Aetiology
Plantar fasciitis has traditionally been considered an overuse injury caused by repetitive microtrauma and damage to the plantar fascia, although the true aetiology of the condition is unknown. Several factors have been associated with its development, including biomechanical abnormalities (e.g., equinus, pes planus, and pes cavus), increased body mass index, athletic and sedentary lifestyles, and prolonged standing on hard surfaces such as concrete.[3] Most of these suggestions are based on case series and have not been shown to be directly associated.[4][12][13][14] Multiple other extrinsic risk factors have been proposed, including wearing improper or excessively worn shoes, running on unyielding surfaces and other training errors, increases or changes in activity, and spending most of the workday on the feet or walking.[3]
Pathophysiology
Biopsy of the plantar fascia in patients with fasciitis has found microtears, chondroid metaplasia, matrix calcification, angiogenesis, and several patterns of collagen degeneration and repair.[1] Some researchers have proposed a process of degenerative fasciosis without inflammation, demonstrating myxoid degeneration, fibrocartilage fibre fragmentation, and vascularisation at the enthesis on histological specimens from heel spur surgery.[15] Some have proposed a chronic inflammatory process.[1]
Classification
Association with trauma
Pain subsequent to acute traumatic event: patient may relate that pain in heel began abruptly after physical activity or after a traumatic incident (e.g., falling off a ladder).
No known preceding acute trauma: patient may not be able to recall any preceding trauma to the foot; pain likely to have a repetitive microtraumatic aetiology.
Duration of symptoms
The American College of Foot and Ankle Surgeons recommends categorising patients by duration of symptoms in order to allow selection of treatments that will have the greatest effect within each stage of plantar fasciitis. They define the 3 phases of plantar fasciitis as follows:[3]
Acute: symptoms present for up to 6 weeks
Subacute: symptoms present for 6 to 12 weeks
Chronic: symptoms present for >3 months
A subdivision of chronic is refractory/recalcitrant. Refractory plantar fasciitis is best defined as chronic plantar fasciitis that has not improved with appropriate intervention for >6 months and is much more difficult to successfully treat.
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