Cadaveric simulation of a pes cavus foot

The pes cavus deformity has been well described in the literature; relative bony positions have been determined and specific muscle imbalances have been summarized. However, we are unaware of a cadaveric model that has been used to generate this foot pathology. The purpose of this study was to create such a model for future work on surgical and conservative treatment simulation.

We used a custom designed, pneumatically actuated loading frame to apply forces to otherwise normal cadaveric feet while measuring bony motion as well as force beneath the foot. The dorsal tarsometatarsal and the dorsal intercuneiform ligaments were attenuated and three muscle imbalances, each similar to imbalances believed to cause the pes cavus deformity, were applied while bony motion and plantar forces were measured.

Only one of the muscle imbalances (overpull of the Achilles tendon, tibialis anterior, tibialis posterior, flexor hallucis longus and flexor digitorum longus) was successful at consistently generating the changes seen in pes cavus feet. This imbalance led to statistically significant changes including hindfoot inversion, talar dorsiflexion, medial midfoot plantar flexion and inversion, forefoot plantar flexion and adduction and an increase in force on the lateral mid- and forefoot.

We have created a cadaveric model that approximates the general changes of the pes cavus deformity compared to normal feet. These changes mirror the general patterns of deformity produced by several disease mechanisms.

Future work will entail increasing the severity of the model and exploring various pes cavus treatment strategies.