Do the biomechanical properties of the ankle-foot complex influence postural control for people with Type 2 diabetes?

Background: The ankle-foot complex plays an important role in the mechanics of postural control. The objectives of this study were to compare the biomechanical properties of the ankle-foot complex of people with diabetes who had or did not have peripheral neuropathy with those healthy individuals; and to examine its correlation with postural control. Methods: A total of 64 individuals participated in this study: 9 people with diabetic peripheral neuropathy, 23 diabetes without neuropathy, and 32 healthy controls. A hand-held ultrasound indentation system was used to assess the soft tissue biomechanical properties of the ankle-foot complex. The Sensory Organization test was performed using The Smart EquiTest system to assess postural control. Findings: The soft tissue of the Achilles tendon was significantly thickened in all individuals with diabetes (P < 0.001), and was associated with the vestibular ratio (r = 0.40; P < 0.05). The Young's modulus of the plantar soft tissue was significantly increased in the diabetic neuropathy group (all P < 0.05). Also, the Young's modulus of the plantar soft tissue at the first metatarsal head was positively correlated with the somatosensory ratio (r = 0.46; P < 0.05) and visual ratio (r = 0.39; P < 0.05). Interpretation: Diabetic patients with or without neuropathy had a thicker Achilles tendon and stiffer plantar soft tissue than the healthy control. Changes in the biomechanical properties of the ankle-foot complex were correlated with the use of vestibular, somatosensory or visual inputs to maintain balance in individuals with diabetes.