Stress fractures occur from tiny cracks in the bones from repetitive activity, referred to as cumulative trauma. Usually, stress fractures occur in the tibial and metatarsal bones (see diagrams below), but they can occur in any weight-bearing bones. Stress fractures occur in people who undergo a great deal of physical activity, such as military personnel, athletes, and runners.
Stress fractures usually occur in weight-bearing bones, like the tibia and metatarsals (foot bones).
Stress fractures are a result of cumulative trauma from repetitive, overuse actions.
Stress fractures may not be visible on x-rays for two to four weeks after the pain starts; thus, a CT scan or MRI may be needed for diagnosis.
The initial treatment for a stress fracture first is to stop the repetitive activity that caused the fracture. Other treatments include ice, better footwear, braces, crutches, and surgery.
Our normal bone is constantly remodeling, which involves breakdown and reformation. With repeated and excessive strain, the bone is broken down faster than new bone can be formed, leading to a stress fracture.
Causes of stress fractures
Stress fractures are caused by repetitive trauma (cumulative trauma). When muscles become fatigued and overworked, they can no longer absorb shock, and the stress is transferred to the bones.
Stress fractures were initially described by a German military surgeon, Breithaupt, in 1855, years before the development of x-rays. Breithaupt described this condition in military recruits who did a lot of marching, especially those carrying heavy loads.
Common areas for a stress fracture
Even though a stress fracture can occur in any weight-bearing bone, it most frequently occurs at the tibia or a metatarsal bone (of the foot).
In addition, there are other weight-bearing areas for a stress fracture, including the fibula, femur, and pelvis.
Lastly, certain sports can lead to a stress fracture: a wrist bone (named the navicular or scaphoid) in a shot-put athlete, the ribs in a rowing athlete, and the lumbar (low back) vertebrae in a baseball pitcher.
Statistics show that 95% of stress fractures occur in a lower extremity due to the forces from weight-bearing activities, such as marching, walking, running, or jumping.
Factory workers are at high risk for a stress fracture of the wrist.
Risk factors for stress fractures
Regarding risk factors, there are extrinsic (outside forces) and intrinsic (our body) elements.
Extrinsic risk factors:
- Footwear. Especially footwear that is not fitted correctly or warn (old).
- Overtraining. Especially when starting a new activity.
- Posture. Bad posture when exercising.
- Surface. Running on an uneven or too firm of a surface.
- Diet. A poor diet with insufficient calcium or Vitamin D.
Intrinsic risk factors:
- Gender. Females are more at risk.
- Bone density. Low bone thickness (density) in conditions like osteoporosis.
- Growth. Especially abnormal leg lengths.
- Muscles. Insufficient muscle mass from poor levels of muscular conditioning.
- Feet. Having flat feet or high arches.
One additional risk factor for a stress fracture is non-steroidal anti-inflammatory medications. One study published in the journal Medical Surveillance Monthly Report (MSMR) found an increased risk of stress fractures in military personnel who had used NSAIDs, confirming the results of other studies on NSAIDs and stress fractures.
Diagnosing a stress fracture:
Diagnosing a stress fracture includes history, physical exam, laboratory tests, and imaging studies.
The history is essential to elicit some cumulative trauma from repetition along with the extrinsic and intrinsic risk factors mentioned above.
The pain from a stress fracture has the following characteristics:
- Pain that begins with the activity.
- Pain that occurs after the activity ends and becomes progressively worse.
- Pain the next morning after the activity.
The physical exam may demonstrate specific tenderness at the fracture site and be very sensitive to touch. In addition, swelling may be present.
Laboratory tests can check Vitamin D and calcium levels. In addition, thyroid laboratory tests should be done since high levels of thyroid production can lead to osteoporosis.
Plain x-rays are crucial for stress fracture evaluation and are easily accessible. However, one issue to consider is that stress fractures are frequently not visible on x-rays, called a false negative, since the x-ray may appear falsely negative (no fracture).
Stress fractures are often not visible on plain x-rays until two weeks after the pain starts and sometimes not until a month after the pain starts.
Further evaluation can be done with computed tomography (CT or CAT) or magnetic resonance imaging (MRI) scans. Both produce three-dimensional computer-generated images allowing the physician to visualize more bone detail than a plain x-ray. However, the MRI is the most specific and sensitive test for stress fractures and is considered the “gold standard.”
Treatment for stress fractures
Treatment for stress factors includes:
- Avoid activity. Cease the activity causing the stress fracture, like running, jumping, or marching. The activity should be avoided for two to six weeks and can be gradually resumed.
- Ice and elevate. This can reduce the pain and swelling.
- Supplements. If needed, add supplements, including calcium, Vitamin D, and thyroid.
- Footwear. Wear proper sneakers or shoes.
- Stop early or on time. Avoid overtraining.
- Cast. In some cases, a fitted cast is needed to keep the bones in proper position.
- Braces. In some cases, a brace, either soft or firm, can help.
- Crutches. Use these to limit weight bearing.
- Short-term NSAIDs. These are controversial since they help with swelling and pain, but they could inhibit healing.
- Surgery. This may be needed in some cases. A surgeon could attach a metal plate or screws.
If you exercise much, and feel pain at one specific area, stop the activity and see your physician for evaluation, even without any trauma.
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