Plantar Fasciitis is a difficult diagnosis to treat in some cases. Individuals may have symptoms for a couple weeks to many many years. One of the many reasons that this diagnosis is difficult to treat is due to a limited understanding of the root cause. It is essential to differentiate between symptoms due to damage to the plantar fascia, harm to a muscle or tendon in the foot, bruising of the heel bone, or irritation of the nerve or nerves.
Once you make that discrimination and you are leaning heavily toward plantar fasciitis you may start to delve deeper into its cause. Is it caused by a bone spur at the bottom of the heel or abnormal kinematics of the foot? Usually an x-ray can help to find a bone spur in the heel that may be causing damage to the fascia. After you rule out a spur you can focus on the mechanics of the foot.
There is some argument in the literature about the biomechanical effects the foot and ankle play into stressing the plantar fascia. I reviewed an article that compared the kinematics of the foot and ankle in people with and without plantar fasciitis. They showed that people with plantar fasciitis had greater total rearfoot eversion, greater forefoot plantar flexion at initial contact, greater total sagittal plane forefoot motion, greater maximum first toe dorsiflexion (this places increased strain on the plantar fascia due to the Windlass Mechanism), and decreased vertical Ground Reaction Force during propulsion. The researchers stated that the decrease in Ground Reaction Force and the increase in forefoot plantar flexion are compensatory mechanisms due to pain. (An increase in arch angle of ~1 degree can cause an increase in plantar fascia tension from 0.4 to 0.7 of body weight during stance) They believe that the increased rearfoot eversion and first toe dorsiflexion are more of a factor in plantar fasciitis. Focusing on these two factors may help people relieve their symptoms. But what can be done to improve these abnormalities? Towel Curls with the toes are great for strengthening to toes (mainly the first toe) but is that enough to strengthen the toes for walking or is there a more aggressive way to strengthen functionally? Also, can you combine that with improving the strength of the muscles that invert the foot? My thought would be to complete a toe raise on the edge of a step or leg press machine with the heel all the way down and only raising to neutral while focusing on inverting the foot. Make sure to not go past neutral as to not stress the plantar fascia and keep the knee slightly bent to avoid using the gastrocnemius muscle. Complete barefoot to help engage the toes for stability.
The image below is an example of the exercise. The only corrections I would suggest is standing closer to the edge of the step as to not have so much of the ball of the foot on the step and work on toe strengthening. Also, make sure to keep the knee bent throughout the exercise.
(Click the link below for access to the article)
Purpose: To determine whether healthy and plantar fasciitis feet are different with respect to multi-segment foot kinematics (rearfoot motion, medial forefoot motion, first metatarsal phalangeal joint motion) and Ground Reaction Force.
Methods: The researchers studied 44 subjects (22 healthy individuals and 22 with plantar fasciitis). Inclusion criteria for the experimental group consisted of being 30-60 years old, heel pain with palpation at insertion point, persistent symptoms for at least 3 months, and 5 episodes of first-step pain in last month. Exclusion criteria consisted of a history of local steroid injection within last 2 months, arthritis, local traumatic injury, a body mass index greater than 35, and a high foot arch. The researchers placed markers on the foot and lower leg and assessed the movement of those points while the subjects walked at a predetermined speed.
Results: Both groups did not differ in age, height, body mass, standing arch ratio, foot posture index, and 6-meter preferred walking speed.
- Rearfoot: There were significantly greater total rearfoot eversion with the plantar fasciitis group which means greater overall pronation motion. They found that both groups had the same movement pattern during gait; inversion at initial contact, eversion at mid-stance, and inversion at push-off.
- Medial Forefoot: Significantly greater total plantar-dorsiflexion motion with the medial forefoot being in a more plantar flexed position at initial contact.
- First Metatarsal Phalangeal Joint (First Toe): Significantly greater maximum dorsiflexion/extension of this joint in late stance.
- Ground Reaction Force: Significantly less peak vertical forces at propulsion with walking speed controlled.
Limitations: This was a case-controlled study and is retrospective by nature so it does not show that these deviations in the foot actually cause plantar fasciitis. Also, the researchers mentioned that the skin markers may be able to move during walking due to gliding of tissues on bony prominences but was able to stay relatively stable overall.