The plantar fascia is a dense, fibrous band serving as a biomechanical stabilizer as well as a protector to the vulnerable neurovascular structures on the plantar aspect of the foot. The diagnosis “plantar fasciitis” encompasses disorders ranging from acute inflammation to chronic fibrotic degeneration, usually involving the calcaneal attachment. (1,2) Plantar fasciitis most commonly affects the medial portion of the band. (2)
The band’s proximal origin is the medial calcaneal tubercle, and its distal attachments are all five toes. The band functions, via the “windlass mechanism” to stabilize the foot during gait- i.e. at heel strike, the plantar fascia is slack to allow the foot to accommodate uneven surfaces. As the heel lifts and forefoot dorsiflexes toward toe off, the distal plantar fascia “winds” up and around the first MTP joint pulling the plantar fascia taut, shortening the distance between the heel and forefoot, raising the arch– creating a stiffer lever for propulsion. (3)
Although the term, “plantar fasciitis” implies inflammation, more recent studies suggest that plantar fascia pain results from a non-inflammatory, degenerative process. (4-12) Initial insults may generate an acute inflammatory reaction, but repetitive chronic overload results in a breakdown of the inflammatory process and a disorganized healing process that fails to regenerate “normal” tissue.
Plantar fasciitis is the most common cause of plantar heel pain, affecting approximately 10% of the population. (14-18) The condition is responsible for one quarter of all foot injuries. (115) Plantar fasciitis presents bilaterally in 20-30% of those affected. (19) The condition is common in young runners and middle-aged women, but the majority of plantar fascia patients are over the age of 40. (16-18)
Like most cumulative trauma disorders, the etiology of plantar fasciitis is multi-factoral. (21) Significantly higher total cholesterol levels were found in plantar fasciitis patients over the age of 45 in comparison with other orthopedic outpatients. (144) Problems typically arise when repetitive eccentric strain exceeds the tissues threshold for injury. Certain factors may increase the likelihood of developing the disorder. The leading biomechanical cause for plantar fasciitis is pes planus (fallen arch) which increases tension on the plantar fascia, leading to repetitive micro trauma at the band’s vulnerable attachment on the medial calcaneus. (22) One study suggested that spring ligament strain & failure precedes plantar fascitis regardless of foot shape. (133) Patients with pes cavus are likewise predisposed since a cavus foot is relatively immobile, and forces that would generally be dissipated by bony structures are now absorbed by the plantar fascia. (16,25) Halux valgus affects the windlass mechanism and is another known risk factor for plantar fasciitis. (111)
Tightness or weakness in the gastroc and soleus directly contribute to plantar fasciitis by increasing tensile strain on the plantar fascia. (25-27,123) Gastroc and soleus hypertonicity limits dorsiflexion – meaning the plantar fascia must accommodate for this lost motion. (28) Gastroc and soleus weakness limits propulsion and increases loads on the plantar fascia and the intrinsic muscles of the foot. (28) Gastroc tightness directly correlates to the severity of plantar fasciitis symptoms. (123, 130)
Patients with plantar fasciitis are almost 9 times more likely to demonstrate hamstring hypertonicity. (29) Hamstring tightness may induce prolonged forefoot loading and increase strain to the plantar fascia. (30) Rapid weight gain and obesity are also recognized contributors to plantar fasciitis. (17,25) Patients with BMI’s greater than 35 are approximately 2.5 times more likely to experience plantar fasciitis as compared to those with BMI’s less than 35. (29,117) Age and body mass index were also strongly correlated with concurrent calcaneal spur size and pain in patients with plantar fasciitis. (150)
Patients may be predisposed by occupations or activities that involve prolonged ambulation including: teachers, construction workers, cooks, nurses, distance runners, etc. Footwear plays an important role in causing plantar fasciitis as the majority of the diagnosed cases wear inappropriate shoes with minimal heel height, thin sole, and hard insole without any built-in arch support. (154) Runners average 1200 steps per mile at a 6-minute per mile pace, and walkers average 2300 steps at a 20-minute/mile pace. The plantar fascia must absorb up to seven times body weight during the push off phase of running and biomechanical deficits are quickly amplified. Patients often present following an increase in training demand or change in running surface- i.e. concrete. (25)
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What we do in our office to help this condition:
1. Perform a detailed exam, assessing the alignment of the spine, pelvis, hips, knees, ankles, and small bones of the foot. Improper alignment in any of these areas may be detrimentally affecting the function of the plantar fascia, and compromising its ability to function normally.
2. As indicated, adjust areas of subluxations (misalignments), restoring proper alignment and nerve system function, which facilitates healing. It is common to find subluxated bones in the feet when someone is experiencing plantar fasciitis.
3. Perform laser therapy which penetrates to the cellular level of the soft tissues of the plantar fascia. This promotes better oxygen and nutrients to the tissue, which can relieve pain and facilitate the healing process.
4. Conduct an electronic foot scan to see if the integrity of the foot’s arches have been compromised. If so, custom arch supports (orthotics) would be of benefit and can be prescribed.
5. Prescribe stretches and exercises in conjunction with chiropractic care to strengthen the soft tissues of the plantar fascia.