected side resulted
in a reduction in knee moment, indicating a lesser amount ofphysical burden during the STS motion (Participant 1: t(18) =4.23, p < 0.001; Participant 2: t(16) = 4.79, p < 0.001).
Regarding the lateral offset of the COP (see Fig. 3), performinga STS motion with the handrail at the non-affected side led to asignificantly higher offset from the center of the two feet thanthat at the affected side, which resulted in a relative instability.
IV. C ONCLUSIONSThis study involved simulated patients to investigate whichis the effective side of positioning a handrail to reduce kneeburdens and maintain stability during STS motions. Aftertraining, two participants simulated the typical STS motionof knee OA patients and consistently revealed that positioninga handrail at the affected-limb side is advantageous in termsof reducing physical burdens and maintaining stability.
R EFERENCES[1] S. Kinoshita, R. Kiyama, and Y. Yoshimoto, “Effect of handrail heighton sit-to-stand movement,” PloS one, vol. 10, no. 7, p. e0133747, 2015.
[2] S. Kinoshita, “Handrail position and shape that best facilitate sit-to-standmovement,” Journal of back and musculoskeletal rehabilitation, vol. 25,
no. 1, pp. 33–45, 2012.
[3] K. Yamakawa, S. Okamoto, R. Kubo, N. Yamada, Y. Akiyama, andY. Yamada, “Knee pain patient simulation for recommendation of sit-tostand handrail positions,” IEEE Transactions on Human Machine Systems,
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[4] K. Turcot, S. Armand, D. Fritschy, P. Hoffmeyer, and D. Suv, “Sit-tostand alterations in advanced knee osteoarthritis,” Gait & Posture, vol. 36,
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[5] C. L. Christiansen and J. E. Stevens-Lapsley, “Weight-bearing asymmetry
in relation to measures of impairment and functional mobility for people
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