Effect of cutting the plantar fascia on mechanical properties of the foot.

A biomechanical model was used to calculate the loadbearing characteristics of the plantar fascia and to determine the effect of cutting the plantar fascia on the stiffness of the foot. With a load of 683 N applied to the foot, the model predicted a 17% increase in vertical displacement and a 15% increase in horizontal elongation when the plantar fascia was cut, compared with the corresponding value when the plantar fascia was intact. Plantar fasciotomy, although clinically satisfactory in cases of recalcitrant heel pain, decreases the stiffness of the foot and creates a less rigid and more deformable arch. The biomechanical model described can help to evaluate the possible outcome of such a procedure.