|Wednesday, October 27
What exactly are stress fractures?
Dr. Ting: A stress fracture is a disruption in the normal architecture of the bone. It differs from an acute fracture in that the mechanism is due to repetitive, cyclic loading, with forces being lower than the force necessary to produce an acute fracture-- for example, running as opposed to getting hit by something. It's most commonly an overuse injury. The most common site is somewhere in the lower extremities.
In what sports are they most likely to occur?
Dr. Ting: The most common sports where we see them are those that require repetitive impact, primarily running and jumping sports. When you run, you create forces two to three times your body weight on your lower extremities. If you're running a marathon, you've subjected your feet and shins to tons and tons of force.
Any situation in which you're overloading one part of your body theoretically can cause a "stress fracture." Other sports in which stress fractures can occur in the upper extremities include gymnastics, where we see wrist and forearm stress fractures. Foot fractures are most common in track and field athletes.
Are some people predisposed to the injury?
Dr. Ting: It has definitely been shown that there are certain intrinsic factors that can lead to stress fractures. I was involved in a study that showed that distance runners are at risk if they have a problem with hyperpronation (the excessive turning-in of your foot). We took a group of distance runners with stress fractures and tried to find a common component. The one factor we came up with was that hyperpronation contributed to an increase in stress fractures to the foot. Other studies have identified a more rigid, high arch as a factor. Realistically I don't think there is any one thing across the board that predisposes. In women, osteoporosis can contribute, in which there is a loss of calcium and a weakening of bone. In younger women, eating disorders can cause metabolic problems and a subsequent weakening of the bone.
What are the primary risk factors?
Dr. Ting: Here's what recreational athletes need to be aware of:
Strength of muscles also plays a factor. Muscles help absorb shock; with fatigue and overuse, muscles weaken and lose their effect as shock absorbers. So strengthening muscles helps prevent injuries from impact.
What are the symptoms?
Dr. Ting: Probably the most common symptom is localized pain that worsens with weight-bearing activity. Tenderness and swelling often accompany the pain.
How are stress fractures diagnosed?
Dr. Ting: It's not always easy to diagnose this condition. X-rays of suspected stress fractures are commonly negative for many weeks, which can be confusing. If a stress fracture is suspected, a bone scan is done, wherein radioactive material is injected into the blood stream and accumulates at the suspected fracture site. This allows confirmation of a stress fracture sometimes long before you would see X-ray changes. That's because the disruption of the bone is at a microscopic or histologic level, unlike a visible crack in the bone.
How are stress fractures treated?
Dr. Ting: Since overuse causes the injury, rest is the most common treatment. The second level of treatment is non-weightbearing (crutches), and the third, immobilization, such as casting or splinting. It varies from site to site or bone to bone. Generally you're looking at a period of around six weeks of rest.
Of course, as with other bone and muscle injuries, symptoms can be relieved with ice and anti-inflammatory medication.
We try to get athletes to do cross-training, such as running in the pool. The key is to somehow unweight the extremity but at the same time maintain cardiovascular fitness. And you want to maintain the strength of the extremity to optimize recovery. Physical therapy, such as isometric muscle contractions and resistance training without loading the involved bone, is instituted to accelerate rehabilitation.
In the case of stress fractures of the tibia (shin bone) that don't heal, a rod is sometimes inserted in the center of the bone to provide stability. It acts as an internal splint and prevents recurrence. We also use electrical stimulation and ultrasound bone-growth stimulators to help heal them.
If the cause was metabolic, as in the case of bone weakness due to Vitamin D deficiency, then you address that deficiency.
How can stress fractures be prevented?
Dr. Ting: When you have early signs of pain that persists after a workout, competition or training session, pay attention to it and try to alleviate that either by resting, altering the surface or correcting shoe wear. Awareness that stress fractures can be associated with sudden increases in intensity of exercise is important. When the pain persists with normal activity or if you have any clinical signs like swelling, redness, and tenderness that seem to be more significant than your normal soreness, that's when to seek medical attention.
It's also important to know that especially in young athletes, bone infections and tumors can mimic the signs of a stress fracture. That's even more reason why symptoms such as these should definitely be followed up on with a medical professional.