Variability in Activity May Precede Diabetic Foot Ulceration

Armstrong DG, Lavery LA, Holtz-Neiderer K, Mohler MJ, Wendel CS, Nixon BP, Boulton AJ. Diabetes Care. 2004;27:1980-1984.

The involvement of repetitive stress through daily activity in the development of foot ulceration has not been widely studied, primarily because of the difficulty of measuring and evaluating daily activity. However, recent advances in activity monitoring devices have made the assessment of daily activity possible. The purpose of this prospective longitudinal study was to determine if there were differences in activity profiles of patients with diabetes who developed neuropathic foot ulceration compared with those of similar risk who did not develop foot ulceration.

In total, 100 patients with diabetes and concomitant neuropathy, deformity, and/or history of lower-extremity ulceration/partial foot amputation were evaluated. Subjects were drawn from an ongoing prospective longitudinal activity study and selected based on the first 100 consecutive patients who met the inclusion criteria. Individuals with concomitant peripheral vascular disease were excluded from the study. Baseline characteristics were 95.0% male (n=95); mean age: 68.5 years; mean duration of diabetes: 13.7 years; and mean BMI: 30.0 kg/m².

Upon enrollment, all patients underwent a standard diabetic foot evaluation and received physician-approved over-the-counter footwear with pressure-relieving insoles or prescriptive depth inlay shoes, as selected by the clinician. Patients also received a high-capacity, continuous, computerized activity accelerometer/pedometer, which they were instructed to wear at all times throughout the study period. The monitor measured both the number of steps taken over a period of time and the time at which each step occurred, and was used to identify clusters of activity. Data were collected during preventive foot care visits carried out every 2 to 3 months over a minimum study period of 25 weeks (mean: 37.1 weeks) or until the occurrence of ulceration.

During the evaluation period, 8 patients (8%) developed ulceration in the plantar forefoot. These patients had significantly lower daily activity compared with subjects who did not develop foot ulceration (809.0±612.2 vs 1394.5±868.5, respectively; P=0.03). Patients with ulceration had significantly greater variability in activity compared to those without ulceration (96.4±50.3% vs 44.7±15.4%, respectively; P=0.0001), and this variability further increased 2 weeks prior to the ulceration event (115.4±43.0%; P=0.02). However, there was no significant difference in average daily activity during this 2-week period (P=0.5).

In summary, individuals with diabetes may have decreased activity preceding the development of foot ulceration compared with those who do not develop foot ulceration. Furthermore, the quality of activity may be more variable just prior to the development of foot ulceration. This is the first study to evaluate the effect of activity on foot ulceration in patients with diabetes using an activity monitoring device and could have future implications for preventive interventions in foot care, such as the development of devices that provide patients with feedback to help them maintain a consistent level of safe activity, thereby decreasing the risk of ulceration.