Author: Antony N. Davies – Sustainable Environment Research Centre (SERC) at University of South Wales, UK and Thermetrix, Wales.
It is well known in scientific literature that foot temperature can be a very useful non-invasive indicator of underlying foot health (Fig. 1). Many studies have proven that if the feet of high-risk patients are scanned frequently, it is possible to pick up signs of developing diabetic foot ulcers in time to put interventions in place to avoid their further development. The arguments for more widely deploying thermography have led recently to the Royal College of Podiatry assessing and professionally approving the Thermetrix Podium foot imaging system. Indeed Natasha Smith, Business Development Manager at the Royal College of Podiatry, stated:
“I am delighted to welcome Podium Professional to our range of Professionally Approved products. The team at Thermetrix has a clear goal of improving lower limb health through detection, prevention and early intervention which aligns with the College’s goals.”
Figure 1: Two sets of feet imagery with equal (left) and unequal (right) thermography profiles. Minor differences are normal but the large difference in the patient on the right are a clear indication of significant problems within the foot.
Studies, trials, and academic research are all well and good but what happens when a new technology such as high-resolution thermal imagery is deployed into the real world of normal patient care without the careful screening of patient populations and measurement environments?
Two recent case studies involved the use of Podium where patients had their feet scanned in addition to their normal health assessments to determine the additional value of thermography over current best practice. In Germany, Dr med Thomas Werner, head of the Diabetic Clinic in Bad Lauterberg, introduced scanning of their in-patients in January 2023 and had scanned more than 150 patients by the end of March. In Bermuda, where there is a particularly serious level of diabetes in the population, the Bermuda Health Council (BHEC) funded a thermography pilot study as part of its Chronic Disease Innovation Programme. Four Podium devices were deployed to two different clinical settings under the project leadership of Dr Kyjuan Brown, Medical Director of Northshore Medical Center, with Dr Neil Moncreiff, Podiatrist and owner of Bermuda Podiatry Centre (Fig. 2). Dr Moncrieff picked up on the Podium motto of ‘Scan Feet, Save Limbs, Save Lives’ in his commentary on the success of the pilot study:
“Using the Podium Professional in clinic has meant that some of our patients have successfully avoided their condition developing to surgical intervention. Scanning feet really does save lives.”
Figure 2, Logo of the Bermuda Health Council funded thermography study.
This avoidance of foot problems developing to such a level that surgical intervention is required was one of the core messages from the Bermuda pilot study, which led to the BHEC requesting a detailed sustainability plan for the wider routine deployment of high-resolution thermography across the island.
Assessing Foot Temperature Imagery
One of the early teachings for those assessing thermal foot imagery is to remember that as feet are on the periphery of the human body, the absolute temperature of the feet is, by itself, not very relevant for foot health assessment. Your feet can vary by a surprisingly large amount compared to your more tightly regulated core body temperature. What is useful is to compare the relative temperature profiles of your feet against one another as shown in Fig. 1. Known as contralateral asymmetry, if the feet show significant differences in their thermal images of more than a couple of degrees can be used to indicate an underlying pathological process requiring further investigation. In healthy feet there is also a significant temperature gradient between the middle of the foot and the toes and heels – should this gradient be inverted or absent this is also an indicator of a clinically relevant problem.
Individual hotspots can indicate localised inflammation which if due to subcutaneous tissue damage from overloading or badly fitting footwear, can signal the start of a diabetic foot ulcer before any signs are visible on the surface inspection of the foot. This damage can go unnoticed by someone suffering from diabetic neuropathy. In contrast, unusual cold areas showing up in the scans can indicate perfusion disorders such as macro or microangiopathy.
In Germany, Dr Werner’s team continues to assess patient feet using thermography and in a recent article in the German magazine Diabetes Forum, Dr Werner highlighted that temperature alone is essentially a function of blood flow and not specific to any particular illness or complaint. His example was of a hot big toe, clearly showing up on a thermal image, flagging the area for further investigation – but which might turn out to be an ingrowing toenail, a fracture, a foreign body or the first stages of a diabetic ulcer caused by badly fitting footwear.
Assessing Thermography Deployment
Although the experiences mentioned here related to Podium devices successfully deployed in clinical settings, many of the scientific literature papers, particularly from the USA, are from deployments into a home setting. In this setting, it is much simpler to carry out a high frequency of thermal scans so the likelihood of catching a developing ulcer is significantly greater than when diabetic foot assessments are widely spaced. Dr Werner has pointed out that for patients where no previous recorded history of diabetic foot syndrome in the patient notes, thermographic imagery pointed towards a suspected peripheral polyneuropathy, and additional diagnostics were initiated. These almost always confirmed the presence of polyneuropathy, and in one case a specific perfusion problem was identified which was not the result of peripheral arterial disease. This clear ability to support diagnoses of diabetic foot syndrome will mean that foot examinations for these patients will now be much more frequent.
In Bermuda, one of the critical factors in getting approval for the thermography study was the ability to deploy the technology so that equal access was available across the island for all people suffering from diabetes. In the UK, early adopter podiatrists are already using the Podium system to support their work and are also finding the scan reports useful in getting urgent patient referrals through GPs into specialist clinics.
The impact of thermal images on patient compliance
Regardless of whether the Podium thermography system has been deployed in Australia, the Americas, Europe or here in the UK, all users have reported the extra impact being able to visualise the foot problem in full colour imagery has on the patients. The visual imagery strongly supports the often dry messaging about off-loading, use of creams, use of orthotics and the importance of continuing with these treatments even long after, for example, when a patient is released back into primary care and a foot ulcer appears to have healed over. Far too often a patient can, at enormous cost to the health service, undergo many months or years of specialist treatment only to return to hospital a few months after release to primary care with a fresh or returning ulcer needing additional surgery as they have failed to comply with their long-term health advice. For the very stretched UK NHS trust budgets, the ability to permanently interrupt this vicious circle or even delay the patient’s return to relieve pressure on waiting lists, could well be the key to much wider deployment.
For more information including case studies and testimonial videos from early adopters deploying the Podium into clinical practice see: https://podium.care