October 2012

Midfoot index of load differentiates postarthrodesis gait from normal

In the moment: Surgery

By Jordana Bieze Foster

Swiss researchers have found that pedobarographic differentiation between ankle arthrodesis patients and healthy volunteers can be narrowed down to a single variable, midfoot index of load—a finding that could make the technology much more accessible to the average clinician.

Investigators from University Hospital Basel in Basel, Switzerland, analyzed dynamic pressures in 35 healthy volunteers and 99 patients who had undergone arthrodesis (57 ankle, 42 tibiotalocalcaneal) at least two years earlier. Midfoot index of load, which increased with more extensive fusion, was the most important predictor of abnormal gait. Midfoot load was also easily identifiable on force-time graphs: Healthy volunteers demonstrated a noticeable midfoot depression that was less prominent in the arthrodesis patients. The findings were e-published in September by Clinical Biomechanics.

“The midfoot depression in the foot is like the discovery of ST elevation or depression in ECG: every person can see infarction or ischemia, and with pedobarography every person can identify a limp or normal walking,” said Arno Frigg, MD, a consultant in the Department of Orthopaedic Surgery at University Hospital Basel.


Frigg A, Schafer J, Dougall H, et al. The midfoot load shows impaired function after ankle arthrodesis. Clin Biomech 2012 Sep 10. [Epub ahead of print]

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