The mechanism of plantar unloading in total contact casts

Implications for design and clinical use

Jonathan E. Shaw, Wei Li Hsi, Jan Ulbrecht, Arleen Norkitis, Mary B. Becker, Peter R. Cavanagh

Research output: Contribution to journalArticle

93 Citations (Scopus)

Abstract

Although the total contact cast (TCC) has been shown to be an extremely effective treatment for the healing of plantar ulcers in diabetic patients, little is known about the biomechanics of its action. In this study, plantar pressure and ground reaction force measurements were obtained from over 750 foot contacts as five subjects with known elevated plantar forefoot pressures walked barefoot, in a padded cast shoe, and a TCC. Peak plantar pressures in the forefoot were markedly reduced in the cast compared with both barefoot and shoe walking (reductions of 75% and 86% respectively, P < 0.05). Peak plantar pressures in the heel were not, however, significantly different between the shoe and the TCC, and the longer duration of heel loading resulted in an impulse that was more than twice as great in the cast compared with the shoe (P < 0.05). An analysis of load distribution indicated that the mechanisms by which the TCC achieves forefoot unloading are (1) transfer of approximately 30% of the load from the leg directly to the cast wall, (2) greater proportionate load sharing by the heel, and (3) removal of a load- bearing surface from the metatarsal heeds because of the 'cavity' created by the soft foam covering the forefoot. These results point out some of the 'essential design features' of the TCC (which are different from what had been previously supposed), support the use of the TCC for healing plantar ulcers in the forefoot, but raise questions about its utility in the healing of plantar ulcers on the heel.

Original languageEnglish (US)
Pages (from-to)809-817
Number of pages9
JournalFoot and Ankle International
Volume18
Issue number12
DOIs
StatePublished - Jan 1 1997

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Shoes
Heel
Foot Ulcer
Pressure
Metatarsal Bones
Weight-Bearing
Biomechanical Phenomena
Walking
Leg
Therapeutics

All Science Journal Classification (ASJC) codes

  • Surgery
  • Orthopedics and Sports Medicine

Cite this

Shaw, J. E., Hsi, W. L., Ulbrecht, J., Norkitis, A., Becker, M. B., & Cavanagh, P. R. (1997). The mechanism of plantar unloading in total contact casts: Implications for design and clinical use. Foot and Ankle International, 18(12), 809-817. https://doi.org/10.1177/107110079701801210
Shaw, Jonathan E. ; Hsi, Wei Li ; Ulbrecht, Jan ; Norkitis, Arleen ; Becker, Mary B. ; Cavanagh, Peter R. / The mechanism of plantar unloading in total contact casts : Implications for design and clinical use. In: Foot and Ankle International. 1997 ; Vol. 18, No. 12. pp. 809-817.
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Shaw, JE, Hsi, WL, Ulbrecht, J, Norkitis, A, Becker, MB & Cavanagh, PR 1997, 'The mechanism of plantar unloading in total contact casts: Implications for design and clinical use', Foot and Ankle International, vol. 18, no. 12, pp. 809-817. https://doi.org/10.1177/107110079701801210

The mechanism of plantar unloading in total contact casts : Implications for design and clinical use. / Shaw, Jonathan E.; Hsi, Wei Li; Ulbrecht, Jan; Norkitis, Arleen; Becker, Mary B.; Cavanagh, Peter R.

In: Foot and Ankle International, Vol. 18, No. 12, 01.01.1997, p. 809-817.

Research output: Contribution to journalArticle

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