The word occult according to Webster’s dictionary means “secret or mysterious.” In orthopedics, the word occult aptly describes rare types of fractures that do not show up on x-rays. Occult fractures pose a particular danger to patients who are prescribed exercise or physical therapy as a remedy for pain.
An excellent example of the occult fracture can be seen in women who are avid distance runners. Distance running efficiency heavily favors a narrow pelvis. Most women have the unfortunate disadvantage of having a significantly broader pelvis than do men. A broader pelvis results in an increase in stress on the bones of the hip, knee, and foot. Women who train for marathons place a large amount of force on these bones, and the result can be “stress fracturing” of boney surfaces. A great visual analogy of a stress fracture is a glass windshield of a car that develops fissures from a rock striking it.
The fissuring of bone with an occult fracture is problematic, because if the fracture remains undiagnosed, the patient runs the risk of doing considerably more damage. In short, exercise and running are generally contraindicated with fractures.
If you are having sharp pain in a joint or bone from repetitive stress (running or exercising), stop the activity and see a doctor. If your pain does not respond to conservative management (light stretching, physical therapy, massage), it is worth asking your doctor if a more thorough diagnostic test is in order. MRIs for example show more detail than a typical x-ray does.
The remedy for an occult fracture is removal of weight bearing forces through the bone until healing occurs. Using crutches to de-weight one’s leg for a month or longer is not glamorous, but it is better than the alternative.