Understanding Stress Fractures

by Dr. Cathy Fieseler
(first of a two part series)

Another relatively common running injury is a stress fracture. My experience in my medical practice is that women comprise half of my stress fracture cases, but are four times more likely than men to suffer a recurrent stress fracture.

To understand stress fractures, a basic understanding of bone physiology is helpful.
When stress is applied to bone (running), the bone breaks down and then rebuilds, becoming stronger than it was initially. The problem arises when too much stress is applied; the breaking down process overrides the rebuilding. This leads to micro-fractures and eventually a stress fracture. With additional impact, a stress fracture can become a complete break.

The tibia (large shin bone) is the most common site for stress fractures in runners, followed by the metatarsals (long bones in the feet that connect to the toes). The fibula (small shin bone), femur (thigh bone), navicular (bone in the center of the arch of the foot) and pelvis may also be injured.

The potential complications of a stress fracture depend on which bone is involved. A stress fracture of the femur, especially at the hip can be catastrophic if a complete fracture occurs, whereas a stress fracture of the fibula has minimal long term consequences.

Diagnosis

Pain is the presenting symptom with a stress fracture. Subtle swelling may be present at the site. Typically pain occurs with running and resolves when the activity is completed. With continued running, the pain increases and persists with walking. In severe cases, pain is present at rest.

There is pain on palpation of the affected bone. In some cases, such as a hip stress fracture, the bone cannot be palpated. The surrounding muscles may become inflamed which may lead to an incorrect diagnosis of tendinitis.

The hop test is very useful. I will ask an injured runner to stand on the affected leg and hop. If a stress fracture is present, the runner is often unable to hop. If she can hop, it is usually a feeble, painful jump. If there is minimal discomfort with a single leg hop, a stress fracture is less likely.

Stress fractures are not seen on x-rays for at least two weeks (and sometimes quite a bit longer) following the onset of symptoms. An MRI or bone scan will demonstrate the abnormality within 48 hours of its development.

Treatment

The treatment of a stress fracture will include cessation of running. If there is pain with walking or in the case of certain stress fractures (hip, navicular) the runner will be placed on crutches. Non-impact cross training is usually fine and includes swimming and pool running. Cycling and using an elliptical trainer or Stairmaster may be allowed, depending on the runner’s weight bearing status. The length of treatment is based on the specific bone involved. On occasion, surgery may be recommended due to the high risk of poor healing with certain stress fractures.

When the injury has healed sufficiently, impact exercises are gradually re-introduced. The running base must be re-established before any high intensity workouts are initiated.
The most important factor is to determine the cause of the stress fracture and correct it. Training errors are the most common cause of running injuries – too much, too fast.

Anatomic issues, especially high arched feet, may increase the likelihood of developing a stress fracture. Low bone density also increases the probability of a stress fracture; this is often due to a low estrogen level, which occurs in menopause and may also occur in younger women due to stress related loss of the menstrual cycle. Exercise is one of the life stressors that may lead to amenorrhea (loss of menstrual cycle), especially high levels (intensity and/or amount) of exercise in conjunction with inadequate nutrition.

A well planned training program, adequate nutrition (including calcium and Vitamin D) and appropriate recovery from training are necessary elements for healthy running.

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Bennett Cohen (the Savvy Runner) and Gail Gould are the Founders and Presidents of the International Association of Women Runners (IAWR). To learn more about this global community of women who share a passion for running, visit www.iawr-connect.com.

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