Smita Rao, Charles Saltzman, H. John Yack

Introduction
The purpose of our study was to examine the relationship between ankle dorsiflexion (DF) range of motion (ROM) and stiffness measured at rest (passively) and plantar loading during gait in individuals with and without diabetes mellitus (DM) and sensory neuropathy. Specifically, we sought to address three questions for this at-risk patient population: (1) Does peak passive DF ROM predict ankle DF ROM used during gait? (2) Does passive ankle stiffness predict ankle stiffness used during gait? (3) Are any of the passive or gait-related ankle measures associated with plantar loading?

Methods
Ten subjects with DM and 10 age and gender matched non-diabetic control subjects participated in this study. Passive ankle DF ROM and stiffness were measured with the Iowa Ankle ROM device. Kinematic, kinetic and plantar pressure data were collected as subjects walked at 0.89 m/s.

Results
We found that subjects with DM have reduced passive ankle DF ROM and increased stiffness compared to non-diabetic control subjects, however, subjects with DM demonstrated ankle motion, stiffness and plantar pressures, similar to control subjects, while walking at the identical speed, 0.89 m/s (2 mph). These data indicate that clinical measures of heel cord tightness and stiffness do not represent ankle motion or stiffness utilized during gait. Our findings suggest that subjects with DM utilize strategies such as shortening their stride length and reducing their push-off power to modulate plantar loading.