Point-Counterpoint: Recalcitrant Plantar Fasciitis: Is Fasciotomy Ever Necessary?
Many surgeons, including myself, have noted very encouraging results with partial plantar fasciotomy.12,13 However, before one contemplates cutting the central component of the plantar aponeurosis in an attempt to relieve a patient’s chronic plantar heel pain, the podiatric surgeon must first carefully consider the multiple biomechanical functions of the central component of the plantar aponeurosis that may be negatively altered or completely eliminated by cutting this vital structure of the plantar foot.
Hicks first described the important mechanical functions of the plantar aponeurosis, which included his classic concept of the windlass effect.14 He noted that dorsiflexion of the hallux produced longitudinal arch raising, subtalar joint supination and external rotation of the tibia in weightbearing cadaver limbs, which was completely eliminated with surgical transection of the plantar fascia. Carlson and colleagues found that increasing tension within the Achilles tendon caused an increase in plantar fascia tension at four different angles of MPJ dorsiflexion.8
Erdemir and co-workers found that tension within the plantar fascia was directly proportional to Achilles tendon tension in cadavers in a dynamic gait simulator and that plantar fascia tension peaked at heel-off at 0.96 times body weight.9 Cadaver studies have shown that plantar fasciotomy decreases arch height, lengthens the arch and dorsiflexes the first metatarsal.15,16
Other important biomechanical functions of the central component of the plantar aponeurosis include: facilitating normal resupination of the subtalar joint during propulsion; assisting the deep posterior compartment muscles at resisting pronation; assisting the plantar intrinsic muscles at resisting longitudinal arch flattening; and reducing the tension strain within the plantar ligaments.3,17,18 The central component of the plantar aponeurosis also helps reduce the interosseous compression forces within the dorsal joints of the midfoot and helps prevent excessive bending strains on the metatarsals during weightbearing activities.3,19,20
The central component of the plantar aponeurosis passively maintains digital purchase force on the ground by increasing the digital plantarflexion moment. This in turn helps reduce metatarsal head plantar pressures.3,14,19 Lastly, the central component of the plantar aponeurosis, along with the other plantar ligaments, help to store sufficient strain energy with the longitudinal arch. This helps make running activities more energy efficient.21
Even though plantar fasciotomy can be a useful surgical alternative to treat the pain and disability from chronic plantar fasciitis, the cutting of this important supporting structure of the plantar longitudinal arch, the central component of the plantar aponeurosis, may lead to negative biomechanical consequences for the patient.
Therefore, before performing this surgical procedure, podiatric surgeons must carefully weigh its positive benefits along with its possible negative biomechanical alterations in foot structure and function for their patients with chronic plantar fasciitis.
Dr. Kirby is an Adjunct Associate Professor within the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt University in Oakland, Calif. He is in private practice in Sacramento, Calif.