A stress fracture is a separation of the bone cells (osteons) that is sometimes seen on x-ray. This is not a type of fracture where the separation of cells is so wide that it might be called a "greenstick" fracture or that the bone alignment is disrupted.
Observation of a suspected stress fracture via x-ray, at times, does not occur until the fracture site is three weeks into its healing stage. If a stress fracture is suspected, a bone scan will rule it in or out. Stress fracture can occur to any bone. In the foot it usually involves the middle three metatarsals or the calcaneus (heel bone). In the leg, your long lasting "shin splints" may be a stress fracture of the tibia. The fibula (the bone next to the tibia in the lower leg) and the femur (thighbone) have been known to fatigue as have the pelvic bones.
The cause of bone fatigue usually involves one or more of the following:
- A repetitive, rhythmic motion (walking, running, marching)
- A rapid change in activity or training (so that the bone doesn't have time to change to the new forces acting upon it)
- A quick change in surfaces of the foot
- Poor mechanical structure causing areas of increased stress or shock.
Stress fractures hurt in the area localized to the injury. Pain can be acute in origin but usually occurs over a period of time. It may respond to rest but as soon as the fractured part is used, it begins to hurt (optimally, bones take 6 weeks to heal). Many times, if the subject bone is a metatarsal, a small red spot and/or swelling points out the fracture. As mentioned before, an x-ray or bone scan can be definitive.
The treatment usually involves some sort of immobilization of the affected part. This can range from taping, surgical shoe, walking boot, flexible cast or a rigid cast. All require a discontinuation of athletic activity as continued force on a stress fracture can cause a complete disruption of bone and possibly a dislocation of the fracture site. If a need to continue cardiovascular activity is present, swimming is recommended.
Most times stress fractures can be prevented if the most common causes are avoided. Make initiation of activities gradual and make change in training slowly. Change shoe gear as it wears out and pay attention to surfaces with more or less absorptive capability.