This jig is designed to measure the flexibility of the first metatarsophalangeal joint (MTPJ). After securing the subject’s foot in the device, the operator rotates the plate secured to the big toe toward the top of the foot while moment and angle data are collected.
The data are acquired with the LabVIEW data acquisition system at 200 Hz. The flexibility of the first metatarsophalangeal joint is estimated as the slope of the moment versus angle curve. A sample analysis is shown in the figure below. Three parameters are calculated from the curve: early flexibility, late flexibility, and laxity (i.e. the resulting angular excursion for a fixed input moment).