Changes in the thickness and stiffness of plantar soft tissues in people with diabetic peripheral neuropathy

Objective: To compare the thickness and stiffness of plantar soft tissues between people with diabetic peripheral neuropathy (DPN) and healthy subjects. Design: Cross-sectional study. Setting: University research laboratory. Participants: Subjects with DPN (n=70 [35 men, 35 women]; mean age ± SD, 65.4±8.6y) and healthy control subjects (n=54 [12 men, 42 women]; mean age ± SD, 57.9±6.1y) were recruited. Interventions: Not applicable. Main Outcome Measures: The thickness and stiffness of the plantar soft tissues were measured by the tissue ultrasound palpation system over the pulp of the big toe (BT), first metatarsal head (MTH), second MTH, and the heel. Results: No significant difference in the thickness of the plantar soft tissues was found in any measurement site between the diabetic group and control group. The plantar soft tissues of the DPN group were significantly stiffer than those of the control group at the BT (85.29kPa vs 50.49kPa), first MTH (96.29kPa vs 62.05kPa), second MTH (84.77kPa vs 52.93kPa), and the heel (65.62kPa vs 44.95kPa) (all P<.01). Conclusions: People with DPN tend to have stiffer plantar tissues than do healthy control subjects. The stiffer plantar soft tissues may reduce the cushioning effects of the foot during walking for people with DPN.