What is plantar fasciitis?
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 present 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)
How did I get it?
Like most cumulative trauma disorders, the etiology of plantar fasciitis is multi-factoral. (21) 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) 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)
Tightness or weakness in the gastroc and soleus directly contribute to plantar fasciitis by increasing tensile strain on the plantar fascia. (25-27) 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)
What are the risk factors?
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)
Patients may be predisposed by occupations or activities that involve prolonged ambulation including: teachers, construction workers, cooks, nurses, distance runners, etc. 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)
What are the symptoms?
The most common presenting complaint of plantar fasciitis is a sharp pain with the first couple of steps in the morning or following any period of prolonged inactivity. (16,25) Symptoms are often noted during the push off phase when the band is at peak tension. (32) Symptoms are amplified by prolonged weight bearing, especially when compounded by inadequate foot support or walking barefoot. (25) Walking upstairs and sprinting or forefoot running tends to exacerbate symptoms by increasing plantar fascia strain. Patients report relief when unloading the foot by sitting or lying down. Symptomatic episodes are more frequent following periods of inactivity late in the day.
Will I need an x-ray?
Radiographs are typically not required for the diagnosis of plantar fasciitis. (51) Radiographs may, however, be useful in differentiating plantar fasciitis from other diagnoses, including neoplasm or fracture. Calcaneal stress fracture may appear on standard radiography as a radiopaque band traversing the trabecular pattern in the posterior calcaneus. Plain film radiographs commonly expose plantar calcaneal enthesopathy (heel spurs).. Studies demonstrate no correlation between spur size and the patient’s subjective complaints. (52) Calcaneal enthesophytes are considered coincidental and irrelevant radiographic findings. (53) They are a sequelae rather than a cause of the process. (54,55) Spurs are thought to develop when long-standing tension creates a traction apophysitis, via Wolf’s Law. The presence of a heel spur suggests abnormal stress in the region for at least six months. (56) Heel spurs are present in approximately 50% of symptomatic patients and 15-20% of asymptomatic patients. (54,57) Studies now suggest that heel spurs develop at the origin of the flexor digitorum brevis muscle as opposed to the plantar fascia attachment. (58)
Bone scans may be useful to rule out calcaneal stress fracture or neoplasm, although will not differentiate between the two. Advanced imaging, including MRI, may be appropriate for recalcitrant cases or to rule out differential diagnostic considerations, including Baxter’s neuritis. Sonographic studies demonstrate that while the average plantar fascia is approximately 2 mm thick, patients with plantar fasciitis symptoms demonstrate degenerative thickening of 4 mm or greater. (59) Diagnostic ultrasound evidence of decreasing plantar fascia thickness is associated with improvement. (60)
Will it get better on its own?
Eighty to ninety percent of plantar fasciitis patients foregoing treatment will report resolution of their complaints within 18 months. Conservative treatment, including manual therapy, stretching, myofascial release, exercise, orthotics, physical therapy modalities, and night splints may improve results. (61-63) The best treatment outcomes are achieved by combining multiple techniques- particularly mobilization and exercise. (63,97)
How is it treated?
Patients may need to temporarily limit activities that exacerbate symptoms, including jumping, running, and sprinting. Once patients find a tolerable level of activity, they should not increase their training intensity by more than 10% per week. (64) Runners should avoid running hills, and toe or forefoot runners may need to temporarily alter their running form. Runners may benefit by reducing stride length and increasing cadence. (36) Running shoes lose half of their shock absorption capacity after 300-500 miles and should be replaced within that range. (65,88,89) Safer alternatives to running include swimming, bicycling, and elliptical machines. (66)
Patients who hyperpronate and those with fallen arches will benefit from arch supports or orthotics. (67) The use of a Tensoplast wrap or commercial elastic wrap (PSC fabrifoam) will help support fallen arches. Low dye taping is effective in limiting pronation. (68) A medial heel wedge forces the foot into a varus posture and significantly reduces plantar fascia strain. (69) Patients with true hypersensitivity to pressure may benefit from a viscoelastic heel cup or small cushion donut over the medial calcaneal tubercle. (70) The use of elastic therapeutic tape has been proposed for the treatment of plantar fasciitis.
Immobilizing tissue in a lengthened state speeds recovery. (71) Chronic plantar fasciitis patients may benefit from using a boot or night splint (Strassburg sock), which limits passive plantar flexion and allows the plantar fascia to “heal” in a lengthened state. (92,93) Patients should be counseled on proper shoe wear. Patients with low arches may benefit from “motion control” shoes. Runners with average arches should choose “neutral” or “stability” shoes. (72) Patients with high arches may benefit from a “cushioned” shoe. (73)
Since most chronic cases of plantar fasciits do not show histologic evidence of inflammation, the benefit of “anti-inflammatory” modalities is questionable. (74) Some patients report at least palliative relief by using NSAIDs, ice, and modalities. Low-level laser therapy may be useful for the treatment of chronic plantar fasciitis. (75)
How can chiropractic help?
Ankle joint mobilization and manipulation can help restore normal motion, particularly dorsiflexion. (76,77,90) The addition of gastroc/ soleus and plantar fascia trigger point massage and soft tissue manipulation to traditional treatment programs produces superior short-term outcomes. (62) Myofascial release procedures, including transverse friction massage and IASTM are effective tools that may stimulate fibroblast proliferation and plantar fascia regeneration. (79,80,95) IASTM may be performed in a fanning fashion over the length of the plantar fascia in a strumming fashion near the medial calcaneal origin.
Stretching exercises are appropriate for the gastroc, soleus, hamstring, and plantar fascia. (81,91) The plantar fascia may be effectively stretched by sitting in a Figure 4 position, and fully dorsiflexing the great toe for 10 seconds repetitively throughout the day. Routinely stretching the plantar fascia in this fashion is associated with significantly improved outcomes. (81) Plantar fascia mobilization may be performed at home by rolling a golf ball or frozen water bottle beneath the plantar fascia. The use of a Prostretch may assist in stretching and mobilizing the plantar flexors.
Strengthening exercises are appropriate for the gastroc, soleus, posterior tibialis, and intrinsic muscles of the foot. (82) Examples include marble and towel gripping exercises. Strengthening exercises for the posterior tibialis should be implemented to help arch support. Strengthening of the flexor digitorum brevis is an important component of treatment and may be accomplished by performing toe flexion with an exercise band. (36) Eccentric heel raises with the great toe positioned in passive dorsiflexion (i.e. great toe propped up with a towel) have shown benefit for plantar fasciitis patients. (98)
Nearly two-thirds of foot and ankle orthopedic specialists prefer stretching and manual therapy over anti-inflammatories or corticoid steroid injections for chronic plantar fasciitis patients. (83) Medical management of recalcitrant plantar fasciitis includes extracorporeal shock-wave therapy (ESWT), cortisone injections, and surgery. ESWT has shown to help some patients. (63,85) ESWT (originally developed as lithotripsy) is thought to break up calcific deposits and stimulate fibro blast activity to encourage healing. Corticoid steroids may provide an anti-inflammatory effect in cases where inflammation is present but carry the risk of spontaneous plantar fascia rupture or damage to the heel pad. (62,87) Surgical management includes fasciotomy.
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