Plantar fasciitis is the most common foot condition treated by healthcare providers. It is the most common diagnosis for foot running injuries and making up 8% of all running injuries (1). The clinical course for most patients is positive with 80% reporting resolution of symptoms at the 12 month follow up (1). Most patients make significant improvements in 1-3 months as reported above with various treatment methods.
The specific cause of plantar fasciitis is poorly understood. It is considered an overuse injury that has multiple causes. Some causes are external: training errors, improper shoes, excessively worn shoes, & running on hard surfaces (2). Some causes are internal: if you have limited ankle motion (dorsiflexion), weak plantarflexors (calf), tight calf muscles, malalignment of the lower leg, or if you were born with a foot structure that requires you to compensate and pronate quicker and through more range (excessive pronation) in order to absorb the impact when your foot hits the ground running. One contributing factor to developing plantar fasciitis seems to be foot structure; between 81 and 86% of individuals with plantar fasciitis have been found on examination to have excessive pronation (2). Those individuals that have excessive pronation increase the tension placed on the plantar fascia. Pronation is usually identified as someone having a flat foot or low arch. However, those that have a stiff foot (high arch) have also been implicated to have plantar fasciitis because of this foot type’s inability to effectively absorb the forces during weight bearing activities (2). Opposite foot types call for different treatment approaches but yet the same problem: plantar fasciitis.
Main Risk Factor: Decreased Range of Motion
Another study examined 50 patients and the most important risk factor associated with developing plantar fasciitis was reduced ankle dorsiflexion; the risk of developing plantar fasciitis increased as the motion of ankle dorsiflexion decreased (3). Other independent factors that increased the risk of developing plantar fasciitis included: obesity and prolonged standing/weight bearing during the work day (3).
Decreased range of motion creates stiffness and changes the way the ankle and foot mechanics work during running. The big toe (first metatarsophalangeal joint or 1st MTP) is a very important joint when considering push off for walking and running. It is the last joint to have contact as you push off. One study evaluated the motion of the 1st MTP joint in a group of runners that had plantar fasciitis compared to runners without plantar fasciitis (4). The running group with plantar fasciitis had statistically significantly decreased 1st MTP extension motion (bringing your big toe up – or as when you push off during running/walking), decreased passive extension (you move it with your hands), and decreased passive flexion (you bend or curl the big toe with your hand) (4). This joint is important for pushing off and adequate motion is needed to perform walking and running. Therefore, the big toe joint should be evaluated as part of every standard runner physical therapy evaluation and treated to increase range of motion if stiff.
References:
1. McPoil TG, Cornwall MW, Wukich DK, Irrgang JJ, Godges JJ, Martin RL. Heel pain plantar fasciitis. Orthop Sports Phys Ther. 2008;38(4):A1-A18.
2. Cornwall MW, McPoil TG. Plantar Fasciitis: Etiology and Treatment. J Orthop Sports Phys Ther. 1999;29(12):756-760.
3. Riddle DL, Pulisic M, Pidcoe P, Johnson RE. Risk factors for Plantar fasciitis:a matched case-control study. J Bone Joint Surg Am. 2003;85-A:872-877.
4. Creighton D, Olson VL. Evaluation of range of motion of the first metatarsophalangeal joint in runners with plantar fasciitis. J Orthop Sports Phys Ther 1987;8(7):357-361.
