Improper shoe fit can limit joint movement, constrict circulation, decrease proprioceptive input, and alter gait. Poor shoe fit can also inhibit the proper functioning of custom-made foot orthotics. Any of these factors can and usually will affect the entire kinetic chain -- from the feet all the way up into the pelvis and spine. Over the long term, the muscles, joints, and connective tissues in the feet can all suffer and undergo degenerative changes. In fact, shoes have been implicated as the principal cause of forefoot disorders in females. [1] Your patients' shoes will contribute either to their health and spinal balance, or to their misery and spinal complaints.

Shoes are designed to protect the feet during their primary functions of mobility and support. Over the past century, fashion has frequently interfered with the original purposes of protection from injury and exposure. Footwear is sometimes the cause of, and frequently a contributor to, musculoskeletal disorders. Let's review the important factors of size, shape, and support.

Shoe fit is a combination of size and shape characteristics. Proper shoe size accommodates the first metatarsophalangeal (MTP) joint in the widest part of the shoe. This is termed a "ball fit," and allows for correct function of the MTP joints. Since toe lengths vary greatly, a shoe fitted by overall length may be under-sized. All fitting and sizing must be done weight-bearing, because the foot lengthens and widens under physiologic loading as the day progresses. When standing, there should be 3/8" to 1/2" from the longest toe to the end of the shoe. [2] One important study found that 88% of women tested were wearing shoes that were too small for their feet. [3]

The second component of fit is shoe shape. Several factors combine to make up the overall shape. The most important are: the last, toe box, vamp, and heel counter.

*** The last. The last is the "footprint" that the shoe is designed upon. Most everyday and dress shoes are built on a "straight" last, while athletic shoes use a "combination" last, which accounts for the normal slight inward curve of the forefoot. A straight last provides more support during pronation, and is recommended for patients using orthotics.

*** The toe box. The toe box must be wide, high, and long enough to allow movement of the toes. A narrow toe box will crowd and pressure the metatarsals and phalanges, while a short toe box will jam the toes and cause nail pressure problems to develop (especially in athletes). An unnatural narrow shape will cause calluses and discomfort, with possible deformity and clinical problems.

*** The vamp. The vamp is the material over the instep. The ideal vamp contains laces for an adjustable fit. The vamp must be high enough to prevent pressure on the instep. Pumps and slips-ons often have little or no vamp, requiring a too-tight fit to prevent the shoe from falling off. A vamp that has been "pushed over" the edge of the sole is a sign of improper shoe fit and probable biomechanical problems in the foot. A too-narrow vamp forms a "cast" -- crowding bones and impairing circulation and joint mobility.

*** The heel counter. The heel counter supports the calcaneus, prevents shoe slipping, and helps control rear foot motion. A straight and solid heel counter can be enough support to prevent excessive pronation in young and lighter-weight patients. When the heel counter breaks down, it gives telltale clues of the foot's tendency to pronate or supinate.

The shank is the inner part of the shoe that extends forward from the heel. Its purpose is to prevent excessive pressure on the medial longitudinal arch of the foot. A shoe with a weak or non-existent shank provides poor support and will contribute to over-pronation and eventual breakdown of the longitudinal arch. The heel counter and vamp combine to provide lateral support and prevent rolling over the sole, both medially and laterally.

Since your patients take 5,000-10,000 steps each day, mostly on hard surfaces, their entire musculoskeletal systems are being punished if their shoes do not fit correctly. Take a moment to evaluate the shoe type, condition, and fit. This can frequently provide clues to your patients' problems, and is not uncommonly the source of their aching back, sore knees, and body fatigue.

The use of custom-made, flexible orthotics can make up for many lower extremity biomechanical problems. However, a poorly fitting or non-supportive shoe will compromise orthotic function and support. The best combination is a custom-fitted, flexible orthotic with shock-absorbing materials worn in a ball-fit shoe with a good heel counter and a strong shank. Always keep in mind that custom orthotics are made for the feet, not for the shoes.

1. Frey C. "Foot health and shoewear for women." Clin Orthop 2000; 372:32-44.

2. Janisse DJ. "The art and science of fitting shoes." Foot & Ankle 1992; 13:257-262.

3. Frey C, Thompson F, Smith J, Sanders M, Horstman H. "American orthopedic foot and ankle society women's shoe survey." Foot & Ankle 1993; 14:78-81.