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There are three Arches of the Foot:
First Arch: the longitudinal arch (long arch) runs from heel to the toes. (See Ar 1)
Second Arch: the distal transverse arch runs like a little bridge from big toe to little toe at the ball of the foot. (See Ar 2)
Third Arch: the middle transverse arch, which we are more familiar with, is located in the instep of our foot. It is the rise in the instep that runs in front of the heel. The arch padding in the instep of a shoe is usually placed under this arch. (See Ar 3)
Foot Biomechanics
The foot serves as a shock absorber during the heel strike through foot flat phase of walking. As we begin to step forward, our front leg swings with the arch fully raised in preparation to strike the ground. The outer heel strikes the ground first and weight is taken from outside of the foot to the inner side as the arch lowers. (See Ar 4) Our arches are like flexible cups that lower toward the floor to absorb our weight. This lowering is called pronation and is a normal part of walking. (See clip Ar 4.5) Arches should ideally rise completely to be ready for the next step. This are rising is called supination. If arches do not return to their full height, they provide only partial shock absorption as they hit the floor.
The legs should be rotating inwards upon arch flattening, then rotate back outwards during the arch reforming phase. (See clip Ar 5, 6) When the arch remains in a lower position and full arch height is not restored, the normal outward rotation all the way up the kinetic chain (knee, hip and back) is also reduced. Strain and chronic pain syndromes in knee, hip and back may result. (See Ar 7)
As we go to step off our foot, the lower leg rotates outwards, the bones of the foot lock in order to provide rigid leverage needed to push off the ball of our foot. A well-formed arch helps hold the bones of the foot in a position of mechanical advantage as a solid lever for push off.
When someone who has no arch at all tries to rise up on their toes, they cannot go as high as someone who has a normal arch.
Hence the foot is both a shock absorber during one phase, then a rigid lever in the next phase. Pronation (flattening) and supination (arch raising) are normal movements of the feet in normal walking. The normal foot also works with the rotary movements of shin, thigh and pelvis in a coordinated way. (See Ar 8)
Pronated foot type
Generally a person whose arches are weak and low to the ground when standing has a pronated foot type. (See Ar 10)
A person born with flat feet will generally have flat feet while sitting and standing. (See Ar 8.75)
These people are born without the spring ligament that gives form to the middle transverse and longitudinal arch. (See Ar 8.5) So when runners say they have pronated feet it can mean their arches are flattening too much during the phase where pronation should occur in moderation. It may also mean that they never attain full supination, so the arches start too low and end up too low.
A Supinated foot type
A person whose arches are very high is usually considered to have a rigid, supinated foot type. (See Ar 8.9) They can experience more difficulties on the outside edge of their foot because more weight is borne on the outside than the inside. However a high arch can become weakened over time if the arch is not supported well. A high arch has further distance to flatten, and the soft tissue over-stretches to allow the big toe to reach the ground. This type of foot tends to need softer arch support rather than rigid control.
Rearfoot/Forefoot Problems
To determine if forefoot or rearfoot problems are present, the foot must be viewed from behind while it is in a non-weight bearing position with ankle held in neutral position. Neutral ankle position is when the talus (See Ar 8.95) is in the middle of the two anklebones. Ideally the heel should align with the length of the leg. (See clip Ar 9) If the heel bone is tipped to the inside or outside, it can require a lateral or medial wedge (posting) to help straighten it. (See Ar 9.5)
If the balls of the foot are tipped up on the outside or inside relative to the horizontal plane, corrective padding (posting) may be required under the forefoot to level it. (See Ar 10.5)
To reiterate: there can be specific modifications made to a custom orthotic which are meant to put the heel and front foot in the optimum position to normalize the biomechanics of the foot. This means that the heel bone is upright; the arch is maintained and the first and last ball of the foot are level as well as perpendicular to the heel. (See Ar 11)
Before this type of correction is made, however, it is advisable to ensure the normal functioning of all the muscles. A tight calf muscle will pull the heel bone slightly in (varus). A tight calf will also limit ankle bending, which in turn flattens the arch to compensate for getting the heel down to the floor.
If ankle bending is limited, another way of compensating can be to sweep the foot up to the outside in a circumduction pattern. For normal walking 10° of dorsiflexion is ideal. (See Clip Ar 11.5) When running dorsiflexion can be seen in Clip Ar 11.75. Simple stretching exercises for both calves are important to normal foot mechanics. Note in clip Ar 13 the therapist corrects the foot angle for reduced strain on the arch and knee. (See clips Ar 12, 13, 13.5)
Orthotics (Arch Supports)
There are many brands of prefabricated orthotics, which can be a starting point when trying to better support your arches. I recommend a softer type of insole for people with mildly lowered arches.
This is considered an accommodative approach rather than a corrective one. Spenco brand has several kinds and they can be bought at sporting goods stores. You can buy simple insoles for cushioning, ones with foam added for arch support, as well as ones with harder plastic on the underside for more rigid support. Pricier ones, such as Lynco brand are also available, many of which have built corrections and can be bought from Orthopodiatric fabricators. I usually recommend full-length supports as they slide around less in the shoe and provide cushion under the ball of the foot.
Some full-length orthotics cannot fit in existing shoes, so shoes with an extra width size should be purchased. If you must keep your old shoes then the partial length orthotics can be used in them, providing that cushion under the ball is not a factor in comfort.
Custom orthotics are a better choice when there is a big difference between the arches of the two feet, or when there are forefoot and rearfoot imbalances. Therefore, more precise correction (posting or wedging) can be made. The two ways to make plaster casts of the feet are by either neutral casting or foam box methods. Neutral casting has long been considered the most accurate method for feet in need of considerable correction.
While a person is lying on a table their foot is actually wrapped in plaster wrapping material and ankle held in a neutral position. (See clip Ar 14) A plaster model is made from this shell. It is messier and takes more time and skill to administer. Foam box molding has become more popular for its ease of use, lower cost and less skill needed to take the impression. While sitting, one's foot is gently lowered onto a crushable piece of foam in a box. Some minimal weight is put onto the foot while the ankle is held in neutral. A plaster model is made from the impression. Some Orthopodiatric fabricators use computer generated methods for making orthotics. Most custom-made orthotics are made from a hard plastic if you don't request an alternative.
This more rigid orthotic is necessary for very flat feet or those who place a greater load on their feet. This would include people who are overweight, people stand a lot or who run and jump. There are other lighter materials available like puff, plastizote, pealite and nickleplast that can offer softer support for feet that requires less control. Remember, a normal arch should fall a little then return to its raised position. A very rigid orthotic under a sensitive foot or under the foot of a fairly small individual may not have enough give to it and can create more discomfort in the arch. A high arched foot may just need a greater volume of flexible material, not rigid control. Many custom-made orthotics stop just behind the ball of the foot and provide no cushion under the ball.
A full length orthotic or one with a neoprene extension under the balls will provide extra comfort. Remember, one arch may be higher or lower from right to left, in which case custom made supports whether corrective or accommodative are more helpful in the long-term. Prefabs may do for the short term and can reduce the cost of putting them multiple pairs of shoes you don't wear as often.
Buying Shoes that work with your Orthotics
Lace-up shoes offer the greatest support and adjustability when arch supports are used. Slip on shoes or boots cannot be hugged into the arch of the foot so are they are OK occasionally for dress but should not be worn for substantial walking/standing on a daily basis.
Most sturdy shoes have an insole that can be removed to accommodate a new prefabricated or custom arch support. Some insoles are glued in and take a bit of prying to remove. Women's dress shoes often have only a thin liner and can only accommodate a simple foam replacement insole not an orthotic. Bring your orthotics or insoles with you to test the fit when buying new shoes. (See Foot Care tips on buying new shoes.)
Shoes that will have to accommodate a full orthotic need to be bought at least a size or size and a half wider than normal, but not longer. For persons with orthopedic or diabetic foot problems a special shoe with built in extra depth can be purchased from a pedorthotist.
For diabetic foot problems the insole that is fabricated is often soft and 1/2" thick in order to support more vulnerable tissues.
Remember, excess shoe wear creates problems all the way up the kinetic chain. When the heel is worn 1/4" it must be replaced! Check your shoes for wear every 6 months. Otherwise the heel is tipped as it contacts the ground. Strain on knees, hips and back can result. Similarly the front sole of a shoe should be replaced when one edge is worn down between 1/8-1/4"; otherwise the ball of the foot sinks lower than it should on push-off. Runners should budget for new shoes every 6 months. Orthotics can last 6 months to 2 years depending on the amount of load they carry and how much walking is done.
If you have any back, knee or hip strain, it may be time to replace orthotics or resole your shoes. Consider using some kind of arch support if you are having any knee, foot or back pain.
Strengthen your feet. Doing gentle foot exercises throughout the day can be very helpful, especially if done before you know you will be on your feet a lot, like for social events, conventions, vacations and working on ladders. If you carry heavy loads to or for work, remember that although temporary, the extra weight that is carried is transmitted to your feet. Therefore your feet must be strong and well supported. During pregnancy strengthening and supporting your feet is especially important.
Learn to use the full coordinated movement of your body when walking. The Alexander Technique and Feldenkrais Method can help you develop greater awareness and kinetic participation of your whole body. Just using arch supports doesn't mean you know how to use your arches!
Also see Foot Care.
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