For normal first metatarsophalangeal joint function during the propulsive phase of gait, the following is needed:
the subtalar joint should be supinating, the midtarsal joint should be stable and the windlass mechanism is being established
the peroneus longus muscle is providing a plantar and lateral force to the first ray
the first metatarsal must be able to plantarflex below the level of the second (hallux dorsiflexion can not occur without first metatarsal plantarflexion)
instant centre of rotation must be mobile (may depend on first metatarsal head shape)
About 65 degrees is considered as being needed for normal function (Hopson et al, 1995)
Hopson et al (1995) and Nawoczenski et al (1999) showed that the range of motion obtained during static measurement of the first MPJ was greater than the range used during dynamic function.