A stress fracture is a small crack in a bone. They often develop from overuse, such as from high-impact sports like distance running or basketball. When muscles are overtired (fatigued), they are no longer able to absorb the shock of repeated impacts. When this happens, the muscles transfer the stress to the bones, creating a small crack or fracture.

Most stress fractures occur in the weight-bearing bones of the foot and lower leg. The most common sites are the second and third metatarsals of the foot. Stress fractures are also common in the heel (calcaneus), the outer bone of the lower leg (fibula), and the navicular, a bone on the top of the midfoot.

• Athletes who participate in high-impact sports, such as track and field, basketball, gymnastics, or tennis
• Dancers (ballet and other) are susceptible to stress fractures because of the repetitive impact of dancing
• Women, particularly female athletes, with abnormal or absent menstrual cycles (This can result in decreasing bone mass.)
• Military recruits who suddenly shift from a sedentary civilian life to a more active training regime
• Exercisers who have made a sudden change in their weight-bearing training

Stress fractures usually occur when you increase your high-impact activity by frequency (how often you exercise), duration (how long you exercise), or intensity (your level of exertion). Stress fractures can also occur with normal usage if bones have been weakened by osteoporosis or other disease. These fractures are often called "insufficiency fractures" because there isn't enough bone to withstand the normal stress of daily use.

• Pain that develops gradually, increases with weight-bearing activity, and diminishes with rest
• Pain that becomes more severe and occurs during normal, daily activities
• Swelling on the top of the foot or the outside of the ankle
• Tenderness to touch at the site of the fracture
• Possible bruising

If you suspect a stress fracture in your foot or ankle, stop the activity and rest the foot. Ignoring the pain can have serious consequences, and the bone may break completely.

Apply an ice pack and elevate the foot above the level of your heart. Non-steroidal anti-inflammatory medication (NSAIDs) may help relieve pain and swelling.Try not to put weight on the foot until after you see a doctor.

Stress fractures are difficult to see on X-rays until they have actually started to heal. Your doctor may recommend a bone scan, which is more sensitive than an X-ray and can detect stress fractures early.

Treatment depends on the location of the stress fracture. Most stress fractures will heal if you reduce your level of activity and wear protective footwear for 2 to 4 weeks.

Your doctor may recommend that you wear a stiff-soled shoe, a wooden-soled sandal, or a removable short-leg fracture brace shoe. Athletes should switch to activities that place less stress on the foot and leg. Swimming and bicycle riding are good alternative activities.

Stress fractures in the fifth metatarsal bone (on the outer side of the foot) or in the navicular or talus bones take longer to heal, perhaps as long as 6 to 8 weeks. Your doctor may apply a cast to your foot or recommend that you use crutches until the bone heals. In some patients, surgery may be needed to ensure proper healing.

Once your stress fracture has healed and you are pain-free, your doctor will allow a gradual return to activity. You should slowly increase the frequency, duration and intensity of your exercise. During the early phase of rehabilitation, your doctor may recommend to alternate days of activity with days of rest. Cross-training (varying the types of aerobic exercise you do) may help you avoid doing too much impact too soon.

Stress fractures that don't heal properly can develop into complete breaks of the bone and can become a chronic problem; therefore, it is better to prevent them in the first place.

Here's what you can do to prevent stress fractures:

• Maintain a healthful diet. Eat calcium and vitamin D-rich foods to help build bone strength.
• Use the proper sports equipment. Don't wear old or worn running shoes.
• Alternate your activities. For example, you can alternate jogging with swimming or cycling.
• Start any new sports activity slowly. Gradually increase time, speed, and distance; a 10% increase per week is fine.
• Strength training can help prevent early muscle fatigue and prevent the loss of bone density that comes with aging.
• If pain or swelling returns, stop the activity. Rest for a few days. If pain continues, see an orthopaedist.