The plantar fascia, more accurately known as the plantar aponeurosis, is a thick band of connective tissue that runs on the plantar aspect of the foot from the calcaneus (the heel bone) to the proximal phalanges of each digit. As it approaches the digits, it branches out, sending a projection to each toe.
The primary function of the plantar aponeurosis is to maintain the arch of the foot as pressure is translated to the foot. The bones of the foot form a natural arch that assists in balance and mobility. Without the plantar aponeurosis, this arch would flatten out against the ground as weight is applied to the foot. Another role of the plantar aponeurosis is to translate the contraction of the calf muscles into effective plantarflexion. The calf muscles attach to the calcaneus via the Achilles tendon. The plantar fascia in turn attaches to the Achilles tendon at the heel, thus forming a continuous connective tissue band from the calves to the toes.
Anatomical view of the plantar aponeurosis. The red lines indicate the outline of an intact plantar fascia (it has been cut in this image)
The mechanism of plantar fasciitis is poorly understood. What we do know is that plantar fasciitis appears due to overuse of the plantar fascia. Overuse can occur in many ways. Athletes who run and jump will put the aponeurosis through its paces. For the non-athlete population, obesity is a major risk factor for plantar fasciitis, since all that extra body weight forces the aponeurosis to maintain excessive tension on the bones of the foot to prevent the arch from collapsing.
Plantar fasciitis is the most common cause of heel pain in all populations. This pain is due to damage or degeneration of the plantar fascia where it inserts onto the calcaneus. While is most intense under the heel, pain can be experienced all along the aponeurosis, decreasing in intensity from medial to lateral. Tears of the plantar fascia can occur following excessive dorsiflexion.
Treatment for both plantar fasciitis and plantar fascia tears is generally conservative. The foot is immobilized to prevent dorsiflexion and plantarflexion. The plantar fascia likely will heal on its own following rest and brief physical therapy. If the injury does not respond to conservative treatment, steroid injections for inflammation and ultimately surgery remain viable options.
With that said, Merry Christmas and a Happy New Year to all! Go Irish, beat Tigers.