Site-Specific, Critical Threshold Barefoot Peak Plantar Pressure Associated with Diabetic Foot Ulcer History: A Novel Approach to Determine DFU Risk in the Clinical Setting.

Barefoot peak plantar pressures (PPPs) are elevated in diabetes patients with neuropathic foot ulcer (DFU) history; however, there is limited reported evidence for a causative link between high barefoot PPP and DFU risk. We aimed to determine, using a simple mat-based methodology, the site-specific, barefoot PPP critical threshold that will identify a plantar site with a previous DFU. In a cross-sectional study, barefoot, site-specific PPPs were measured with normal gait for patients with DFU history ( = 21) and healthy controls ( = 12), using a validated carbon footprint system. For each participant, PPP was recorded at twelve distinct plantar sites (1st-5th toes, 1st-5th metatarsal heads (MTHs), midfoot and heel), per right and left foot, resulting in the analysis of = 504 distinct plantar sites in the diabetes group, and = 288 sites in the control group. Receiver operator characteristic curve analysis determined the optimal critical threshold for sites with DFU history. Median PPPs for the groups were: diabetes sites with DFU history ( = 32) = 5.0 (3.25-7.5) kg/cm, diabetes sites without DFU history ( = 472) = 3.25 (2.0-5.0) kg/cm, control sites ( = 288) = 2.0 (2.0-3.25) kg/cm; ( < 0.0001). Diabetes sites with elevated PPP (>6 kg/cm) were six times more likely to have had DFU than diabetes sites with PPP ≤ 6 kg/cm (OR = 6.4 (2.8-14.6, 95% CI), < 0.0001). PPP > 4.1 kg/cm was determined as the optimal critical threshold for identifying DFU at a specific plantar site, with sensitivity/specificity = 100%/79% at midfoot; 80%/65% at 5th metatarsal head; 73%/62% at combined midfoot/metatarsal head areas. We have demonstrated, for the first time, a strong, site-specific relationship between elevated barefoot PPP and previous DFU. We have determined a critical, highly-sensitive, barefoot PPP threshold value of >4.1 kg/cm, which may be easily used to identify sites of previous DFU occurrence and, therefore, increased risk of re-ulceration. This site-specific approach may have implications for how high PPPs should be investigated in future trials.