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The Quad B Foot Type is a mildly over-pronated foot type. This is the result of a Compensated Rearfoot Varus with a flexible forefoot valgus deformity. It is often to be found unilateral and is often associated with a structural leg length discrepancy.
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Contact Phase
Midstance Phase
Propulsion Phase
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OBSERVATIONS
- Low-Medium Arches
- Toe-In Gait
- HAV Deformity
- Partial Midtarsal Joint
Instability
- Often Unilateralbility
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Click on Image to go to Orthotic that is right
for Quad B Foot Type
 
 
 
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The Quad B Foot Type is a mildly over-pronated foot type. This is the result of a Compensated Rearfoot Varus with a flexible forefoot valgus deformity. It is often to be found unilateral and is often associated with a structural leg length discrepancy
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The Quad B foot-type is a rarely occurring combined foot deformity, affecting less than 10% of the population. In addition, it is often unilateral. The Quad B foot-type is a mildly over-pronated foot due to a compensated rearfoot varus deformity, however that over pronation is somewhat minimized by a forefoot valgus deformity that acts like a "pronation-deterrent".
In some cases, the incidence of this foot-type may be caused by an acquired plantarflexed 1st ray, functioning as a forefoot valgus. This may occur in flexible pes planus foot types as the peroneals are working overtime to try and pull the forefoot into a pronatory twist in attempt to stabilize the midtarsal joint. It is also common to see this condition occur unilaterally on a short limb. Pronating the forefoot into a valgus alignment supinates the foot and helps lengthen the limb. When this foot-type occurs on one side only, we refer to this as a "foot disparity". When foot disparities occur, each foot functions differently from one another, as so each limb functions differently as well. This has a direct affect on the hips and low back, often leading to sacral-iliac pain.
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.
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Contact Phase
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| At initial contact, the calcaneus strikes the ground in a slightly inverted alignment relative to the floor. Since the rearfoot varus is primarily compensated, like the D Quad Foot-type, the subtalar joint immediately pronates at heel strike. Unlike the Quad D foot-type, however, the calcaneus does not evert to a completely vertical position since the Quad B Foot-type is coupled with a forefoot valgus. The presence of the forefoot valgus causes premature loading of the 1st ray at foot flat. This early 1st metatarsal head loading actually has a beneficial effect in that it helps to decelerate subtalar joint pronation and prevents the midtarsal joint from becoming too mobile. One more important observation is that during gait the foot progression angle is toe-in. .. |
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Midstance Phase
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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 |
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Propulsion Phase |
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As the heel lifts off the ground, initiating the propulsive period of gait, you will notice the foot does not break down laterally at the oblique midtarsal joint as was seen in the Quad D foot-type. This is because midtarsal joint stability is gained by the coupling of the compensated rearfoot varus with the forefoot valgus in the Quad B foot-type. In this respect, we suggest that a small forefoot valgus (i.e. less than 6°) is not necessarily a bad thing.
Unfortunately, if the forefoot valgus is more severe (i.e. greater than 7°), there will be excessive loading on the 1st metatarsal head that will eventually drive it dorsally, causing trauma to the sesamoids and partially transferring weight to the 2nd metatarsal head. Final propulsion is shared between the 1st and 2nd metatarsal heads. Furthermore, there is increased activity of the abductor hallicus and flexor hallicus longus, along with progressive instability of the 1st ray that will gradually lead to hallux abductovalgus deformity. In gait you will notice as the degree of the forefoot valgus deformity increases, so will the degree of the toe in gait pattern. |
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