Quad A Gait Description
The Quad A Foot-Type is commonly thought of as an over-supinated or severe Pes Cavus foot. This condition, also
known as a Torque Foot, occurs when a Uncompensated Rearfoot Varus is coupled with a Large Rigid Forefoot
At initial contact, the calcaneus of the Quad A foot-type strikes the ground in an excessively inverted or supinated
alignment relative to the floor. Since the rearfoot varus deformity is uncompensated, very little subtalar joint
pronation is observed as the forefoot is lowered to the ground to conclude the contact period of gait. The valgus
alignment of the forefoot subjects the 1st metatarsal head to excessive and premature forces. In turn, the peroneals
contract early in order to offset excessive supination of the subtalar joint. Also, because of the lack of subtalar joint
pronation, there is significant loading force on the lateral side of the heel causing poor shock attenuation.
As weight moves forward over the foot, the arch and midtarsal joint remain rigid, with excessive pressure borne
along the lateral column and base of the 5th metatarsal. Normally by this point in the gait cycle, weight begins to
transfer from the lateral side of the foot over to the medial side. Instead, in the over-supinated Quad A foot-type,
this weight transfer does not occur.
In propulsion, the gastrocsoleus contracts, plantarflexing the ankle and initiating heel rise. The gastocsoleus also
functions as an ankle invertor, since it’s insertion lies medial to the subtalar joint axis. As the rearfoot is already
overly supinated in this foot-type, any additional supination caused by the contraction of the gastrocsoleus can lead
to lateral ankle instability and the potential for sprains. As the subtalar joint moves into more and more supination,
significant pressure is exerted on the head of the 5 th metatarsal.
In terminal propulsion, the neuromuscular mechanisms of the body act to prevent spraining of the ankle. The foot
and ankle must either rapidly pronate to shift weight back over to the 1 st metatarsal; or, in many cases, a person with
this Quad A foot-type will simply end their step early (short steppers).
Rapidly pronating the foot from the lateral to medial side in terminal propulsion creates pressure and instability
across all the metatarsal heads. This results in heavy callus formations (particular the 1st and 5th metatarsal heads),
hallux abductovalgus deformity, and hammertoes. Imagine grinding a rolling pin back and forth over the ball of the
foot every step you take! This rapid and repeated transfer of weight from the medial to lateral, and back to the
medial side of the foot is referred to as the “supinatory rock”.
We fondly refer to this foot-type as our "chandelier shakers"! Why? Because this foot-type loads heavily on the
ground and never seems to pronate, leading to poor shock attenuation. The development of heel and lower back pain
is common. The torque foot nature of this foot-type allows the valgus forefoot to offset the uncompensated inverted
heel alignment that would normally lead to a toe out gait pattern (see C Quad foot-type). Overall, the foot
progression angle for this person is such that the feet point relatively straight ahead during gait (no toe out) with a
narrow base of support, much like a tight rope walker.
Poor Shock Attenuation