Relationship between sagittal plane kinematics, foot morphology and vertical forces applied to three regions of the foot

Kinetic analysis of human motion with a multi-segment musculoskeletal foot model requires the distribution of loading applied to the modeled foot segments to be determined. This work thus examines the existence of any correlation between intersegmental foot kinematics, foot morphology, and the distribution of vertical loading in a multi-segment foot model. Gait analysis trials were performed by 20 healthy subjects at a self-selected speed with intersegmental foot joint angles and the distribution of vertical loading measured for a multi-segment foot model. A statistical relationship between the sagittal plane foot kinematics and loads applied to each foot sub-area was sought using multiple regression analyses. The sub-segmental loading of the normal and abnormal morphological groups was also compared. No meaningful relationships between sagittal plane foot kinematics and sub-segment foot loading were found (max. R2 = 0.36). Statistically significant relationships between foot morphology classification and sub-area foot loading were however identified, particularly for feet exhibiting hallux valgus. Significant variation in inter-subject foot sub-segmental loading indicates that an appropriate technique for determining this load distribution must be determined before effective kinetic analyses are performed with multi-segment musculoskeletal foot models. The results of this study suggest that foot morphology is a better indicator of sub-area loading than sagittal plane kinematics and warrants further investigation.