Experimental modeling and biomechanical measurement of flatfoot deformity

Treatment of the flatfoot requires a quantitative understanding of the biomechanical factor on this common deformity. Seven unembalmed foot-ankle complex specimens were used in this study to model experimental flatfoot deformity by release of plantar fascia, spring ligament, long and short plantar ligaments. Digital speckle correlation method (DSCM) and strain gauges were applied to measure displacements and strains of specimens before and after ligaments resection. Acquired data were compared with each other and statistically analyzed. Results of this experiment showed different appearance of foot-arch according to release of different ligament or complex. Obvious flatfoot deformity appeared only after at least three of the four main ligaments were cut off. Under the condition that four ligaments were completely released, the arch height decreased, longitudinal arch prolonged, forefoot abduced, force in various tissues redistributed, and center of bearing shifted forwards. This method is suitable for constructing experimental model of flatfoot deformity. This study accumulated large amounts of data for further research.