Jack Test
What is the "Jack Test" used for?
- Jack Test demonstrates hindfoot/ subtalar flexibility in a flexible flatfoot and is based on the principle of “windlass” action of the plantar fascia.
How to perform the "Jack Test"?
- Jack Test is performed by dorsiflexing the big toe and looking for the appearance of a medial arch. Dorsiflexion of the big toe pulls the plantar fascia distally under the pulley of the head of the first metatarsal.
- The big toe can only fully dorsiflex if the calcaneus is pulled distally toward the metatarsal heads, thereby shortening the foot, elevating the longitudinal arch, and inverting the subtalar joint.
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