Development and evaluation of a system to assess the effect of footwear on the in shoe plantar pressure and shear during gait
ROBOMECH Journal
Development and evaluation of a system to assess the effect of footwear on the in shoe plantar pressure and shear during gait
Manabu Takano 0
Hiroshi Noguchi 0
Makoto Oe 2
Hiromi Sanada 1
Taketoshi Mori 0
0 Department of Life Support Technology (Molten), Graduate School of Medicine, The University of Tokyo , Tokyo , Japan
1 Department of Gerontological Nursing/ Wound Care Management, Graduate School of Medicine, The University of Tokyo , Tokyo , Japan
2 Department of Advanced Nursing Technology, Graduate School of Medicine, The University of Tokyo , Tokyo , Japan
In this paper, we propose a system to assess the effect of footwear on the in-shoe plantar pressure and shear during gait. In our previous study, we developed a system for measuring the plantar pressure and shear inside footwear using specialized shoes and insoles with sensors. In this study, based on the previous study, 1) we realized a method to measure directly the in-shoe plantar pressure and shear applied from footwear, 2) verified the validity and reliability of the method and 3) evaluated the ability of the system to assess the effect of footwear by measurements with multiple subjects and various footwear. The reliability and validity were demonstrated by comparison with our previous system. From the evaluation of the newly developed system, we found four suggestions as the following; a) Footwear does not always reduce the pressure and shear force. b) Fixing the instep with shoelace or straps is effective in the reduction of shear force on risk regions of plantar. c) People with callus show significantly higher peak shear force (3.31 ± 0.78 (kgf)) than people without callus (2.03 ± 0.42 (kgf)) when they walk with their usual wearing shoes (p < 0.01). But in barefoot walking, there is no significant difference (2.59 ± 1.08 (kgf) versus 2.67 ± 0.99 (kgf), (p = 0.66)). d) People with callus can reduce the shear force by changing footwear. The system employed in this study can be used for assessing the effect of the intervention such as footwear or instruction of a walk.
Callosity; Diabetic foot; Gait analysis; Direct measurement; Therapeutic shoes
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Background
Gait has been widely and variously analyzed in clinical
settings [1]. For example, gait parameters such as walking
speed, cadence, step length and plantar pressure have been
measured for fall [2], diabetic foot [3], and osteoarthritis
[4]. Intervention by footwear is one of the major methods
for improving gait parameters for both prevention and
therapy. However, the evaluation of intervention by
footwear [5-7] is difficult, especially for diabetic patients
because they sometimes have neuropathy or foot
deformity [8,9]. Because their sensitivity for pressure and shear
force has decreased by neuropathy, it is hard to complain
to clinicians about the pain or abnormality on their
plantar. Also, even if patients have foot deformity, clinicians have
been estimating the effect of footwear only experientially.
Neuropathy, deformity and repetitive stress are known
key factors of foot ulcer [10]. Moreover, the forces known
to directly act on the foot are the plantar pressure (the
force that act in the vertical direction) and the shear force
(the shift force in the horizontal direction) [11]. If the
patient has foot deformities or callus, the application of high
pressure on the local regions would result in ulcer
formation through infection or injury [12]. It has been
particularly reported that patients with callus have very high risks
of developing foot ulceration. Furthermore, the plantar
pressure and the shear force are associated with callus
formation [13]. To prevent foot ulcer, both consultation
with experts and usage of footwear that reduce the force
load on local regions are recommended [14]. High
pressure is known to be exerted on the regions of the first and
second metatarsal heads during gait [15], and the regions
are frequent site of callus.
Owing to the lack of standard methods for the
objective clinical assessment of whether the footwear is
appropriate or not [6], callus formation has not been
effectively prevented. Hence in many cases, rather than
preventing it, therapeutic care is given, to remove the
callus after its formation. It is therefore important to
evaluate the effect of footwear on the risk plantar
regions by directly measuring the pressure and shear
force on the regions applied from footwear.
There are two major methods for measuring the force
applied on the foot during gait. One involves the use of
a force plate or sensors embedded in the ground
[16-18]. This method can only be applied in special
places, and the measured force is not the force on risk
regions of the plantar but the force that the footwear
applies on the ground. The other method involves the
use of specialized shoes or insoles with embedded
sensors [19,20]. In a study of Lord M et al., thin pressure
sensor sheets and special insoles with embedded
3.8mm-thick shear stress sensors we (...truncated)