Stress fractures are small incomplete fractures that often involve the metatarsal shafts. They are caused by repetitive weight-bearing stress.
Stress fractures do not usually result from a discrete injury (eg, fall, blow) but occur instead following repeated stress and overuse that exceeds the ability of the supporting muscles to absorb the stress. Stress fractures can involve the proximal femur, pelvis, or lower extremity. Over 50% involve the lower leg and, in particular, the metatarsal shafts of the foot. Proximal stress fractures suggest the presence of metabolic bone disease such as osteoporosis.
Metatarsal stress fractures (march fractures) usually occur in
Runners who too quickly change intensity of workouts, time of workouts, or both
Poorly conditioned people who walk long distances carrying a load (eg, newly recruited soldiers)
They most commonly occur in the 2nd metatarsal. Other risk factors include the following:
Cavus foot (a foot with a high arch)
Shoes with inadequate shock-absorbing qualities
Osteoporosis
Stress fractures also may be a sign of the female athlete triad (amenorrhea, eating disorder, and osteoporosis).
Symptoms and Signs of Stress Fractures
Forefoot pain that occurs after a long or intense workout, then disappears shortly after stopping exercise is the typical initial manifestation of a metatarsal stress fracture. With subsequent exercise, onset of pain is progressively earlier, and pain may become so severe that it prohibits exercise and persists even when patients are not bearing weight. Signs can include evidence of acute inflammation or only reproduction of the pain with regional pressure or foot squeeze.
Patients who have persistent deep groin or thigh pain with weight bearing must be evaluated for a proximal femur stress fracture. Patients with such fractures should be referred to a specialist.
Diagnosis of Stress Fractures
X-ray or bone scan
Standard x-rays are recommended but may be normal until a callus forms 2 to 3 weeks after the injury. Technetium diphosphonate bone scanning or MRI may be necessary for early diagnosis. Women with stress fractures of the proximal femur or pelvis may have undiagnosed osteopenia and may require additional testing (eg, dual-energy x-ray absorptiometry.)
Treatment of Stress Fractures
Restriction of weight-bearing activity
Treatment includes cessation of weight bearing, for example, on the involved foot (in case patients have a metatarsal stress fracture), and use of crutches. Although casting is sometimes used, a wooden shoe or other commercially available supportive shoe or boot is preferable to casting to avoid muscle atrophy. Healing can take anywhere from 6 to 12 weeks.
