Define "stress fracture". How is a stress fracture treated in a normal person? What are the consequences of a stress fracture which is not treated? Why might a young woman with an eating disorder be at particular risk for a stress fracture?
A stress fracture occurs when a bone breaks microscopically after being subjected to repeated tensile or compressive stresses, ie cyclical loading, in which not one single load which would be large enough individually to cause the bone to fail. (A "normal host" is defined as a person who is not known to have an underlying disease that would cause abnormal bone fragility. ) That is, stress fracture is the granddaddy of "repetitive stress injuries".
Here is an image to keep in mind
As you know, bending a paperclip too much will break it. If a clip will break with 12 bends, at the 11th, it has a stress fracture.
A stress fracture is believed to develop with abrupt increase in the duration, intensity, or frequency of physical activity without adequate periods of rest.
Important risk factors for developing stress fractures include a history of prior stress fracture, low level of physical fitness, increasing volume and intensity of physical activity, female gender and menstrual irregularity, diet poor in calcium, poor bone health, and poor biomechanics.
A stress fracture is also called a "march fracture" as taking a 40 mile stroll with military gear on one's back is a nice way to cyclically overload the bones
A bone scan, shown on the right, can help demonstrate the injury, as only an overt break would be seen on plain films
MRI can also make the diagnosis,
In addition to the tibia, the feet (5th metatarsal especially) are commonly involved
Stress fracture is, fundamentally, an overuse injury and THE TREATMENT OF AN OVERUSE INJURY IS UNDERUSE . (That is, if the patient would only stop beating up the bone and just let it heal all will be well.)
(photo of patient being treated for a stress fracture)
Not listening to the instructions to stop is a sign of not being normal…If they don't listen, a stress fracture can lead to "real" (separated) fracture.
A stress fracture of the superior femoral neck, shown here, can be a real disaster if not healed, as the fracture can displace and disrupt the blood supply to the femoral head
By contrast, a stress fracture of the calcaneous, if it displaces, will collapse on itself and not separate
Women with eating disorders are at particularly high risk for stress fractures because they typically lack adipose (a chemical precusor for many hormones) and thus do not have proper estrogen levels. Because osteoclasts are estrogen sensitive, these women have imbalanced bone remodeling –more eating, less building—and bad bone.
Eating disorders are one third of the so-called female athlete triad (eating disorders, amenorrhea, and osteoporosis).