Design and validation of a dynamic stretch splint for plantar fasciitis

Background: Plantar fascia stretch plays an important role in the treatment of plantar fasciitis. Existing stretch splints mostly provide stretch to Achilles tendon but not to the plantar fascia. The ones that do are inefficient and uncomfortable because of their static nature. In this paper a dynamic stretch splint featured both ankle and metatarsophalangeal joint stretch was designed and developed. This splint should provide continuous stable stretch and be able to monitor the load of stretch during clinical application. To validate the design, twenty volunteers were tested under two stretch conditions, static and dynamic. Forces generated between the splint and the foot across 30-min testing were registered. Level of comfort and joint range-of-motion changes after splint application were evaluated. Statistical results demonstrated significant differences in load of stretch and in level of comfort between the static and dynamic conditions, but not in joint range-of-motion. The findings indicated that the designed splint could provide a continuous load of stretch, eliminate discomfort and increase user compliance comparing to static splint. Its long term effect onto joint angle improvement needs further investigation. Potentially it may be used on subjects with plantar fasciitis, and subjects with foot problems accompanying plantar tissue contracture.