Abnormal foot posture results from structural abnormalities within the foot. When the foot is not bearing any weight, structural abnormalities aren't significant. When weight is put on the foot during walking and running, the foot has to compensate for any structural defect, according to FootMaxx.com, in order to achieve forward momentum, or propulsion. The foot compensates by pronating, or moving out, up and to the side, and by supinating, or moving down and in.
Types of Structural Deformities
There are five common structural deformities of the foot. Rearfoot varus is the most common condition, occurring in nearly 85 percent of the population, according to FootMaxx.com. In standing, rearfoot varus causes the heel of the foot to be tilted inward, or inverted, relative to the ground. In forefoot varus, the position of the front part of the foot, the forefoot, is inverted relative to the back of the foot, or rearfoot. In equinus, the ankle cannot flex upward past 10 degrees, so the mid-foot joints collapse in order for the foot to achieve propulsion. A plantarflexed 1st ray is a displacement, causing the 1st metatarsal, the long bone, to sit lower than the other four metatarsals. Forefoot valgus results in the forefoot being tilted outward, or everted, relative to the rearfoot.
Overpronation
Pronation is a motion that normally occurs at the subtalar joint, located just under the ankle, during gait in order to shift the weight from the rearfoot to the forefoot for propulsion. In the presence of structural abnormalities, the subtalar joint can compensate by pronating too much, called overpronation. Forefoot varus is responsible for causing the most severe pronation problems. According to Foot.com, overpronation can lead to injury and pain in the foot and ankle.
Oversupination
According to SportsInjuryClinic.net, normal supination causes the foot to remain rigid for propulsion during the gait cycle. Oversupination does not occur as often as overpronation does, and is associated with a rigid forefoot valgus foot type. Oversupination reduces the amount of shock absorption taking place during the gait cycle, leading to overuse injuries.
Problems
Each structural abnormality can cause its own set of problems. According to FootMaxx.com, rearfoot varus can lead to heel spurs, leg fatigue, knee and back pain. Forefoot varus can cause the formation of plantar fasciitis, neuroma, tendinitis and low back pain. Equinus can lead to hammer toes, severe postural problems and fatigue of the leg muscles. A plantarflexed 1st ray can cause plantar fasciitis and lateral knee pain. Forefoot valgus can lead to ankle pain, hammer toes and plantar fasciitis.
Treatment
Custom-made arch supports, called orthotics, are worn inside the shoes and can help re-balance the foot, decreasing the amount of problems associated with an abnormal foot posture. According to PodiatryNetwork.com, functional foot orthotics are used to correct abnormal foot function. They can be made from several types of materials, such as flexible, semi-rigid or rigid plastic, in order to provide the best result. Since some types of ankle, knee and back pain are associated with abnormal foot posture, orthotics can be used to treat them.
