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Could Seamed Socks Impart Unduly High Pressure to the Diabetic Foot?
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Could Seamed Socks Impart Unduly High Pressure to the Diabetic Foot?
By Susan Stacpoole-Shea B.App.Sc.(Pod), Gail Walden BS MPH,
Elizabeth Villarreal, David Armstrong DPM, & Lawrence Lavery DPM MPH
Dept. of Orthopaedics,
University of Texas Health Science Center at San Antonio, Texas
School of Human Movement & Sport Sciences,
University of Ballarat Victoria Australia
Audie Murphy Veterans Administration Hospital, San Antonio, Texas
Introduction
Irritation from footwear is one of the most readily preventable factors leading to ulceration in the high-risk diabetic foot.
The role of socks has received substantially less attention than shoes and insoles in the care of this population, both in their role to prevent or cause foot ulceration.
Anecdotally, the irritation associated with a sock seam being trapped between the foot and shoe has been the culprit in many foot ulcerations.
It is hypothesized that an increase in pressures of >40% in a bench test could suggest that a sock seam trapped between the foot and shoe could be expected to be of sufficient magnitude to be the culprit in compromising the diabetic and neuropathic foot and lead to ulceration.
Purposes of study
To determine, in the laboratory, if a sock seam could form a localized focus of high pressure.
To assess the suitability of the F-scan (Tekscan Boston, MA) Pressure Analysis System to identify the location of the sock seam and allow for pressure measurement.
Methods
A bench-based test was designed to address both purposes of study.
Socks
Two department store socks with sewn seams (seamed socks) (Fruit of the Loom, Mt. Airy, NC) were selected and compared against a sock with a knitted seam (seamless sock) (Knit-Rite Inc. Kansas City, KS).
Instrumentation
The F-scan In-sole Pressure Analysis System 4.11 was selected for the study due to its high sensor resolution. A new sensor was utilized for each sock tested based on the assumption that each sensor is factory equilibrated. The system was calibrated and all software procedures were conducted as described in the F-scan 4.11 Users Manual.
Procedure
The plantar surface of the sock was removed.
The sensor and the sock sample were "sandwiched" between two flat and unyielding surfaces.
A 65Kg (adult body) weight applied force to the apparatus.
Sensor data was captured from 5 trials each sock by the F-scan 4.11 software and imaged on the computer monitor.
Data Analysis
The seam area and a non-seam area of each sock sample were identified by the investigator to create an "object" file for analysis.
Data was analyzed by the F-scan 4.11 software from 3 points from the 8s of data collected for each trial and exported into Microsoft Excel 97 for presentation.
Results
Conclusion
This bench-based study lends preliminary evidence to support the anecdotal clinical evidence that a sock seam can lead to a focus of high pressure. The level of pressure (10 fold) measured at the seam is much greater than that which is reported to correspond with known peak pressures on the foot in persons with neuropathy and diabetes. Consequentially, the clinician may be well advised to consider including the wearing of seamless socks into their patient's "diabetes foot risk management plan" if these data are validated in human subjects. Additionally, sock manufacturers could be encouraged to continue the production of "seamless" socks.
Acknowledgements
Graeme Shea MCSE Grad. Dip. Computing and Dr's Toni Miles MD PhD and Norman Murphy PhD for their advise and support in the planning of this protocol.
Financial support for this study was provided by:
University of Ballarat, School of Human Movement and Sport Sciences, Victoria, Australia and John A. Hartford Center of Excellence in Geriatric Education University of Texas Health Science Center at San Antonio, Texas USA.
This study is submitted in partial fulfillment towards Susan Stacpoole-Shea's PhD thesis.
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