1. Digital thermographic imaging – a novel monitoring approach in Charcot neuroarthropahy with potential clinical usefulness
Josephine Bigeni1,2, Carl Azzopardi3, Sandro Vella1,2, Yves Muscat-Baron4,5, Kenneth P Camilleri3,6, Mario J Cachia1,2
1Diabetes and Endocrine Centre, Mater Dei Hospital, Msida, Malta
 2Department of Medicine, University of Malta Medical School, Msida, Malta
3Centre for Biomedical Cybernetics, University of Malta, Msida, Malta
4Department of Obstetrics and Gynaecology, Mater Dei Hospital, Msida, Malta
5Department of Obstetrics and Gynaecology, University of Malta Medical School, Msida, Malta 6Department of Systems and Control Engineering, Faculty of Engineering, University of Malta, Msida, Malta
Background:
Charcot neuroarthropathy is a chronic disabling arthropathy complicating peripheral neuropathy, often in the setting of diabetes. Establishing a definitive diagnosis is challenging and largely clinical. Recovery is often protracted, and difficult to monitor clinically, given paucity of clinical signs and symptoms, and non-specific data borne out of established investigative tools. Strict off-loading of the affected joint(s) (commonly the ankle and / or foot) constitutes the cornerstone of clinical management, although there is currently mounting clinical evidence supporting a role for adjunct bisphosphonate and calcitonin therapy.
Asymmetric temperature differences secondary to inflammation within the affected joint(s) is a hallmark of this disease entity, classically presenting with a temperature difference of over 2°C compared with the unaffected contralateral joint. Temperature differences correlate highly with radiographic changes and with markers of bone turnover, and may antedate clinical presentation and foot ulceration. Infrared thermography potentially offers a relatively simple, non-contact, non-ionizing, relatively inexpensive and rapid, method of monitoring healing (‘foot cooling’) and recurrence (‘foot warming’) in the same or contralateral foot.
Method:
We investigated serial dorsal and plantar thermographic images from a 58 year old lady known to suffer from type 1 diabetes, who presented to our diabetes foot services clinic with acute Charcot foot, illustrating response to treatment with off-loading and intravenous pamidronate. Thermographic images were taken at 3 week intervals. These were always preceded by a 10 minute acclimatization period which was achieved by leaving the affected foot without a cast and the normal foot without sandals.
Results:
There was a drop of peak temperature of dorsal and plantar aspect of the affected foot of 1.34°C and 2.93°C respectively. However the most significant drop was on the 18th September (3months after treatment was commenced) with a drop of peak temperature of dorsal and plantar aspect of the foot of 4.13°C and 3.04°C respectively.
The difference between the affected and unaffected foot increased 5 months into the treatment. A raise in affected foot temperature occurred when the patient started to teach again at 3 months.
Limitations
This is a one case study and another limitation might have been that the 10 minute acclimatization period might not have been enough.
Conclusion:
This case report illustrates the potential usefulness of thermography as a non invasive way of following up patients with acute Charcot. The temperature changes seem to follow the improvement in inflammation of the foot. This is further illustrated by the increased temperature once the patient went back to work. This is a relative novel, non-invasive technique which is potentially useful to determine the progress of Charcot foot
References:
K Roback. An overview of temperature monitoring devices for early detection of diabetic foot disorders, 2010, Expert review of Medical devices, (7),5,
DG Armstrong, LA Lavery. Monitoring healing of acute Charcot`s arthropathy with infrared dermal thermometry. Jouranl of Rehabilitation Research and Development 1997: 34 (3);
Figure 1: Dorsal peak temperature
Figure 2: Plantar peak temperature
1 month after treatment was started
3months after treatment was started
5 months after treatment was started