Repeatability of the Pedar-X® in-shoe pressure measuring system

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Abstract

Background

The Pedar-X® is one of the newer versions of in-shoe pressure measuring devices and the current study aimed to assess the repeatability of this device.

Methods

Twenty-seven healthy male volunteers were recruited and requested to walk on a 26-feet walkway wearing appropriate sized standardised off-the-shelf neutral running shoes (Donnay® International). The Pedar-X® insole was sandwiched between the foot and the shoe. Data were collected on two occasions, one week apart. Clinically relevant parameters studied were contact area, contact time in percentage roll over process, maximum force, pressure–time integral, force–time integral, peak pressure, mean force and mean area.

Results

Repeatability was analysed using the coefficient of variation. Of the 160 parameters considered, 93.1% revealed a coefficient of variation value of less than 25. Heel and the metatarsal head areas were the most repeatable.

Conclusion

The Pedar-X® in-shoe pressure measuring system is repeatable and as such can be used as a valuable tool in the assessment of in-shoe plantar pressure distribution.

Introduction

The foot is one of the most complex biomechanical structures in the human body. As quoted by Leonardo da Vinci in the 15th century, “the human foot is a masterpiece of engineering and a work of art”. The normal foot functions in an extremely efficient manner in carrying the torso and off loading the body's weight to the ground while standing and walking. It also deals with the ground reaction forces (GRF) and takes up the cyclical load throughout the gait cycle as it is the only part of the normal human body that comes in contact with the ground during bipedal locomotion. It constantly adapts during walking, jogging, running and jumping demonstrating excellent maneuverability. A normal human walks approximately 3.5 million steps per year [1].

Various quantification equipment using different technologies are available for foot pressure analysis [2]. Many authors have previously used in-shoe pressure technology for evaluating the pressure distribution under the foot, which in turn is essential for accurate assessment of foot and gait pathologies [3], [4], [5], [6], [7]. The repeatability of earlier models of the Pedar® in-shoe system has been evaluated by Kernozek et al. [8] and Putti et al. [9].

Pedar-X® is a relatively new product among the in-shoe pressure measuring devices. As clinical decisions and treatment strategies are planned based upon data from these invaluable systems, no more emphasis is needed for utilising highly dependable equipment. Repeatability is one of the elements which may define such dependability. This study was designed to assess the repeatability of the Pedar-X® in-shoe pressure measurement system.

Section snippets

Materials and methods

After obtaining the University Research Ethics Committee's approval, the study was conducted by recruiting 27 healthy male volunteers. Participants with foot and ankle, knee, hip and spine pathologies, previous injuries and/or surgeries to the foot and ankle, limb length discrepancies and those with any clinical problems that could potentially affect their gait were excluded. On acquiring informed consent, anthropometric measurements including height, weight, shoe size and foot dimensions were

Results

Corresponding areas of both feet showed near similar repeatability for most of the parameters (Table 1, Table 2).

Discussion

Dynamic pedobarography is a constantly expanding field with new devices being designed and employed for various clinical applications. The repeatability of the earlier Pedar® in-shoe systems were evaluated [8], [9]. During the normal gait process, the heel initiates the ground contact of the foot and progressively the load is spread across the various areas of the foot, among which the metatarsal heads’ region is one of the most important. The Pedar-X® system showed a similar repeatability

Conclusion

This study concludes that the Pedar-X® system is repeatable. The studied parameters followed a pattern of almost identical repeatability in both feet. The system showed a motif of greater number of parameters with higher repeatability under the heel and the metatarsal head regions. The mid foot and hallux showed a moderate degree of repeatability. The accuracy of the system would improve if the repeatability under the comparatively less repeatable areas was also addressed.

Conflict of interest statement

The authors have no personal, professional or financial affiliations with other people or organisations that may be perceived to have biased the presentation.

Acknowledgements

The authors would like to thank Mr I. Christie for his technical assistance. The study was internally funded by the Institute of Motion Analysis & Research.

References (13)

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