The Journal of the American Osteopathic Association, December 2014, Vol 114, Number 12, 900-906
The plantar fascia spans from the medial aspect of the calcaneus distally to the base of each proximal phalanx. In plantar fasciitis the most medial aspect of the plantar fascia that attaches to the first proximal phalanx is what typically is degenerative with histological findings of fibrosis, collagen necrosis, chondroid metaplasia, and calcification. These histological findings are actually more consistent with a chronic fasciosis rather than an acute fasciitis.
The medial aspect of the plantar fascia is most susceptible because of the “windlass mechanism” which occurs when we are walking and transitioning from flat foot to toe off during gait. As we move from flat foot to toe off the medial plantar fascia becomes tense and this tension elevates and reinforces the medial longitudinal arch of the foot. When we propel ourselves forward during toe off it is the tension in the medial plantar fascia that provides the rigid lever and energy for our propulsion. This mechanism can set us up for injury with overuse, high arches (cavus) and flat arches (planus). There is a diversity of people who are susceptible to plantar faciitis: military or others who have to stand or march for prolonged times, marathon runners; but also obese or sedentary people. Peak incidence occurs between 45 and 64 years of age and it is more common in women.
The telltale findings on physical exam include tenderness to deep palpation on the plantar medial aspect of the heel and pain with passive dorsiflexion of the ankle and toes. Either a high or flat medial arch may also be noted. Typical somatic dysfunctions you should evaluate for include posterior fibular head, navicular and/or cuboid restrictions, as well as talus and calcaneal restrictions. All somatic dysfunction should be evaluated and treated. If you are not familiar with the typical foot somatic dysfunctions and how to treat them, then consider purchasing my CME course for Osteopathic Manipulative Medicine for the foot on my website OMMEducation.com. In this course I cover the functional anatomy of the four arches of the foot and how to treat the typical somatic dysfunctions found in these arches.
85-90% of patients with plantar fasciitis can be treated successfully with conservative treatment which may include: OMM, stretching, range of motion, orthoses, posterior tension night splints, ultrasound, massage, extracorporeal shock wave therapy, and NSAID’s. The use of shoe inserts in combination with stretching has shown better short term results than stretching alone and a RCT that compared over the counter shoe inserts to customized inserts found no significant difference between the two at 12 month follow-up.
Interestingly, a randomized double-blinded trial that added 1 application of high energy extracorporeal shock wave therapy to standard therapies showed a statistically significant improvement in symptoms at 3 months compared to standard therapies without ESWT.
When it comes to invasive therapies corticosteroid injection should be considered with caution due to an unfavorable risk to benefit ratio. Corticosteroids showed improved symptoms at one month follow-up, but not at 6 month follow-up. This injection also has risk of skin and fat pad atrophy, infection and 10% incidence of plantar fascia rupture. The article does not discuss any studies related to prolotherapy or platelet rich plasma injections. Surgery, which involves a partial or complete plantar fasciotomy, should only be considered as a last resort after 6 to 12 months of failed conservative multimodal therapies. This may place the foot at risk for detrimental effects on other ligamentous and boney structures of the foot; but surgery has shown a substantial decrease in symptoms.
The listed differential diagnoses to consider in someone with chronic heel and plantar pain that is not responding to treatments are:
- Calcaneal Stress Fracture
- Subtalar or Talonavicular arthritis
- Fat Pad Atrophy
- Insertional Achilles Tendonitis
- Retrocalcaneal Bursitis
- Tarsal Tunnel Syndrome
- S1 Radiculopathy
- Peripheral Neuropathy
- Lateral Plantar Nerve or Medial Calcaneal Nerve Entrapment