A hairline fracture, also known as a stress fracture, is a small crack or severe bruise within a bone. This injury is most common in athletes, especially athletes of sports that involve running and jumping. People with osteoporosis can also develop hairline fractures.
Hairline fractures are often caused by overuse or repetitive actions when microscopic damage is done to the bone over time. Not allowing yourself enough time to heal between activities is often a factor in the probability of getting this injury.
The bones of the foot and leg are especially prone to hairline fractures. These bones absorb a lot of stress during running and jumping. Within the foot, the second and third metatarsals are most commonly affected. This is because they’re thin bones and the point of impact when pushing off on your foot in order to run or jump. It’s also common to experience a hairline fracture in your:
- ankle bones
- navicular, a bone on the top of the midfoot
The most common symptom of a hairline fracture is pain. This pain can gradually get worse over time, especially if you don’t stop weight-bearing activity. Pain is usually worse during activity and lessens during rest. Other symptoms include:
Most hairline fractures are caused from either overuse or repetitive activity. An increase in either the duration or frequency of activity can result in a hairline fracture. This means that even if you are used to running, suddenly increasing either your distance or the number of times per week you run can cause this injury.
Another similar cause of a hairline fracture is changing the type of exercise you do. For example, if you’re an excellent swimmer, it’s still possible to sustain an injury from suddenly engaging in another intense activity like running, no matter how good of shape you may be in.
Bones adapt to increased forces put on them through various activities, where new bones form to replace old bone. This process is called remodeling. When the breakdown happens more rapidly than new bone can form, you increase your likelihood of a hairline fracture.
There are also a number of risk factors that increase your chances of getting a hairline fracture:
- Certain sports: Participants in high-impact sports, such as track and field, basketball, tennis, dance, ballet, long-distance runners, and gymnastics, increase their chances of getting a hairline fracture.
- Sex: Women, especially women with absent menstrual periods, are at increased risk of hairline fractures. In fact, female athletes may be at a greater risk because of a condition called the “female athlete triad.” This is where extreme dieting and exercise may result in eating disorders, menstrual dysfunction, and premature osteoporosis. As this develops, so does a female athlete’s chance of injury.
- Foot problems: Problematic footwear can cause injuries. So can high arches, rigid arches, or flat feet.
- Weakened bones: Conditions such as osteoporosis, or medications that affect bone density and strength, can cause hairline fractures even when performing normal, daily activities.
- Previous hairline fractures: Having one hairline fracture increases your chances of having another.
- Lack of nutrients: Lack of vitamin D or calcium can make your bones more susceptible to fracture. People with eating disorders are also at risk for this reason. Additionally, there can be a greater risk of this injury in the winter months when you may not be getting enough vitamin D.
- Improper technique: Blisters, bunions, and tendonitis can affect how you run, altering which bones are impacted by certain activities.
- Change in surface: Changes in playing surfaces can cause undue stress to the bones of the feet and legs. For example, a tennis player moving from a grass court to a hard court may develop injuries.
- Improper equipment: Poor running shoes can contribute to your likelihood of getting a hairline fracture.
If you believe you have a hairline fracture, it’s important to seek treatment from your doctor as soon as possible.
Your doctor will ask about your medical history and general health. They’ll also ask questions about your diet, medications, and other risk factors. Then, they may perform several exams, including:
- Physical examination: Your doctor will inspect the painful area. They’ll probably apply gentle pressure to see if it causes pain. Pain in response to pressure is often the key for your doctor to diagnose a hairline fracture.
- MRI: The best imaging test for determining hairline fractures is an MRI. This test uses magnets and radio waves to provide images of your bones. An MRI will determine a fracture before an X-ray can. It’ll do a better job of determining the type of fracture as well.
- X-ray: Hairline fractures often aren’t visible on X-rays immediately after the injury. The fracture may become visible a few weeks after the injury takes place, when a callus has formed around the healing area.
- Bone scan: A bone scan involves receiving a small dose of radioactive material through a vein. This substance accumulates in areas where bones are repairing. But because this test will indicate an increased blood supply to a particular area, it won’t specifically prove there’s a hairline fracture. It’s suggestive but not diagnostic of a hairline fracture, as other conditions can cause an abnormal bone scan.
Ignoring the pain caused by a hairline fracture can actually result in the bone breaking completely. Complete breaks will take longer to heal and involve more complicated treatments. It’s important to seek out help from your doctor and treat a hairline fracture as soon as possible.
If you suspect you have a hairline fracture, there are a number of first aid treatments you can perform before you go to the doctor.
Follow the RICE method:
Nonsteroidal anti-inflammatory drugs (NSAIDs) such as acetaminophen (Tylenol) and aspirin (Bayer) can help with pain and swelling.
It’s important to seek further treatment from your doctor if the pain becomes severe or doesn’t get better with rest. How your doctor chooses to treat you will depend on both the severity and location of your injury.
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Your doctor may recommend that you use crutches to keep weight off an injured foot or leg. You can also wear protective footwear or a cast.
Because it usually takes up to six to eight weeks to completely heal from a hairline fracture, it’s important to modify your activities during that time. Cycling and swimming are great alternatives to more high-impact exercises.
Some hairline fractures will require surgery, where bones are supported by the addition of a type of fastener using pins or screws to hold bones together during the healing process.
It’s important to avoid high-impact activities during the healing process. Returning to high-impact activities — especially the one that caused the injury in the first place — won’t only delay healing but increase the risk of a complete fracture in the bone.
Your doctor may advise taking another X-ray to ensure healing before allowing you to return to your previous activities. Even after the hairline fracture is healed, it’s important to gradually return to exercise.
In rare instances, hairline fractures won’t heal properly. This results in chronic, long-term pain. It’s important to talk to your doctor to prevent pain and worsening injuries.