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Open Access Methodology

A novel approach to mapping load transfer from the plantar surface of the foot to the walls of the total contact cast: a proof of concept study

Lindy Begg12*, Patrick McLaughlin34, Leon Manning1, Mauro Vicaretti12, John Fletcher12 and Joshua Burns125

Author Affiliations

1 Foot Wound Clinic, Department of Surgery, Westmead Hospital, PO Box 533, Wentworthville, NSW, 2145, Australia

2 Univeristy of Sydney, Department of Surgery, Westmead Hospital, PO Box 533, Wentworthville, NSW, 2145, Australia

3 School of Biomedical and Health Sciences, Faculty of Health, Engineering and Science, Victoria University, Melbourne, 8001, Australia

4 Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, VIC, 8001, Australia

5 Institute for Neuroscience and Muscle Research, The Children’s Hospital at Westmead/Paediatric Gait Analysis Service of New South Wales/Faculty of Health Sciences, The University of Sydney, Sydney, NSW, 2145, Australia

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Journal of Foot and Ankle Research 2012, 5:32  doi:10.1186/1757-1146-5-32

Published: 13 December 2012

Abstract

Background

Total contact casting is regarded as the gold standard treatment for plantar foot ulcers. Load transfer from the plantar surface of the foot to the walls of the total contact cast has previously been assessed indirectly. The aim of this proof of concept study was to determine the feasibility of a new method to directly measure the load between the cast wall and the lower leg interface using capacitance sensors.

Methods

Plantar load was measured with pedar® sensor insoles and cast wall load with pliance® sensor strips as participants (n=2) walked along a 9 m walkway at 0.4±0.04 m/sec. The relative force (%) on the cast wall was calculated by dividing the mean cast wall force (N) per step by the mean plantar force (N) per step in the shoe-cast condition.

Results

The combined average measured load per step upon the walls of the TCC equated to 23-34% of the average plantar load on the opposite foot. The highest areas of load on the lower leg were located at the posterior margin of the lateral malleolus and at the anterior ankle/extensor retinaculum.

Conclusions

These direct measurements of cast wall load are similar to previous indirect assessment of load transfer (30-36%) to the cast walls. This new methodology may provide a more comprehensive understanding of the mechanism of load transfer from the plantar surface of the foot to the cast walls of the total contact cast.

Keywords:
Total contact cast; Offloading; Plantar pressure; Diabetes