A Comprehensive Biomechanical Assessment of Foot Function in People with Diabetes Mellitus and Peripheral Neuropathy

Thesis (Ph.D.)--University of Rochester. School of Nursing. Dept. of Health Practice Research, 2015.Purpose: To date, individual metatarsal motion or multi-joint power and work have not been assessed in people with diabetes mellitus and peripheral neuropathy (DMPN). The purpose of this study was to apply a novel multi-segment biomechanical foot model to comprehensively assess foot function in people with DMPN in order to advance understanding regarding the potential factors that contribute to foot ulceration. Methods: Fifteen people with DMPN and 15 healthy matched control (MC) participants were recruited for this case-control study. A six-segment foot model (tibia, calcaneus, middle cuneiform, 1st, 3rd and 5th metatarsals) was employed to measure multi-segment kinematic angular excursions and multi-joint kinetics, in the form of midfoot (MF) and rearfoot (RF) power, work and the ratio of negative work to total work (negative work ratio), during walking at predetermined speeds. Forefoot pressure time integral (PTI) was also assessed during walking at the same controlled speeds. Student t-tests were used to evaluate group differences in kinematics and kinetics, and Pearson correlations were used to explore the associations between these variables and PTI. Results: There was a reduction of sagittal and transverse plane excursion at all individual metatarsals in the DMPN group in comparison to the MC group (all p ≤ 0.02). The exception was observed in first metatarsal transverse plane excursion, where there was a minimal between group difference (p = 0.53). DMPN MF and RF kinetic function were both characterized by a significant reduction of peak power generation and an increase in peak power absorption in comparison to the MC group (all p ≤ 0.05). The negative work ratio was at least 10% greater in the DMPN group at both the MF and RF (p = 0.12 and p < 0.00, respectively). MF negative work ratio accounted for 16% and 14% of the variance in forefoot PTI in the DMPN group and in the entire sample, respectively. Conclusions and Clinical Implications: This study documents a clearly different and previously unidentified foot function profile that may better explain the progression of pathologies afflicting people with DMPN. Specifically, MF negative work ratio may represent a new target variable for footwear and rehabilitation strategies aimed at the prevention of DMPN plantar tissue breakdown