What is a "stress fracture" and how should it be treated?

Stress fractures – or "March" fractures, as they are known in the military (because they frequently develop from marching) – are common injuries that can occur in the lower extremity, especially among athletes. There is a disruption in the continuity of normal bone caused by repetitive microtrauma to an area. A stress fracture develops over a period of many days, weeks or months. By contrast, acute trauma typically results from one incident – a fractured ankle from a severe twist, for example, or a fractured metatarsal from a heavy object falling on it.

There are two theories about the cause of stress fractures. One is that muscle fatigue secondary to repetitive stress causes a loss of shock absorption that, in turn, allows the force to be transferred to the bone. The second theory is that repeated muscular forces acting on the bone produces the stress fracture. It is likely that both theories contribute to the development of stress fractures, although the amount that each contributes may vary in individual cases.

The typical scenario is that an athlete develops localized pain and swelling. The pain worsens with activity and improves with rest. The onset of pain and swelling is usually gradual and may hardly be noticeable at first. There is generally no history of an obvious injury to the athlete. Usually the athlete will tell of participating in a new strenuous activity, increasing the intensity of an old activity or participating at a very high level for a long period.

The diagnosis is made through a careful history and physical. The examination usually reveals a discrete area of pain during palpation and percussion, localized swelling and redness. Sometimes the patient will be unable to hop on the affected extremity because of pain. X rays may show signs of a stress fracture – although x rays are usually normal for about 10-14 days after the onset of pain and swelling. In some cases, the signs of a stress fracture may not show up on an X ray for as long as four or five weeks or may never show up on a conventional X ray. Other forms of imaging, including bone scans, CT scans and MRIs, may detect a stress fracture that does not show up on conventional X rays.

Treatment for stress fractures consists of relative or absolute rest. This will depend on the bone or bones involved, and the severity and stage of the fracture. The activity that caused the injury must be avoided to prevent delayed or improper healing. Athletes wishing to maintain their fitness level may participate in low-impact activities such as swimming, biking or water running – but, again, this would depend on the bone fractured and the stage of healing. Casting or bracing may be indicated for stress fractures that are at risk of complete fracture or displacement. A period of non-weight bearing with crutches may be helpful along with the use of anti-inflammatory medications.

When the rest period is complete and the patient has remained pain-free for two weeks or so, supervised rehabilitation is initiated along with a gradual return to activity. Returning to activity too early or increasing the amount of activity too quickly may initiate the stress fracture process again. Care should be taken during the first four weeks since this is the most vulnerable time during a fracture’s reparative process.

Preventing another stress fracture involves identifying and eliminating the factors that have caused it. This may include modifying equipment or training and/or identifying functional causes that contribute to the trauma. A stress fracture can be caused by something as simple as running on an old athletic shoe that no longer provides much shock absorption or playing tennis frequently on a hard surface (i.e., on asphalt rather than a composite surface). A limb-length discrepancy can lead to a stress fracture in someone who increases his/her level of intensity or runs on the same side of the road (causing one leg to be lower than the other as the feet slant with the crown of the road). Biomechanical imbalances can predispose an athlete to a stress fracture.

Stress fractures can be difficult to manage, especially in the competitive athlete. Failing to recognize the possibility of a stress fracture or to follow a supervised rehabilitation plan can seriously delay athletes’ return to competition and/or predispose them to future stress fractures.

Answer, provided by Kenneth Meisler, DPM, Executive Board AAPSM

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What is a "stress fracture" and how should it be treated?