Just as no two feet are exactly like, the same goes for customized orthotic inserts -- molded from a plaster cast of the foot and then tailored to the wearer's lifestyle and biomechanical irregularities.

"If you have a 90-year-old walker, you're going to put her in a softer orthotic that provides cushioning but not as much control," says John Pagliano, a Long Beach, Calif., podiatrist and spokesman for the American College of Sports Medicine. "On the other hand, a 300-pound pro athlete is going to need a stiffer and heavier orthotic that can hold weight. It's different for everyone."

The following are the main types of custom shoe inserts, according to the American Podiatric Medical Association:

Rigid orthotics Made of firm materials like plastics, fiberglass and carbon fiber, these primarily address motion in two major foot joints below the ankle. If your doctor suspects that a foot imbalance is the cause of pain in the leg, thighs or lower back, he may prescribe rigid orthotics, which are usually designed for use in walking or dress shoes.

Semi-rigid orthotics These act as a balance aid during walking or athletic activities. They are made from foam with a thin, plastic shell laminated to it.

Soft orthotics Designed to act as shock absorbers and also to increase balance and reduce pressure in sore spots, these inserts are made of compressible foam. They have proven effective for arthritic feet and are also widely used to care for diabetic foot conditions. They tend to be bulkier than other inserts and may require extra room in shoes or prescription footwear.

Children's orthotics These are primarily used to treat children with foot deformities, generally starting soon after a child begins walking. Inserts usually must be replaced when the child's foot grows two sizes.

Sport-specific orthotics For more serious athletes, these inserts are designed to provide efficient foot movement during particular sports.

Whatever the case, orthotic rookies shouldn't expect to feel like a million bucks right out of the chute. In changing the position of the foot, the inserts also place the joints and tendons at new angles, so it takes time for the body to adjust and feel comfortable. That's why Pagliano recommends wearing them for only an hour or two per day initially and gradually building up.

With customized inserts running $300 to $500 a pair, insurance coverage can be a decisive factor for some buyers. While insurance restrictions vary, major carriers generally provide coverage only when orthotics are prescribed for specific foot injuries, say from arthritis or diabetes, or deformities -- for example, heel spurs, tendinitis or bunions, according to Lloyd Smith, vice president of the American Podiatric Medical Association and a Newton, Mass., podiatrist. "You have to come with a pain diagnosis of some sort. Then you have a reasonable chance of reimbursement from national insurance agencies. They do have criteria, but they're not going to tell you what their criteria are."

Even when patients do receive coverage, most insurers will pay for only one pair per year, says Pagliano. This means people wanting to outfit both their everyday shoes and athletic footwear will either have to foot the bill for the second pair or wait; inserts made for athletic footwear generally won't fit narrower dress shoes, and vice versa. "The upside," says Pagliano, "is that once you've made the cast of the foot, you can make a second pair of orthotics for half the price."

In some cases, customized inserts are not even needed. Mild foot problems can often be remedied with over-the-counter orthotic inserts, which sell for $20 to $30. "We think the over-the-counter products are pretty good these days," says Pagliano. "If you come in and see a doctor, they can tell you what kind is best for you."

-- Dallas Hudgens