Recent studies on the diabetic foot syndrome

Question
In line with a prospective study on the effectiveness of treatments with shoes as recurrence prophylaxis of neuropathic plantar pressure ulcers, different risk factor for ulcer recurrences should be examined, such as the extent of the foot deformity, the existence of calluses, the pressure load of the foot when walking barefoot and when walking in prescribed shoes, the daily walking distance and its variation as well as the actual wear period of the prescribed shoes.

 

Patients and methods
In this multicenter, randomized study 171 patients with a recently healed, neuropathic plantar ulcer wereincluded. The study was carried out in 10 outpatient centers for diabetic feet in the Netherlands. Included were patients that had a healed plantar ulcer in a period of less than 18 months before the beginning of the study. All patients had a peripheral diabetic polyneuropathy, proven with the help of a 10g-monofilament and a vibration test. The follow-up examination period was 18 months.
All patients received ready-made or custom-made special shoes with custom-made footbeds. Initially the pressure load was measured when walking barefoot (E-med, Novel, Munich) and every 3 months the dynamic pressure load in the prescribed shoes (Pedar, Novel) was measured. The actual wear period of the shoes was measured with the help of a sensor fixed in the shoe (@monitor, Academic Medical Centre, Amsterdam). The number of daily steps was detected over the same period of time with an activity monitor (Step-Watch, Orthocare, Oklahoma City).
Furthermore multiple demographic and disease-specific factors were collected. The existence of foot deformities was also collected and classified as not existing, slight, moderate or severe according to the severity. Non-ulcerative foot lesions such as calluses, blisters and dermatorraghias were collected initially and every three months. Additionally the frequency of podiatric treatments was documented during the follow-up examination. The patients received a follow-up examination over a period of time of 18 months. The primary final point was the occurrence of a plantar ulcer. Logistic regression analyses were carried out, in order to detect independent risk factors for the occurrence of plantar ulcers in this high risk group. Additionally a second analysis followed considering those patients that had an ulcer recurrence at the spot of the healed ulcer.

Results
Of the 171 patients, 71 developed a plantar foot ulcer, after a median period of time of 5.1 months (25–75-percent-quartile, 2.8–9.4 months). 41 of 71 ulcers developed as a consequence of unnoticed repetitive pressure load in the area of the earlier ulcer. They occurred already after a median period of time of 3.9 months (2.5 – 8.9 months).
Of the patients who developed an ulcer, 45 percent showed non-ulcerative lesions when they were included in the study, whereas this only occurred with 18 percent of patients who did not develop an ulcer. With ulcer recurrences at the same localization this difference was even stronger with 63 percent versus 15 percent. In 23 of the 71 ulcers a non-ulcerative lesion was seen at the spot where there was an ulcer detected during the next follow-up examination. In the multi-variant analysis the existence of non-ulcerative lesions was the biggest risk factor with an odds ratio (OR) of 9.06 percent (95 percent CI, 2.98-27.57). The longer existence of a pre-ulcer also was a significant risk factor, but only with a low OR of 1.03.
A significant factor that protected against the development of an ulcer was a high variability of the daily walking distance OR 0.93.
With the 41 ulcer recurrences at the same spot also the non-ulcerative lesions were the strongest risk factors (OR 10.95), apart from that also increased pressure when walking barefoot was significant (OR 1.11). Protective from an ulcer was again a high variability of the daily walking distance (OR 0.91), but the main effect was the regular wearing (>80 percent) of effective shoes, reducing the peak pressure to < 200 kPa (OR 0.43).

Conclusions
The authors conclude from their data that calluses, dermatorraghia and blisters are highly significant for the prediction which patients develop a foot ulcer. The regular wearing of effective shoes on the other hand reduced the risk of an ulcer recurrence by about 50 percent. These data show that well manufactured footbeds are an effective measure for recurrence prophylaxis of neuropathic plantar ulcers. A regular screening for non-ulcerative skin lesions has a high sensitivity to recognize patients with an extraordinary risk for an ulcer and to take the corresponding shoe-technical and podiatric measures.

Commentary
This extraordinarily important study by the group of Sicco Bus quantified for the first time risks for the occurrence of ulcer recurrences under consideration of many demographic and disease-specific factors. Additionally also the treatment with shoes, the pressure load and first of all the wearing of effective shoes were considered. Also in this study it was shown that plantar ulcer recurrences are extremely frequent and that they occur not long after the healing of the previous ulcer. Furthermore this study proves that effective shoes and the treatment of non-ulcerative skin lesions are effective measures to reduce this strong risk for our patients.
Also it is shown here that such a high risk group needs foot exams much more frequently than what is done nowadays and that a tight connection to a specialized outpatient clinic is decisive for the reduction of the rate of ulcer recurrences. Maximilian Spraul

References
Waaijman R, de Haart M, Arts MLJ, Wever D, Verlouw AJWE, Nollet F, Bus SA: Risk Factors for Plantar Ulcer Recurrence in Neuropathic Diabetic Patients. Diabetes Care 37,1697-1705, 2014

Assessing Patients Adherence to Costumized
Diabetic Insoles for
By Wolfgang Best
Background: International guidelines strongly recommend the use of customized diabetic footwear and insoles for people with diabetes at risk for diabetic foot problems in order to reduce the mechanical stress by redistributing pressure to the plantar tissue. Recent studies suggest that adherence to footwear and insoles which offload the foot is associated with the prevention and healing of diabetic foot ulcers. However, little is known about the long-term course of adherence in patients at risk for diabetic foot problems.
Method: In this study a temperature sensor was incorporated into the specialized footwear of patients with type 2 diabetes after their first plantar ulceration. The wearing time was monitored by measuring the temperature inside the footwear every 15 minutes. 26 patients with a mean observation time of 133.5 days could be analyzed.
Results: Mean wearing time of diabetic footwear was between 4.2 and 3.6 h/day. But data analysis showed, that on 51% of the days patients did not wear their footwear at all. A closer look at the data revealed that adherence to the footwear dropped after a couple of weeks. Men achieved a mean time of adherence of 30.5 weeks, while women only achieved 14 weeks. The mean time of adherence was 27.5 weeks.
Conclusions: The results suggest that the overall wearing time was rather low as patients have only worn their footwear for about 4 hours a day and did not put it on at all on more than 50 % of the days. As footwear can only help reduce stress on tissue when it is worn, the authors conlude that the long term effect of diabetic footwear can be questioned. However, no reulceration occurred during the observation period.

Commentary:
This study shows that adherence is not an “add on” but should be in the center of attention when providing specialized footwear for people with diabetic foot problems. Further investigations should also focus on reasons for adherence and non-adherence. Achieving better adherence is a challenge. Education on the importance of adequate footwear that incorporates personal perceptions, values and experiences of the patients will play an important role in this task.

Reference:
Ehrmann Dominic, Spengler Monika, Jahn Michael, Dipl, Niebuhr Dea, Haak Thomas, Kulzer Bernhard, Hermanns Norbert: Adherence Over Time: The Course of Adherence to Customized Diabetic Insoles as Objectively Assessed by a Temperature Sensor.
Journal of Diabetes Science and Technology 1–6, December 27, 2017

Prof. Maximilian Spraul is an expert in diabetes. He is head physician at the Medical Clinic in Rheine/Germany and is a member of the Diabetic Foot Study Group.
Wolfgang Best is editor of foot&shoe.