A Novel Approach to Plantar Fasciitis in the Aging Population

Twenty five percent of older adults experience foot pain. Plantar fasciitis, a repetitive strain injury, is one of the most common causes of foot pain in this population. Ten percent of aging adults experience plantar fasciitis with 50% of the cases being disabling. Foot pain can lead to other problems such as reduced mobility, depression and prescription medication use, leading to a reduced quality of life. Foot pain has been related to foot weakness, reduced static and dynamic balance, and reduced walking speed in aging adults.

The standard of care for plantar fasciitis is to brace the arch with foot orthoses and supportive shoes, thereby reducing the strain on the plantar fascia. However, arch support has been shown to be an ineffective long-term strategy for reducing foot pain, as well as leading to intrinsic foot muscle atrophy. As plantar fasciitis is associated with this atrophy, treating it with chronic arch support only increases the risk for recurrence. In fact, there is a 50% recurrence rate and a 45.6% risk of having plantar fasciitis 10 years after the onset of symptoms, and this risk increases with age.

Minimal shoes are designed to allow the foot to function naturally, as if barefoot, which have already been successfully implemented in older adults for the treatment of knee osteoarthritis. Minimal shoes are highly flexible and lack the support of conventional footwear. This places a greater demand on the foot muscles, which promotes strengthening. Indeed, studies of gradual transitioning to walking in minimal shoes have demonstrated significant increases in intrinsic foot muscle size and strength. Stronger foot intrinsic foot muscles have been shown to reduce the strain on the plantar fascia with each step, thereby reducing the risk of developing plantar fasciitis. This is especially important in the older population who develop muscle weakness as they age.

The overall objective of this study is to improve treatment interventions for plantar fasciitis in aging adults. The central hypothesis of this research is that strong intrinsic foot muscles will reduce the strain on the plantar fascia. This, in turn will result in resolution of pain, with less recurrence of plantar fasciitis than the standard of care. The investigators will test this hypothesis by comparing an intervention of stretching, foot orthoses and supportive shoes to one of foot stretching, strengthening and transition to minimal footwear. Training the foot of a patient with plantar fasciitis to function with less support is a significant paradigm shift from interventions aimed at passively supporting the foot. However, the investigators hypothesize that the dynamic stability of the foot muscles will be more effective than a static foot orthosis, that has been shown to promote foot weakening. The investigators will assess outcomes of foot pain, functional activities, and muscle strength, size and function at the 3- and 6-month follow-up, and the incidence of recurrence of plantar fasciitis at the 12 month time point.