Medio-lateral forefoot segmentation for clinical gait analysis based on metatarsal subunit rigidity and angular...

Although there is general agreement about the longitudinal division of the foot into segments for clinical gait analysis, there is limited evidence on which to base decisions about mediolateral segmentation, particularly in the metatarsal region.

We investigate how best to divide the metatarsals mediolaterally by considering both segment rigidity and angular motion.

Motion capture data were collected on 45 healthy adults during barefoot walking. The rigidities of ten subunits of adjacent metatarsals were quantified. Segment axes were defined for a selection of subunits and their three-dimensional angular motions calculated relative to an Oxford Foot Model (OFM) hindfoot segment.

Subunits of metatarsals 2-3 and 3-4 were equally the most rigid, followed by subunit 2-3-4. Medial metatarsal groups were more rigid than lateral groups. Model A (metatarsal subunits 1-2-3 & 4-5), Model B (1-2 & 3-4-5), and Model C (1& 2-3-4 & 5) all had angular motion significantly different from the OFM forefoot for most of the gait cycle. There were significant differences between the motions of the medial and lateral subunits of Models A and B. The central subunit of Model C moved more like the medial subunits in dorsiflexion and more like the lateral subunits in adduction.

The forefoot models examined represent the minimum complexity required to capture metatarsal motion during walking. A mediolateral division of the forefoot at or adjacent to the third metatarsal is one option. The alternative is a three-segment model with a central subunit and separate first and fifth metatarsals.