Comparison of pressure and time parameters in evaluating diabetic footwear

Objective: Although peak pressure has been used in the evaluation of diabetic footwear, other potential parameters have remained unstudied. This study was undertaken to compare the effects of diabetic footwear on pressure-time integral, peak pressure, and contact time in different areas of the foot. Design: In-shoe pressure was measured and analyzed separately in the left and right feet of 14 diabetic patients with neuropathy by using 24 discrete sensors for each foot; pressure-time integral, peak pressure, and contact time at 48 data points were compared between patients wearing their own shoes and patients wearing diabetic footwear. Results: The three parameters were symmetrically reduced in the anterior and posterior parts of bilateral feet and increased in the middle part of bilateral feet. The 34 sensors that showed significant changes in pressure-time integral included all 23 sensors that showed significant changes in peak pressure, and 15 of 18 sensors showed significant changes in contact time. The change of the pressure-time integral was correlated to walking speed at 17 sensors, sex at five, body mass index at four, and speed difference at two. Conclusions: The effect of diabetic footwear is detected at more sensors by pressure-time integral than by peak pressure and contact time. The slower a patient walks, the greater the change of the pressure-time integral by diabetic footwear. It is suggested that pressure-time integral be routinely included in the evaluation of diabetic footwear for each patient.