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Stress Fractures

Stress Fractures are common overuse injuries of bone resulting from the repeated application of a sub maximal load. These injuries occur mostly in runners, particularly in the tibia due to the bone not been able to handle the repetitive load.

When a load is put through the leg via ground reaction forces (landing on the ground) it causes microdamage to the bone. Normally the body then repairs and remodels the bone to strengthen it. Stress fractures occur when the bone does not have enough time to repair itself and this micro damage accumulates over time to form a "crack".

Prevention.

Studies have found that the major risk factors for stress fractures are; low bone density, abnormal muscle function, diet, menstrual disturbances, footwear and, a previous fracture and overtraining. So the best prevention is to manage these factors.

Things to be aware of when training to minimize the risk of getting stress fractures are:

• Type of training; reducing the amount of high impact exercises like jumping
• Surface in which you are running on; obviously the softer the better
• Volume of training; as this is a repetitive based injury this is the major cause. So decrease the volume.
• Type of shoe; use of a running shoe that fits.
• Age of shoe; shoes lose the ability to absorb shock.
• Strength, endurance and flexibility; by increasing these in leg muscles, particularly the calves.
• Studies show that females that have amenorrhea are more likely to get stress fractures.
• Calcium; Diet with sufficient calcium, although some foods such as chocolate, coffee and spinach inhibit the absorption of calcium.
• Energy; enough energy to help body with repair process.

Diagnosis.

Stress Fractures are typically diagnosed clinically. An X-ray is used to determine if the patient has a stress fracture, although this may fail to see a fracture. In this instance, if a stress fracture is still suspected a scinitgraphy is used. This is a very sensitive examination and will show a localized ‘hot spot" that indicates a stress fracture. This then indicates the severity and the location of the fracture.

X-ray images of stress fractures of the Tibia.

Treatment.

Rest.

The most important part of treatment for stress fractures is allowing the bone to heal its self through rest. Most heal without complication and training is back to normal after 4-8 weeks. The first part of treatment involves relieving pain and reducing swelling. This is done by using ice for the swelling and mild analgesics for the pain. In some cases it is painful for patients to walk, 2 crutches are used to limit the amount of weight bearing on the affected leg. This is in extreme cases and simply avoiding the aggravating exercise should be sufficient.

Maintainence.

Maintaining the athletes' strength and fitness is the next priority. To do this exercises must use large muscle masses but not over load the bone. Common exercises include cycling, swimming, water running and rowing. These exercises should be as close to athletes training program in both duration and intensity.

Resumption of Impact loading activities.

Resumption of training can begin when normal, day-to-day ambulation is pain free. The rate in which resumption takes place varies between individuals and is based on their symptoms and physical findings. Due to the weakness of the bone (due to the heeling process) a progressive overload approach is taken to gradually strengthen the bone. A graduated sequence would start off with low impact exercises such as cycling or under water running (part of the maintaining fitness stage). This can then be followed by walking, squats and stepper. Once these exercises become pain free, jogging on the treadmill is allowed then outdoor running in a straight line, followed by zig zag running and up or down hills. The last progression is high impact exercises like jumping or bounding. These should only progress when the exercise can be done pain free.

The rate of this progression is as follows:

• Brisk walk of 10 min, increasing 5 min per day until 45 min is achieved pain free.
• Once pain free; 5 minutes of the 45 minute walk can be a slow jog.
• Increase slow jog by 5 minutes each session until 45 minutes of slow jogging is achieved.
• Once 45 minutes of slow jogging is achieved the pace can then be gradually increased.
• Once full speed is achieved high impact activities such as jumping can begin.

If any bony pain is felt through this progression then 1-2 days rest is prescribed. The athlete should then resume training at volume and intensity below the level in which pain occurred.