Background
Elevated plantar pressures have been implicated in the development and non-healing of foot ulcer in people with diabetes. Limited ankle dorsiflexion, or equinus, has been associated with elevated plantar pressures. This trial investigated if a stretching intervention could increase ankle dorsiflexion and reduce plantar pressures in people with diabetes.
Methods
Two-arm parallel randomised controlled trial at an Australian university podiatry clinic. Adults with diabetes and ankle equinus (≤ 5 degrees dorsiflexion) were randomly allocated to receive an eight-week calf stretching intervention (n=34) or continue with their normal activities for eight weeks (n=34). Primary outcomes were weight bearing and non-weight bearing ankle dorsiflexion range of motion and forefoot peak plantar pressures. Secondary outcome measures were forefoot pressure time integrals and adherence to the stretching intervention. Differences between groups were analysed with analysis of covariance.
Results
68 adults (mean (SD) age and diabetes duration 67.4 (10.9) years and 14.0 (10.8) years, 64.7% male) were recruited. Following the intervention, no significant differences were found between groups for ankle dorsiflexion either non-weight bearing (adjusted mean difference +1.3 degrees, 95% CI:-0.3 to 2.9, p=0.101) or weight bearing (adjusted mean difference +0.5 degrees, 95% CI:-2.6 to 3.6, p=0.743). No differences were found for forefoot in-shoe (adjusted mean difference 1.5kPa, 95% CI -10.0 to 12.9, p=0.803) or barefoot peak pressures (adjusted mean difference -19.1kPa, 95% CI:-96.4 to 58.1, p=0.628). Additionally no significant reductions in forefoot pressure time integrals were identified. Seven (20.6%) of the intervention group and 2 (5.9%) of the control group were lost to follow up.
Discussion and Clinical Relevance
Our data failed to show a statistically or clinically significant meaningful effect of calf muscle stretching on ankle range of motion, or plantar pressures, in people with diabetes and ankle equinus. Diabetes related changes to muscle-tendon or neural structures may make stretching less effective in this group. While current guidelines, including those from the American Diabetes Association, recommend stretching to maintain joint range of motion in people with diabetes, it is not effective as a stand-alone therapy to increase ankle joint range of motion in this population.