Sensor-Assisted Wound Therapy in Plantar Diabetic Foot Ulcer Treatment: A Randomized Clinical Trial

Abstract

Background: Offloading is the cornerstone of treatment of plantar diabetic foot ulcers. It limits mobility with consequent psychological and cardiovascular side effects, and if devices are removed, healing is delayed.

Methods: We developed three non-removable techniques with increasing offloading potential (multilayer felt sole, felt-fiberglass sole, or total contact casts with ventral windows) and sensors built within. Smartwatch and web apps displayed pressure, temperature, humidity, and steps. They alerted patients, staff, and a telemedicine center when pressure limits (125 kPa) were exceeded. Patients were advised to walk as much as they had done before the ulcer episode. To evaluate the potential of this intervention, we enrolled 20 ambulatory patients in a randomized clinical trial. The control group used the same offloading and monitoring system, but neither patients nor therapists received any information or warnings.

Results: Three patients withdrew consent. The median time to healing of ulcers was significantly shorter in the intervention group compared with controls, 40.5 (95% confidence interval [CI] = 28-not applicable [NA]) versus 266.0 (95% CI = 179-NA) days (P = .037), and increasing ulcer area was observed less frequently during study visits (7.9% vs 29.7%, P = .033). A reduction of wound area by 50% was reached at a median of 10.2 (95% CI = 7.25-NA) versus 19.1 (95% CI = 13.36-NA) days (P = .2). Participants walked an average of 1875 (SD = 1590) steps per day in intervention group and 1806 (SD = 1391) in the control group.

Conclusions: Sensor-assisted wound therapy may allow rapid closure of plantar foot ulcers while maintaining patient's mobility during ulcer therapy.

Keywords: diabetic foot syndrome; diabetic foot ulcer; offloading device; sensor-assisted wound therapy; sensors; total contact cast.

Figure 1.

(a) Electronics and (b) housing of the small and flexible sensor unit. (c) Fif!-mobile device integrating the sensor unit, visible at the base of the cutout, and its use. (d) Patients wear an offloading device integrating the sensor unit. They also wear a smartwatch receiving and displaying data from the sensor unit and possibly alarms. Via mobile Internet, sensor data are sent to the iFoot database and are displayed together with medical data concerning the diabetic foot ulcer. The database application may send alarms to the diabetic foot clinic and to the telemedicine center. Staff at the clinic or at the telemedicine center may communicate with the patient about the findings and what might be the case to do.

Figure 2.

Flowchart of the profile of the study. Abbreviation: PAD, peripheral arterial disease; CN, charcot neuroosteoarthropathy.

Figure 3.

Probability of healing by (a) 50% or (b) complete over time.

Figure 4.

Treatment and sensor readings of a 57-year-old blue-collar worker with an ulcer of 2.04 cm² located beneath the fifth MTH. (a) Ulcer at the beginning of sensor-assisted wound therapy. (b) Offloading as standardized for ulcers at the fifth MTH. (c) Second study visit after four weeks. According to the patient, the ulcer closed one week before this visit. (d) Steps per day ranging from approximately 1000 to 4800. (e) Temperature measurements. During the dressing change, the sensor was placed on a radiator. (f) Humidity was 100% during most of the time. (g) Pressure readings. The vertical lines are the maximum pressure values in an interval of 10 minutes; green if below the threshold of 125 kPa; red if above. Abbreviation: MTH, metatarsal head.