Changes in sub-calcaneal fat pad composition and their association with dynamic plantar foot pressure in people with diabetic neuropathy

Abstract

Background: Diabetic foot disease is associated with physiological and biomechanical abnormalities in the foot that increase risk for ulceration. The objective was to assess MRI changes in the composition of sub-calcaneal fat pad tissue and its association with plantar pressure during walking. Methods: Fourteen people with diabetes and peripheral neuropathy and five age-matched healthy controls underwent T1-weighted sagittal plane spin-echo Dixon MRI of the rearfoot. Dixon Chemical Shift Imaging was used to create fat-only and water-only images from which the fat signal fraction in a defined ROI of the sub-calcaneal fat pad was calculated. Barefoot plantar pressure distribution during walking was assessed and associated with fat pad outcomes. Findings: Mean ± SD fat signal fraction was significantly lower in the neuropathic subjects than in the healthy controls (0.55 ± 0.11 vs. 0.72 ± 0.03, p < 0.005), and was explained by a lowering in fat signal (R 2 0.87), more than an increase in water signal (R 2 0.32). Mean ± SD peak pressure at the heel was 391 ± 119 kPa for the neuropathic subjects and 325 ± 53 kPa for the healthy controls (non-significantly different). Fat signal fraction and peak pressure were significantly inversely correlated (r = − 0.59, p < 0.01). Interpretation: Dixon chemical shift MRI showed a reduced fat signal fraction in sub-calcaneal fat pad tissue in people with diabetic neuropathy. Both neuropathic and non-neuropathic factors may be attributed to this outcome. Fat pad function also seems to be compromised, as indicated by an associated increase in peak plantar pressures. This may increase risk for foot ulceration.

Advancements in diabetic foot insoles: a comprehensive review of design, manufacturing, and performance evaluation

“…The development of diabetic foot is not solely linked to neuropathy and changes in blood glucose but is also influenced by biomechanics ( Asghar and Naaz, 2022 ). The plantar pressure distribution in healthy individuals versus diabetic foot patients differs significantly, as depicted in Figure 3A ( Deschamps et al, 2013 ; Fernando et al, 2016 ; Bus et al, 2021 ). Moreover, variations exist in pressure conditions across different plantar areas, as illustrated in Figure 3B ( Perren et al, 2021 ).…”

Comparison of material properties of heel pad between adults with and without type 2 diabetes history: An in-vivo investigation during gait

“…The biomechanical changes in DM patients have been widely investigated with various methods (9,28,35,(40)(41)(42)(43)(44)(45)(46). However, it remains a difficulty to accurately measure the material properties of heel pad during normal gait with noninvasive approach.…”

“…Thus, if the tissue losses the viscoelasticity due to the continuous accumulation of the AGEs, its capacity of absorbing the shock and uniformly distributing loads during weight bearing activity will be reduced (36). In the previous studies, stiffness has always been the mostly concerned material property of heel pad, and most of them demonstrated increased stiffness for plantar tissue of diabetes patients (9,28,35,(40)(41)(42)(43)(44)(45)(46). However, in our results, we detected minor decrease of stiffness in diabetes patients compared with that of healthy subjects at time zero, and similar stiffness was found following continuous loading.…”

“…It is estimated that 10% and 19% of the DFU patients would encounter major amputation and minor amputation respectively, within 1 year of diagnosis ( 7 ). Although the heel ulcerations are less common than forefoot ulcerations, they are generally more challenging to treat, difficult to heal and associated with larger morbidity and higher costs ( 8 , 9 ). It is reported that the limb salvage success rate of heel ulcers is 2~3 times less than that of the forefoot ulcers ( 8 ).…”

Effects of heel apex position, apex angle and rocker radius on plantar pressure in the heel region

“…Ulcers in the heel occur less frequently than the ones in the forefoot, however they are more difficult and 1.5 times more expensive to treat [ 4 ]. Repetitive stress on the heel, in combination with loss of protective sensation (LOPS) due to peripheral neuropathy and loss of fat pad quality due to DM, leads to unnoticed skin breakdown that often results in DFUs [ [5] , [6] , [7] ].…”