What is Plantar Fasciitis?
Plantar Fasciitis (fash-e-i-tis) is one of the most common causes of heel pain, accounting for almost 15% of all foot-related complaints (Lutter, 1997), affecting the middle aged (40-50). More women than men are affected by this condition, with about 65% reported to be overweight. It is understood to be an overuse injury to the plantar fascia and the surrounding structures, which over time cause small tears and inflammation of the tissues. Those with Plantar Fasciitis describe that is worse in the morning and after seated rest upon walking.
The condition involves inflammation of the plantar fascia (a tough fibrous band of tissue that runs along the sole of the foot with attachments to the heel bone (calcaneous) and to the base of the toes. The plantar fascia provides support to the arch of the foot and has an important role in normal walking. Tension or stress in the plantar fascia increases when weight is placed on the foot (standing) and as one pushes off on the ball of the foot and toes (walking or running).
Inflammation and pain start in the fascia either as a result of an increase in activity level (starting a walking or running program), or with the normal aging process. With aging, the fascia loses some of its normal elasticity and may become irritated with routine activities. Less commonly, Plantar Fasciitis can develop in association with medical conditions such as lupus or rheumatoid arthritis.
Anatomy of the Plantar Fascia
The plantar fascia is a structure that runs from the front of the heel bone (calcaneous) to the ball of the foot. The plantar fascia is made up of connective tissue arranged in sheets, and arises from the posteromedial portion of the calcaneal tuberosity on its inferior aspect. It consists of the central band being the strongest and thickest which passes beneath the metatarsal heads and connects into the flexor sheath, volar plate (sole), and the base of the proximal phalanx of the hallux (toe). It also inserts into the plantar skin just distal to the first metatarsal head. This dense strip of tissue helps to support the long arch of the foot, by acting similar to the string on a bow.
When the foot is on the ground a large amount of force (weight of our body) is on the plantar fascia. This can lead to stress on the plantar fascia where it attaches to the calcaneous (heel). Small tears of the tendon may result and are repaired by the body. As the healing process repeats itself over and over, a bone spur forms as the body’s response to try and firmly attach the fascia to the bone. This appears on an x-ray of the foot as a heel spur.
Function of the Plantar Fascia
The plantar fascia works during the gait (walking) cycle when the heel on one side has lifted, but the heel on the opposite foot has not yet touched the ground. During this action, the foot will experience a higher reaction force than at any other time in the gait cycle. As the heel lifts, the plantar fascia will start to tighten. The higher the heel lifts, the tighter the plantar fascia will get.
As the heel lifts, the plantar fascia will tighten and pull the heel toward the forefoot. This will heighten the arch and resist the increasing body weight from flattening the foot.
With premature heel lift from tight calf muscles, the plantar fascia will not properly raise the arch and resist the body weight from flattening the foot. This elongation will put tension on the fascia, at its’ attachment. Over time, symptoms of overuse will occur.