Welcome to the another Diabetes Digest. The paper I have chosen to comment upon is by Qin et al from Japan. This study sets out to examine the relationship between plantar callus and local increased skin temperature. These are both reported to be precursors for neuropathic foot ulceration, but the inter-relationship between these has not been explored in the literature. This was a cross-sectional retrospective study involving data from 1,007 patients who attended a diabetic foot prevention clinic between 2008 and 2020. Subject data for demographics, neuropathy, PAD, deformity, dry skin, footwear, static foot pressures, foot calluses and callus thermographic hotspots were collected and analysed. Calluses were determined from clinical photographs and callus hotspots were confirmed from foot thermographs taken after 15+ minutes non-weightbearing rest. A callus hotspot was defined as a relative increase in temperature compared to the skin surrounding on the thermograph. Plantar pressures were measured using the FScan™ pressure sensor system.
Subjects with active ulceration were excluded. Neuropathy was determined by a 10-g monofilament, vibration at the ankle, Achilles’ tendon reflex and a coefficient of variation R-R interval (CVRR) <0.2. An ill-fitting shoe was defined as the internal shoe length 1–2 cm than the foot. Static barefoot peak pressures (SFPPP) were taken pre-callus removal. Callus-related variables were attributed as dry skin, foot deformity, ill-fitting shoes and static forefoot peak plantar pressure (SFPPP). Callus hotspot variables were ascribed as the number of calluses, location and whether or not they matched peak plantar pressure sites.
From the 2,014 feet, callus was present in 28.5% (n=574) with callus hotspots occurring in 106 (18.5%) of feet. The most frequent callus sites were the second MTH (23.6%), first toe (21.6%) and fifth MTH (19.9%). A linear mixed model showed the factors associated presence of calluses were female sex (OR: 1.749, P<.001), higher SFPPP (OR: 1.008, P<.001), foot deformity (OR: 3.003, P<.001) and dry skin (OR: 1.513, P=.007). The factors associated with hotspots on calluses were BMI (OR: 0.912s P=.029), SFPPP (OR: 1.008, P=.001) and the number of calluses (OR: 1.540, P=.003). Interestingly, they were not significantly associated with neuropathy, deformity, poor footwear or dry skin.
There are several noticeable limitations to this study. Firstly, it was a cross-sectional retrospective study using data over 12 years with possible inconsistent data. There was no reported data regarding daily activity levels, frequency of footcare and self-care. Additionally, multiple consecutive thermographic and SFPPP measurements were not performed to assess for inflammation. Due to the study design, the causal relationship between factors and outcomes could not be postulated and due to subjects resting for at least 15 minutes before thermography, it would be intriguing and potentially more valid to examine for callus hotspots immediately after exercise and the time taken for these to return to resting values.
Despite these limitations, it is an interesting study which raises some interesting questions from clinical, research and educational perspectives, thus, it would be a good read for those seeking professional development. It also underlines the importance of identifying those who are at most risk of ulceration and provides markers for prevention.
The Diabetic
Foot Journal
Issue:
Vol:24 | No:02
Digest: Know your local hotspots!
Subjects with active ulceration were excluded. Neuropathy was determined by a 10-g monofilament, vibration at the ankle, Achilles’ tendon reflex and a coefficient of variation R-R interval (CVRR) <0.2. An ill-fitting shoe was defined as the internal shoe length 1–2 cm than the foot. Static barefoot peak pressures (SFPPP) were taken pre-callus removal. Callus-related variables were attributed as dry skin, foot deformity, ill-fitting shoes and static forefoot peak plantar pressure (SFPPP). Callus hotspot variables were ascribed as the number of calluses, location and whether or not they matched peak plantar pressure sites.
From the 2,014 feet, callus was present in 28.5% (n=574) with callus hotspots occurring in 106 (18.5%) of feet. The most frequent callus sites were the second MTH (23.6%), first toe (21.6%) and fifth MTH (19.9%). A linear mixed model showed the factors associated presence of calluses were female sex (OR: 1.749, P<.001), higher SFPPP (OR: 1.008, P<.001), foot deformity (OR: 3.003, P<.001) and dry skin (OR: 1.513, P=.007). The factors associated with hotspots on calluses were BMI (OR: 0.912s P=.029), SFPPP (OR: 1.008, P=.001) and the number of calluses (OR: 1.540, P=.003). Interestingly, they were not significantly associated with neuropathy, deformity, poor footwear or dry skin.
There are several noticeable limitations to this study. Firstly, it was a cross-sectional retrospective study using data over 12 years with possible inconsistent data. There was no reported data regarding daily activity levels, frequency of footcare and self-care. Additionally, multiple consecutive thermographic and SFPPP measurements were not performed to assess for inflammation. Due to the study design, the causal relationship between factors and outcomes could not be postulated and due to subjects resting for at least 15 minutes before thermography, it would be intriguing and potentially more valid to examine for callus hotspots immediately after exercise and the time taken for these to return to resting values.
Despite these limitations, it is an interesting study which raises some interesting questions from clinical, research and educational perspectives, thus, it would be a good read for those seeking professional development. It also underlines the importance of identifying those who are at most risk of ulceration and provides markers for prevention.
Qin Q, Oe M, Ohashi Y et al (2021) Factors associated with the local increase of skin temperature, ‘hotspot,’ of callus in diabetic foot: a cross-sectional study. J Diabetes Sci Technol May 20; 19322968211011181
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