Individual metatarsal and forefoot kinematics during walking in people with diabetes mellitus and peripheral neuropathy

•We examined kinematics of both individual metatarsals (1,3,5) and a unified forefoot segment.•Sagittal plane motion was reduced in all examined segments in people with diabetic neuropathy.•Forefoot segment not representative of metatarsal motion in the frontal and transverse planes.•Individual metatarsal kinematics provides further insight into the diabetic neuropathic process.

The purpose of this study was to compare in-vivo kinematic angular excursions of individual metatarsal segments and a unified forefoot segment in people with Diabetes Mellitus and peripheral neuropathy (DMPN) without deformity or ulceration to a healthy matched control group. Thirty subjects were recruited. A five- segment foot model (1st, 3rd, and 5th metatarsals, calcaneus, tibia) was used to examine relative 3D angular excursions during the terminal stance phase of walking. Student t-tests were used to assess group differences in kinematics. Pearson correlations and cross-correlations were used to assess relationships between the motion of the individual metatarsals and the unified forefoot. Significant reductions of DMPN group sagittal plane angular excursions were detected in all individual metatarsals and the unified forefoot (p < 0.01). Frontal plane 3rd metatarsal excursion was reduced (p = 0.04) in the DMPN group. The 3rd and 5th metatarsal and the unified forefoot excursions were reduced (p ≤ 0.02) in the DMPN group in the transverse plane. In both groups, coupling of individual metatarsal and unified forefoot motion was strongest in the sagittal plane. This study illustrates that multiple individual metatarsals have reduced motion in people with DMPN. Differences in the magnitude and coupling between individual metatarsal motion and unified forefoot motion supports the use of a two segment forefoot modeling approach in future kinematic analyses. Further study is recommended to determine if the observed kinematic profile is related to the development and location of deformity and tissue breakdown in people with DMPN.