Stress Fractures

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Stress fractures are common in athletics. Many medical professionals feel that stress fractures can be avoided if proper preventive steps are taken. If an athlete does suffer a stress fracture, early recognition and appropriate treatment will result in minimal time loss for the athlete.

Stress fractures are overuse injuries that can be caused by several factors. Most commonly a stress fracture is the result of a rapid acceleration in training intensity, abrupt change in training surfaces from soft to hard, improper or excessively worn equipment (i.e. worn out shoes), or increased physical stress (a basketball player going from limited minutes to a starting role).

Ninety-five percent of all stress fractures involve the lower extremities. The most commonly involved bones are the tibia and metatarsals. Other commonly involved bones include: the tarsals, calcaneus, fibula, femur, pelvis, sesamoids, and spine.

Athletes participating in tennis, track and field, gymnastics, and basketball are statistically more affected than other sport participants.

Stress fractures seem to be statistically more common in women than men; statistically reported to be 2% to 10% higher incidence in females. This may be due to the female-athletic-triad of eating disorders (bulimia or anorexia), amenorrhea (infrequent menstrual cycle), and osteoporosis.

Amenorrhea is thought to be a significant indicator for development of stress fractures. The incidence of amenorrhea in female athletes has been reported to be as high as 40%, compared to an incidence of 1% in the general population. Females have their peak bone density at 22 years of age; after 22, female bone density declines. Amenorrhea appears to be the leading indicator in premature osteoporosis in young females; inhibiting maximum bone density due to hormone level irregularities.

A stress fracture occurs when the forces acting a bone (either compressive, rotational, or tensile) exceed the strength of the bone. The applied stresses result in microfractures in the bone. This triggers the body’s healing process. The bone remodeling in response to the stressors activates both osteoclastic (bone resorption) and osteoblastic (bone production) cycles. If the stresses continue, the osteoclastic response out paces the osteoblastic response causing the weakened bone to more susceptible to fracture.

Evaluation

Early evaluation and diagnosis of stress fractures is important to help allay patient morbidity. Some stress fractures when ignored may need to be treated surgically to restore the athlete to full function.

Symptoms are nebulous and may only be present during or immediately after exercise. The athlete may describe diffuse pain in the affected area that resolved with stoppage of the activity but has progressively worsened over time. After a long period of time, the pain may never allay with rest. As the injury worsens, the pain may become more localized to the site of the fracture.

The physical exam should concentrate on determining the area of maximum point tenderness. If the affected area is swollen, point tender, or warm, a stress fracture should be suspected. Unfortunately, any or all of these symptoms may be absent, making a definitive diagnosis difficult. A tuning fork can also be used to help determine if a stress fracture is present.

Radiographic Findings

Plain film radiographs, especially early in the injury cycle, are often inconclusive. Due to this, if a stress fracture is suspected further imaging should be performed. If a plain film x-ray shows the “dreaded black line” (shown in x-ray #1) in the middle-third anterior cortex more aggressive treatment must be considered to avoid the stress fracture progressing to a transverse fracture of the tibia. The second x-ray shows a healed cortex fracture.

Most physicians will order the “gold standard” a technetium Tc 99m diphosphonate three-phase bone scan.

Bone scan images are taken in three phases. Phase one images are obtained immediately after the intravenous injection of the tracer isotope. Phase one images demonstrate perfusion in bone and soft tissues and may shown acute inflammation. Second phase images, taken one minute after IV injection, reflect the hyperemia (excess blood in the area) and capillary permeability of the bone. The third phase images, seen in this picture are taken 3 to 4 hours after IV administration and reflect about 50% absorption of the tracer into the bone matrix.

The third phase images are most often used to make the definitive diagnosis of a stress fracture. As the picture shows, the darkened area (arrow) is the site of the stress fracture.

Treatment

Stress fractures typically heal with rest. The athlete should be removed from their sport. If the athlete has pain with ambulation, crutches should be used until pain-free walking can be attained. Return to sports participation is allowed in 4 to 8 weeks.

If the “dreaded black line” is seen the athlete may be treated in a cast or walking boot. They should be non-weight bearing for 1 to 2 months and may return to sports in 2 to 3 months. If the fracture fails to heal, surgical treatment (intramedullary rod insertion) may be performed.

During the rest period, the athlete should continue to aerobically condition on a stationary bicycle. Weight lifting for upper body strength and contralateral leg strength is also appropriate.

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©2000 - 2009 David Edell

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Last Update for AthleticAdvisor.com: 10/24/2009 12:09:35 AM