Peer-Reviewed, Published Research

In 1989 the first research using sock products was published. In it, the benefits of padded, engineered sock products for reducing pressure in the insensitive diabetic foot were documented. This research was followed by seven other key studies that confirmed the benefits of padded, engineered sock products for preventing blisters, reducing pressure and pain, and enhancing circulation. These studies are summarized below.

Today, IPFH continues to fund and sponsor research that enables us to learn more about the feet and footwear for both preventive and therapeutic purposes.

• "Use of Experimental Padded Hosiery to Reduce Abnormal Foot Pressures in Diabetic Neuropathy"
  
  Aristidis Veves, MD; Ewan Masson, MRCP; Devaka Fernando, MRCP; Andrew J.M. Boulton, MD (published in Diabetes Care, vol. 12, No. 9. October, 1989).

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  Twenty-seven patients (fifteen men and twelve women) with diabetes and abnormal plantar pressures, ranging in age from 26 to 78 years, took part in the study. The objective was to define effective strategies to protect the high-risk diabetic foot from ulceration and amputation.

  In the study population, the results were:

  • Pressure and shearing force were identified as key factors in the development of foot ulcers.
  • A significant reduction in both peak pressure and pressure over time was shown in the population wearing the ThorlosÒ sock product, fitted properly with shoes.
  • A significant reduction in dynamic foot pressure was demonstrated in participants from wearing the Thorlos sock product. Conclusion: Thorlos sock products are a useful, acceptable, relatively inexpensive method for protecting the insensitive foot from abnormal pressures (which are the causes of most foot pathologies).

• "Studies of Experimental Hosiery in Diabetic Neuropathic Patients with High Foot Pressures"
  
  Aristidis Veves, MD; Ewan Masson, MRCP; Devaka Fernando, MRCP; Andrew J.M. Boulton, MD. Published in Diabetic Medicine, vol. 7, pgs 324-326. January, 1990.

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  Four patients with Type 1 diabetes, and six patients with Type 2 diabetes (both groups had diminished sensation in their feet) participated in a longitudinal test of experimental sock products made by THOR·LO. Six of the patients had histories of prior ulceration. Diaries of sock wear were kept by participants, and dynamic pressure measurements using a pedobarograph were taken at inception, and at three months and six months after inception.

  In the study population, the results were:

  • Pressure stress on diabetic neuropathic feet was reduced: Thorlo sock products reduced peak foot pressures by 31% at base line.
  • After 6 months of use, the products still reduced peak foot pressure by 17%. Conclusion: The combination of Thorlos sock products and "sensible" depth shoes may be of great value at a very low cost in the care of the diabetic foot.

• "Friction Blisters and Sock Fiber Composition, a Double Blind Study"
  
  Kirk M. Herring, DPM and Douglas H. Richie, Jr., DPM; published in the Journal of the American Podiatric Medical Association, Vol. 80 no. 2, February, 1990. [This study was a comparison of two sock products, both done in the patented Thorlos design for runners - one in an acrylic yarn construction and the other in a cotton yarn construction. It was followed by Part 2 (as described below)].

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  Thirty-five long distance runners (twenty-one male and fourteen female) completed 80 run trials wearing Specific Thorlos patented sock products made from 100% acrylic fibers. Runners also completed 80 run trials wearing Specific Thorlos patented sock product made from 100% natural cotton fibers. Average run duration was 6.5 miles, an average of 5 to 6 times per week. In the study population the results were:

  • The Thorlos sock product construction with acrylic fiber kept feet drier than the Thorlos sock product construction with cotton fiber.
  • Participants testing the Thorlos sock product construction with acrylic fiber showed 50% fewer blisters than they did with the Thorlos sock product construction with cotton fiber.
  • When blisters did occur, the Thorlos sock product construction with acrylic fiber showed blisters that were only one-third the size of those resulting from the Thorlos sock product construction with cotton fiber.

  Conclusion: The Thorlos acrylic fiber sock products were associated with fewer blistering events and smaller blisters (as measured in mm2) when compared directly to the Thorlos cotton fiber sock products.

• "Friction Blisters and Sock Fiber Composition, a Single Blind Study (Part 2)"
  
  Authors: Kirk M. Herring, DPM, Douglas H. Richie, Jr, DPM. Presented at 75th Annual Meeting of the American Podiatric Medical Association, Las Vegas, NV, August, 1990. Also published in the Journal of the American Podiatric Medical Association, Volume 83 number 9 entitled "Comparison of Cotton and Acrylic Socks Using a Generic Cushion Sole Design for Runners," September, 1993.

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  Twenty-seven runners (eighteen males and nine females) completed 20 runs of 45 minutes each to compare two generically constructed socks. One sock was constructed with acrylic fibers and the other with cotton. These ordinary socks were constructed without the dense padding found in the patented Specific Thorlos design. Average run duration was between 6 and 7 miles, an average of 6 days per week. In the study population the results were:

  • No significant difference in blister frequency was noted in the generic acrylic cushioned construction as compared with the generic cotton cushioned construction.
  • No significant difference in size or severity of blisters was noted in the generic acrylic construction as compared with the generic cotton construction.

  Conclusion: Part 1 of this research (Herring and Richie, 1990) demonstrated that there was significant blister reduction in the Thorlos padded construction with acrylic fiber (versus the Thorlos patented construction with cotton fiber). This might have been interpreted simply as the fact that acrylic is a more effective fiber than cotton in reducing blisters. In order to test this hypothesis, Herring and Richie conducted part 2. The result of this part 2 test was that ordinary socks with a generic cushion construction showed no significant difference in blistering between the acrylic and the cotton constructions. Therefore, the conclusion from the results of the combined studies is that the reduction in blister size and frequency was attributable to a combination of the acrylic yarn construction, together with the patented padded Thorlos sock product design.

• "The Use of Specially Padded Hosiery in the Painful Rheumatoid Foot"
  
  A. Veves, E.M. Hay, A.J.M. Boulton; University Departments of Medicine and Rheumatology, Manchester Royal Infirmary, Manchester, UK, 1992. Published in The Foot, International Journal of Clinical Foot Science Vol. 1, 1992.

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  Eighteen patients (seven males, eleven females) with rheumatoid arthritis and painful feet, ranging in age from 30 to 71 and with an average duration of nearly twelve years of duration of the disease, participated in a six-month study. Participants wore one type of Thorlos sock products for three months and then switched to the other type for the remaining three-month period. Each group wore both an experimental heavy density padded sock product, and a commercially available Thorlos sock product (Walking Thorlos). In the study population, the results were:

  • Significant pressure relief was experienced during walking and standing with the experimental sock product.
  • Painful symptoms were reduced 51% while wearing the experimental Thorlos hosiery during walking and standing (as measured on a subjective pain reporting test).
  • Painful symptoms were reduced 45% while wearing the walking Thorlos hosiery during walking and standing (as measured on a subjective pain reporting test).
  • Both products performed satisfactorily over a long period of regular use.

  Conclusion: Thorlos sock products are useful in providing pressure and pain relief in the painful rheumatoid foot.

• "Role of Experimental Socks in the Care of the High Risk Diabetic Foot"
  
  A multi-center patient evaluation study. Heather J. Murray, DPOD M, Aristidis Veves, M.D.; Matthew J. Young, M.D.; Douglas H. Richie, DPM; A.J.M. Boulton, MD. American Group for the Study of Experimental Hosiery in the Diabetic Foot. Published in Diabetes Care, Vol. 16, Number 8; August, 1993.

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  Eighty-six high-risk patients (sixty-nine males, 14 with Type 1 diabetes, and seventeen females), ranging in age from 34 to 85 years old participated. The participants were provided with three pairs of specially padded Thorlos and extra depth shoes. Feet were examined 3 months and 6 months after the beginning of the study.

  In the study population the results were:

  • Thorlos sock products provided more comfort according to patients' subjective responses.
  • Patient satisfaction as evaluated was good or very good in 85% of participants.
  • Patient compliance was high, with 84% of participants indicating that they wore the sock products all or most of the time due to the comfort they provided.

  Conclusion: Thorlos sock products provide a high level of patient satisfaction and a high rate of patient compliance, and are an acceptable, relatively inexpensive method of protecting the high risk insensitive diabetic foot.

• "Nonprescription, padded, lightweight support socks in treatment of mild to moderate lower extremity venous insufficiency"
  
  Authors: Dr. Alice Brown, Pharm D.; Dr. Jack Brown, D.O. Published in the Journal of the American Osteopathic Association - March, 1995.

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  Thirty-six men with mild to moderate venous insufficiency (as measured using Doppler ultrasound techniques), ranging in age from 27 to 83 years, participated in this modified single-crossover study. Participants wore Specific Thorlos for three months - half the group wore crew length Thorlos and the other half wore over-calf support Thorlos. After one month, those in the group wearing the crew length Thorlos were switched to over-calf support Thorlos if in the initial assessment they were in the lower 50th percentile in venous insufficiency.

  In the study population the results were:

  • Improved circulation in feet and in legs as measured by deep venous valve function and venous capacity was experienced in all of those wearing Thorlos sock products with properly fitted shoes.
  • During the three months, the number and severity of vascular complaints decreased dramatically.

  Conclusion: People with the feeling of chronic aching and fatigue in their feet and legs will actually improve with Thorlos sock products. Nonprescription, padded hosiery is a simple and effective mode of treatment, and should be considered as first line of therapy for mild to moderate venous insufficiency. [The conclusion also supports the idea that Thorlos sock products, used in a systems approach, will produce therapeutic and preventive benefits for other foot issues where circulation is a critical factor]

• "The Effect of Padded Hosiery in Reducing Forefoot Plantar Pressures"
  
  Authors: Shawn Flot, MPT; Von Hill, MPT; Wesley Yamada, DPM; Thomas McPoil, PhD, PT, ATC; Mark Cornwall, PHD, PT. Published in The Lower Extremity Vol. 2, No. 3; September, 1995.

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  Eight participants in good health (five males and three females), ranging in age from 23 to 44 years, tested a standard extra-depth shoe with a Specific Thorlos padded sock product for eight weeks against a non-padded control sock made from 100% cotton. Using a commercially available measuring device, in-shoe pressure measurements were taken each day during the study (the first time pressure sensors had been used inside the shoe in the testing of padded hosiery).

  In the study population the results were:

  • Padded hosiery significantly decreased forefoot plantar pressures at the sock / shoe interface, specifically in the hallux and the central forefoot regions of the foot.
  • Washing did not affect the performance of the padded hosiery in providing pressure reduction.

  Conclusion: Padded hosiery can significantly decrease forefoot plantar pressures when initially donned, after wearing for 4 hours of activity, and over a period of 8 weeks of wear.