Monitoring skin temperature through orthopedic casts with infrared thermography: a feasibility study

While essential for immobilization and healing following various surgeries, orthopedic casts can contribute to the breakdown of skin integrity due to prolonged pressure, leading to the development of pressure injuries (PIs). Monitoring sub-cast skin integrity allows for early identification and prevention of PIs, reducing the risks of further complications and related healthcare costs. Since temperature is an important indicator of skin integrity, we investigated the correlation between cast-surface and sub-cast temperatures using infrared thermography. Benchtop experiments were carried out using 3D-printed phantoms that simulated skin conditions at different stages of PI, including wound size and exudate. Orthopedic casts of various compositions were applied over the phantoms, which were infrared heated to typical cutaneous temperatures. Thermal images were acquired of the cast surfaces and the corresponding regions of the phantoms sub-cast. Regression analysis revealed that cast-surface temperatures were positively correlated with sub-cast temperatures. The correlation between cast-surface and sub-cast temperatures decreased with additional casting layers. Comparing different casting materials, thermal images of fiberglass cast surfaces retained higher signal-to-noise ratios than those of plaster casts, suggesting more efficient heat transfer. These findings indicate the potential of deriving skin temperature information through casts. Further investigations to determine the spatial and thermal sensitivity of infrared thermography to localized sub-cast skin temperature changes are warranted.