Consequences of partial and total plantar fascia release: a finite element study.

BACKGROUND: Plantar fasciotomy, a common operative procedure to relieve chronic heel pain, has been suggested to decrease foot arch stability. A systematic evaluation of the biomechanical consequences of partial or total plantar fascia release is essential to the understanding of the biomechanical rationale behind these operative procedures.

METHODS: A geometrical detailed three-dimensional (3-D) finite element (FE) model of the human foot and ankle, incorporating geometrical and contact nonlinearities, was constructed by 3-D reconstruction of MR images. Partial and complete plantar fascia releases were simulated to evaluate the corresponding biomechanical effects on load distribution of the bony, ligamentous, and encapsulated soft-tissue structures.

RESULTS: Partial and total plantar fascia release may decrease arch height but did not necessarily cause total collapse of the foot arch even with additional dissection of the long plantar ligament. Operative release of the plantar fascia was compromised by increased strains of the plantar ligaments and intensified stress in the midfoot and metatarsal bones. Load redistribution among the centralized metatarsal bones and focal stress relief at the calcaneal insertion were predicted with different types of fasciotomy.

CONCLUSIONS: The FE model suggested that plantar fascia release may provide relief of focal stress and therefore could relieve associated heel pain. However, these operative procedures may pose a risk to arch stability and clinically may produce dorsolateral midfoot pain. The initial strategy for treating plantar fasciitis should be nonoperative. If surgery is necessary, partial release of less than 40% of the fascia is recommended to minimize the effect on arch instability and maintain normal foot biomechanics.