Stress fractures were once most common among military personnel who marched and ran day after day. But today, stress fractures are on the rise in athletes, from distance runners and sprinters to skaters, hurdlers, and tennis, volleyball, soccer, and basketball players. Dancers and gymnasts are not immune either. Men and women in these two sports who train more than five hours a day have been shown to be 16 times more likely to develop a stress fracture.

A stress fracture is a hairline crack in the bone that can grow larger over time if not treated properly. There are two types of stress fractures. Insufficiency fractures are breaks in abnormal bone under normal force.

Fatigue fractures are breaks in normal bone that has been put under extreme force. Fatigue fractures are usually caused by new, strenuous, very repetitive activities, such as marching, jumping, or distance running. The main focus of this update (review) article is on fatigue stress fractures among athletes.

Besides being a soldier or an athlete, being a female in either of these groups increases the risk of a stress fracture. Other risk factors include biomechanics (alignment of the foot, ankle, and lower leg), muscles mass and strength, and bone density and bone geometry (shape, thickness).

One of the new findings in risk factors is the cross-sectional diameter of the long bones of the leg. For example, a smaller cross-sectional area of the tibia (lower leg bone) has been linked with stress fractures in male runners. The cross-section of a bone is the width of the bone you would see if that bone was cut straight across (sideways not length-wise). The thickness of the bone seen this way represents the bone strength.

There's not much a person can do to change the cross-sectional area of the bone or gender (male versus female). But there are ways to prevent stress fractures by modifying other risk factors. For the athlete with flat feet, forefoot malalignment, excessive hip internal rotation, uneven leg length, or other biomechanical factors, an insert placed inside the shoe can make a big difference.

For women who are overtraining while also limiting calories, a better balance of eating and nutrition may be helpful. Females who have an eating disorder or disordered eating are common among athletes where "lean is mean" (a desired state of body and mind) in some sports. In such cases, nutritional and behavioral counseling are advised.

Training schedules can also be reviewed and altered if training is too much, too often, too long, or too intense. A sudden change in the athlete's training routine (increased intensity and/or duration) is the biggest training error leading to stress fractures. Gradual increases in training may be able to avoid this mistake.

Muscle mass and muscle strength can be increased with a strength training program. Smaller muscles and muscle fatigue may result in an increase in the force placed on the bone with activity. Women may be at increased risk of tibial (lower leg bone) stress fractures because the female's calf muscle just isn't as large as the male's.

And with excessive training, muscle fatigue may result in a change in postural alignment and body mechanics -- all adding up to more force transmitted from the ground up the leg and into the bone. But athletes worry that they will lose their edge in fitness if they decrease their training volume. They are not gung-ho about backing off their training schedule.

A review of training surface and shoe wear may be all that's needed before altering the training schedule. And for those who do need to pull back a bit, studies show for the already fit athlete, reducing the training volume temporarily does not affect athletes' ability to perform and compete effectively. Lower levels of fitness may actually be a risk factor for stress fractures. So for some athletes, bumping up the fitness portion of their training may be a good idea.

These prevention ideas are all very good but how does an athlete with various aches and pains know when a stress fracture has already developed? The most common symptom is increased pain with specific sport activities (e.g., increased shin bone pain when running or jumping). If the athlete presses on through the pain, then typically, pain will be present at rest as well.

Pressure on the painful area increases the pain. Hopping on that leg also reproduces the severe pain often present with activity. There may be swelling around the painful site. The physician or other examiner can perform a tuning fork test (pain is reproduced when a vibrating tuning fork is placed over the painful area). But the fastest and most accurate way to diagnose a stress fracture is with an MRI.

Once it is certain that the problem is, indeed, a stress fracture, then treatment becomes a matter of management. Rest and avoiding activities that cause pain are the first two steps. The athlete can still participate in a fitness program so long as it does not cause any pain. Swimming, pool-running, and bicycling are usually safe bets.

Tibial stress fractures seem to respond faster when the athlete wears a special pneumatic leg brace. A cast on the foot and ankle may be needed for foot stress fractures. In those cases, the athlete is non-weight-bearing (using crutches) and cannot continue with training that involves the fractured foot/leg.

Surgery is not a main line of treatment for most stress fractures. Fracture fixation with screws, wires, and/or a metal plate may be needed for stress fractures that progress to a full fracture with displacement (ends of the fractured bone separate) or for stress fractures of the hip.

Regardless of the treatment provided, there should always be a re-evaluation of the athlete and gradual return to sports activities, fitness regimens, and training schedules. All risk factors should be assessed and modified wherever possible. Nutrition is a vital key for all athletes but especially women who are already at greater risk for stress fractures than their male counterparts.

Reference: Amanda K. Weiss Kelly, MD, and Sharon L. Hame, MD. Managing Stress Fractures in Athletes. In The Journal of Musculoskeletal Medicine. December 2010. Vol. 27. No. 12. Pp. 480-486.