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Technical Brief

Ability of a Novel Foot and Ankle Loading Device to Reproduce Loading Conditions in the Standing Position During Computed Tomography

[+] Author and Article Information
Tadashi Kimura

Department of Orthopaedic Surgery,
The Jikei University School of Medicine,
3-25-8 Nishi-Shinbashi,
Minato-ku, Tokyo 105-8471, Japan
e-mail: tadashi-kimura@jikei.ac.jp

Makoto Kubota

Department of Orthopaedic Surgery,
The Jikei University School of Medicine,
3-25-8 Nishi-Shinbashi,
Minato-ku, Tokyo 105-8471, Japan
e-mail: kubota_m@jikei.ac.jp

Tetsuya Taguchi

Department of Orthopaedic Surgery,
The Jikei University School of Medicine,
3-25-8 Nishi-Shinbashi,
Minato-ku, Tokyo 105-8471, Japan
e-mail: tetsuya3@tf6.so-net.ne.jp

Naoki Suzuki

Institute for High Dimensional Medical Imaging,
The Jikei University School of Medicine,
4-11-1 Izumihoncho,
Komae-shi, Tokyo 201-8601, Japan
e-mail: nsuzuki@jikei.ac.jp

Asaki Hattori

Institute for High Dimensional Medical Imaging,
The Jikei University School of Medicine,
4-11-1 Izumihoncho,
Komae-shi, Tokyo 201-8601, Japan
e-mail: hat@jikei.ac.jp

Keishi Marumo

Department of Orthopaedic Surgery,
The Jikei University School of Medicine,
3-25-8 Nishi-Shinbashi,
Minato-ku, Tokyo 105-8471, Japan
e-mail: hirakawa@jikei.ac.jp

1Corresponding author.

Manuscript received January 30, 2015; final manuscript received July 13, 2015; published online August 12, 2015. Assoc. Editor: Rita M. Patterson.

J. Med. Devices 9(4), 044506 (Aug 12, 2015) (4 pages) Paper No: MED-15-1020; doi: 10.1115/1.4031100 History: Received January 30, 2015

To describe a loading device, we created for use with current computed tomography (CT) scanners and to evaluate its ability to reproduce loading conditions. Ten feet of five healthy volunteers (three men and two women) with no history of foot or ankle disorders and no foot pain were studied. Subjects lay on the device in the supine position with the legs extended and ankles in a neutral position. An axial load equivalent to their body weight was applied to the soles. A foot scan measured plantar contact area, plantar pressure, and the center of pressure under standing and weight-bearing conditions. Differences between measurements were assessed using the paired t test with a two-sided significance of 5%. No subjects complained of pain or discomfort during loading. Weight-bearing measurements varied from standing measurements as follows: plantar contact area, −4.15 cm2; contact % (forefoot/midfoot/hindfoot), −0.61%/−0.17%/0.79%; plantar pressure, −1.47 N/cm2/−0.49 N/cm2/3.7 N/cm2 (6.40 N/cm2 overall); and center of pressure location (anterior–posterior/medial–lateral), 0.88%/0.36%. With the numbers available, no significant difference could be detected for any tested items. We were able to produce load distributions and intensities resembling standing conditions. Thus, the standing condition can be well produced on CT images if our device is used. Furthermore, images can be compared with those of healthy individuals to yield useful information for elucidating the pathophysiology and pathology of foot disorders.

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References

Figures

Grahic Jump Location
Fig. 1

Loading device used in this study. Three main parts: a foot plate, a backboard, and shoulder pads. Weight plates were hung from the hook attached to the rope for loading.

Grahic Jump Location
Fig. 2

Measurement method. (a) Standing condition measurements and (b) measurements taken with the loading device in use. (c) Representative footscan and method for calculating the center of pressure. Pressure is indicated by the color scale from red (high) to blue (low). The medial–lateral direction = a/b: the distance from the medial tangents of the hindfoot and forefoot to the center of pressure over the distance between the medial and lateral tangents. The anterior–posterior direction = c/d: the distance from the trailing edge of the heel to the center of pressure over the length of the foot.

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