Heel Rise and Non–Weight-Bearing Ankle Plantar-Flexion Tasks to Assess Foot and Ankle Function in People With Diabetes Mellitus and Peripheral Neuropathy

Objective To examine the effects of diabetes mellitus and peripheral neuropathy (DMPN), limited joint mobility, and weight bearing on foot and ankle sagittal movements; and characterize the foot and ankle position during heel rise. Methods Sixty people with DMPN and 22 controls participated. Primary outcomes were foot (forefoot on hindfoot) and ankle (hindfoot on shank) plantar-flexion/dorsiflexion angle during three tasks: unilateral heel rise, bilateral heel rise, and non–weight-bearing ankle plantar flexion. A repeated measures analysis of variance and Fisher exact test were used. Results Main effects of task and group were significant, but not the interaction in both foot and ankle plantar flexion. Foot and ankle plantar flexion were less in people with DMPN compared to controls in all tasks. Both DMPN and control groups had significantly less foot and ankle plantar flexion with greater weight bearing, however, the linear trend across tasks was similar between groups. The DMPN group had a greater percentage of individuals in foot and/or ankle dorsiflexion at peak unilateral heel rise compared to controls, but the foot and ankle position was similar at peak bilateral heel rise between DMPN and control groups. Conclusions Foot and ankle plantar flexion is less in people with DMPN. Less plantar flexion in non–weight bearing suggests that people with DMPN have limited joint mobility. However, peak unilateral and bilateral heel rise is less than the available plantar-flexion range of motion measured in non–weight bearing indicating that limited joint mobility does not limit heel rise performance. A higher frequency of people with DMPN are in foot and ankle dorsiflexion at peak unilateral heel rise compared to controls, but the position improved with lower weight bearing. Impact Proper resistance should be considered with physical therapist interventions utilizing heel rise because foot and ankle plantar-flexion position could be improved by reducing the amount of weight bearing.