What is a Stress Fracture?
A stress fracture is a small crack in a bone and is usually caused by overuse and repetitive activities. Sports that involve running, jumping, and quick change of direction have potential to cause stress fractures. The repetitive force creates microscopic damage to the bone that would typically heal when adequate recovery and nutrition are provided between bouts of activity. Even nonathletes that suddenly increase their amount of walking (as with military recruits or people on vacation) can develop stress fractures.
What Causes a Stress Fracture?
Typically, too much/too soon/not enough recovery causes stress fractures, but other factors can contribute.
Training errors: Stress fractures often are the result of increasing the amount and/or the intensity of the athlete’s training too quickly. Increases in training that should have taken months, instead happen over a few weeks. The metabolic capacity (fitness) improves faster than structural capacity (the bones and joints).
We normally associate stress fractures with athletes involved in training, but stress fractures do occur in previously inactive people that suddenly increase the amount of walking they do. This is often seen with military recruits when they first start basic training or people go on a vacation with lots of walking.
Equipment and biomechanical issues: Improper equipment (worn out shoes, shoes that are too stiff) can further increase these stress loads. Running with a heel strike style increases stress on the shins, femur, and hip. Excessive foot pronation and tight Achilles tendons add extra stress to the tibia.
Bone health issues: In addition, if over-all bone health (measured as bone density or bone mass) is suboptimal (osteopenia or osteoporosis), the bones have less ability to withstand the training stress and the risk of developing a stress fracture is increased. Chronic low energy (calories) intake can decrease bone health and combined with inadequate calcium and vitamin D intake can increase the risk if stress fractures.
Where Do Stress Fractures Occur?
Most stress fractures occur in the weight-bearing bones of the lower leg and feet. The femur and hip can also experience stress fractures, but these are less common than lower leg and foot fractures. One of the most common sites for a stress fracture in athletes is the 5th metatarsal otherwise known as a Jones fracture.
Suboptimal bone health (decreased overall bone mass) may contribute to developing stress fractures in the femur and hip. With further degradation of overall bone health, stress fractures may even be seen in ribs and vertebrae.
Are Women More Susceptible to Stress Fractures Than Men?
RED-S can increase risk in women more so than in men. Female athletes experience more stress fractures than their male counterparts. This may be linked to the RED-S (Relative Energy Deficiency in Sport) syndrome. The primary component of RED-S is low energy availability (EA). EA refers to the amount of energy available for normal physiologic processes, after the demands of training are met. Women with history of amenorrhea may have decreased bone mass and have a higher risk of stress fractures even if training loads are not too excessive.
However, men and women off all ages who participate in repetitive sports like running can develop stress fractures. Athletes of either gender with normal bone health can develop stress fractures when training volume and/or intensity are increased too quickly, and inadequate recovery is provided.
How Can I Ensure Long-Term Bone Health?
There are two main points concerning bone health:
First, 90% of peak bone mass is achieved by age 20 and reaching maximum values by age 30. The goal becomes to minimize the age-related decline in bone mass as we get older. And second, research suggests that it is very difficult to generate a significant and sustained osteogenic stimulus that can improve bone health to offset age-related bone loss. The bone mass you develop early (up until age 30 or so) is the bone mass you must live off as you get older. Unfortunately, young athletes may sacrifice their bone health while in high school or college believing the misconception that they can restore bone health once the athletic career is over. Female athletes who have a history of multiple stress fractures in high school and college, may be at high-risk for developing osteoporosis at a relatively young age.
What are Stress Fracture Symptoms?
Pain (for example, in the middle of the foot, along the inside of the shin above the ankle, thigh pain or groin pain) with activity is the most common complaint with a stress fracture. At first, the pain subsides with rest. If untreated, pain is felt even at rest. When the symptoms first appear, the pain may feel more diffuse and as the injury progresses the pain becomes more localized and point tender. With metatarsal stress fractures, swelling on the upper surface of the feet may be present as well.
Stress fractures happen over time giving advanced notice of the injury. It is important to listen to your body and deal with the injury early rather than later.
What Happens During the Physical Examination?
During the medical exam, the doctor will evaluate the patient’s risk factors for a stress fracture. This includes how long the pain has been present, training history before and after pain arose, status of shoes, menstrual history, history of previous stress fractures, and a brief nutrition assessment. A blood work-up may show elevated calcium levels due to an overactive parathyroid gland, placing the individual at increased risk of osteoporosis.
X-rays are usually taken to look for a stress fracture. The stress fracture starts as a small crack and can be hard to see initially. The fracture is more visible once it starts to heal, then the healing bone (callus) can be seen on x-ray.
Bone scans or MRI scan are more sensitive than x-rays for detecting stress fractures and may be used to get an earlier diagnosis (rather than waiting for the healing fracture to be seen on x-ray). These imaging tests can also help determine the severity of the injury.
What is the Treatment?
The most important treatment is rest. Athletes need to rest from the activity that caused the stress fracture. Most stress fractures will heal in 6 to 8 weeks. During this time, cycling, swimming, pool running can be used to maintain fitness. It is important to follow your doctor’s recommendations. Returning to activities too soon can delay healing or create situations where the fracture will not heal on its own.
When your doctor allows low-impact activities, incline walking on a treadmill, using an elliptical machine, or running on an Alter-G treadmill can be used. Walking on a treadmill at 15% incline and 3.6 mph has the same aerobic cost as running on a flat surface at 9 min/mile pace.
Who is at High-Risk for Stress Fractures?
If a stress fracture goes unrecognized and the individual continues to stay active, the fracture can worsen, leading to a complete break. This can have serious consequences and requires urgent surgery. It is important to recognize a stress fracture early to prevent this from happening. While this is true for all stress fractures, stress fractures in the femur and femoral neck at the hip are especially high-risk for devastating outcomes if not treated early.
Is There Surgical Treatment?
Certain stress fractures may require surgery to heal properly. In most cases, this involves stabilizing the bones by inserting some type of fastener. Pins, screws and/or plates can be used to hold the bones together during the healing process. Stress fractures in the 5th metatarsal foot bone (outside toe) and in the navicular and talus bones in the ankle often require this internal fixation to heal correctly.
What is the “Dreaded Black Line”?
Stress fractures in the tibia that go untreated can develop in to the “dreaded black line” which is seen as a transverse fracture line across the entire shaft of the tibia. Fractures of the anterior cortex of the tibia have a high likelihood of delayed healing or a non-union. An intramedullary nail is inserted in the length of the tibia to stabilize the bone allowing it to heal.
How Can I Prevent Stress Fractures?
Part of the treatment plan is to try and prevent the injury from occurring in the future. About 60% of the people who get a stress fracture have had a previous stress fracture.
Training modifications: The athlete’s mantra: “Training makes me tired; recovery lets me get faster/stronger.” Without recovery, training adaptations are greatly diminished. Training modifications can help reduce the risk of stress fractures and can actually help make training more effective.
Plan to rest. It is important to build in recovery period (days, weeks, and even months) into the training schedule. On a weekly basis – use a schedule of hard day/easy day/easy day. On a monthly basis – after every 3 weeks of training, decrease training by 30% for a week.
Gradually increase running distance. Several options for this; best option depends on your goals.
Cross-train more often. Whether a dedicated runner or a recreational athlete, cross-training can help with recovery and improve overall fitness. Good options are cycling, hiking, elliptical training, incline walk on treadmill, and swimming.
Add strength training to your routine. Strength training can improve performance, decrease injuries, and increase bone density. Strength training provides many other health benefits as well.
Nutrition concerns: Part of the prevention plan should also look at the athlete’s nutrition status. Individuals may benefit from an analysis of their diet. Eat a healthy diet that includes a variety of foods that provide adequate energy intake to support a patient’s training program and other basic physiologic needs.
To help prevent RED-S syndrome consume adequate calorie intake to prevent issues from low energy availability. This means at least 30 kcal/kg lean mass/day up to 45 kcal/kg lean mass/day. A female endurance athlete who weighs 115 lb and is about 15% body fat would want to consume at least 1333-1998 kcal/day.
Select foods and supplements that provide adequate amounts of vitamin D (1000-2000 IU/day) and calcium (1000-1500 mg/day) These amounts can help reduce the risk of future stress injuries.
To set up an appointment for further evaluation, please call (208) 336-8250.