Diabetic foot screening must see: three indicators of early warning ulcer risk in plantar scanners

[Diabetic foot ulcer early warning revolution: decoding of three core indicators of plantar scanner]

——Clinical breakthrough based on multispectral imaging and biomechanical modeling

1. Temperature variation gradient (TDG)

6-8 months before the occurrence of diabetic foot ulcer, local microcirculation disorders in the affected foot cause characteristic temperature abnormalities. The third-generation plantar scanner achieves accurate capture through the following technologies:

Infrared thermal imaging system‌

Equipped with a 640×480 resolution thermal sensor, it can identify a temperature difference of 0.03℃ and accurately locate high-risk areas such as the arch and forefoot. Clinical data show that in areas with a plantar temperature difference of ≥2.1℃, the risk of ulcers increases by 4.7 times within 6 months‌.

Day and night fluctuation monitoring‌

Dynamically record the 24-hour foot temperature change curve. The day and night temperature difference of a healthy foot is ≤1.2℃, while the fluctuation in the microcirculation disorder area can reach 3.5-4.8℃. Abnormal fluctuations lasting for 3 weeks will trigger a secondary warning‌

Treatment response evaluation ‌

After drug treatment, the target area temperature standard deviation (TSD) dropped to within 0.8℃, indicating that vascular reconstruction was effective and the risk of ulcers was reduced by 62%‌.

2. Skin Lesion Index (SLI)

The high-resolution imaging system (12 million pixels) combined with the AI algorithm can quantitatively evaluate early skin damage:

Water content of the stratum corneum ‌

Microwave resonance technology is used to detect the water gradient from the epidermis to the dermis (0.3-2mm depth). In areas with water content below 45%, the epidermal barrier function decreases and the risk of microbial colonization increases by 3 times‌.

Subcutaneous blood oxygen saturation ‌

Multispectral imaging (450-950nm) detects HbO2 concentration. When the blood oxygen value on the outside of the arch is <82%, the tissue repair ability decreases to the dangerous threshold‌.

Microstructure analysis‌

40x optical magnification identifies subclinical injuries such as stratum corneum fissures (＞30μm) and abnormal sweat pore density (＜2/mm²), and detects lesion trends 9 months earlier than naked eye observation‌.

III. Gait feature matrix (GFM)

Biomechanical early warning model established based on motion capture system (200Hz sampling rate):

Heel lift-off angle‌

The heel lift-off angle of patients with diabetic neuropathy is reduced by 8-12°, resulting in a 2.3-fold increase in the friction coefficient of the forefoot. Continuous deviation from the normal value (18-22°) indicates abnormal plantar shear force‌.

Support phase time ratio‌

The single-step support phase ratio of the affected foot is ＞62% (healthy value 55±3%), indicating that the foot load-bearing compensation mechanism is activated and the risk of local pressure accumulation is increased‌.

Three-dimensional gait symmetry‌

The gait deviation angle (GDA) is calculated by fitting the hip-knee-ankle joint motion trajectory. When GDA>7.5° and lasts for 3 months, the incidence of foot ulcers increases to 41%.

This technical system advances the warning window for diabetic foot ulcers to 9-12 months, with a positive predictive value of 89.3% (52.1% for traditional methods). However, it should be noted that patients under 18 years old need to exclude epiphyseal development interference, and people over 70 years old should verify microcirculation data in combination with angiography.