Hairline Fracture

By Ehren Allen, Certified Manual Therapist/Physical Therapist

A hairline fracture, or stress fracture is a small crack or bruise in a bone.  The small microscopic cracks in the bone can get worse without some sort of intervention.  Hairline fractures of the wrist and hand are more common with a fall or accident.  However, these fractures are more common in the legs and feet. Impact activities or change in exercise activities can increase the chance of having a stress or hairline fracture. Osteoporosis may also increase the risk.  Low calcium or vitamin D can also be a contributing factor in the development of these fractures.  The most common hairline fracture is in the foot or metatarsal bones of the foot.

What Causes a Hairline or Stress Fracture?

Changing or increasing the load on bones is usually what causes a hairline fracture. Bones become stronger and weaker based on the demands and stress placed on them. Stress on a bone stimulates bone formation or osteogenesis. When minimal to no force is placed on a bone, the bone material begins to be reabsorbed and becomes weaker.

So, if you have led a sedentary lifestyle and decide to go out and run a 5K, the stress and load on the bones could cause this condition.  High impact sports can also lead to these fractures of the lower extremities.  Here is a list of sport with a higher risk of stress fractures:

  • Football
  • Soccer
  • Tennis (hard courts)
  • Running, Track & Field Events
  • Dancers
  • Basketball
  • Volleyball
Hairline Fracture Leg JOI Rehab

Image of a Hairline Fracture of the leg

Stress Fractures in Legs and Feet

The feet and lower legs are the most common places to have a stress fracture.  This is due to the load from body weight that they carry with daily activity. Running places up to 6x the normal body weight through the legs and feet with every stride. If the bones are not accustom to that activity, they can be prone to stress injuries.

Other causes for hairline or stress fractures in the feet include:

  • Changing shoes – This can alter the way your body absorbs stress through the legs and feet.
  • Blisters – Pain from a blister causes a change in walking or running patterns.  This can lead to excessive force on bones or the metatarsals of the foot.
  • Changing surfaces- Another cause can be changing the surfaces of your training or sport.  Changing from sand, clay and concreate can be a source of pain and stress.
  • Poor Bone Density or a Lack of Vitamin D and Calcium.
  • Flat Feet or Feet With High Arches.

Symptoms of a Hairline Fracture

There are 3 major symptoms of a Stress Fracture or Hairline fracture.

  1. Pain or tenderness to palpation over the bone
  2. Swelling or edema
  3. Bruising or discoloration

How do you Know if You Have a Stress Fracture?

The pain usually increases with stress or weight on the area.  The stress on the bone is usually a result of high impact activities like jumping or from overuse.  Bruising is typical and may spread to surrounding areas. Hairline fractures often cause swelling in the surrounding tissue.  Often, the patient will report a dull ache or pain in the bone.  It gradually gets worse if activities continue.  Most hairline fractures will heal with rest or immobilization of the body part.  However, if the repetitive activity or overuse of the body part continues, the fracture can progress.

If you notice these symptoms during or after an activity with no known incident, a stress fracture is possible.

Hairline Fracture Diagnosis

It is important to be properly evaluated by a physician if you think you have a stress fracture.  In this case, a doctor may order imaging or tests. The most common is an X-ray. X-rays can show variations in bone tissue and can usually determine whether there is a hairline or stress fracture.  Sometimes, other tests like an MRI, CT or Bone Scan may be other tests your MD may choose.


The initial treatment for a potential stress fractures is to rest and ice the area.  A physician may place you on crutches or immobilize the area with a brace or boot.

Click to learn the differences in X-ray vs. MRI vs. CT scan.

Related Articles: Hairline Fractures of the Arm, Wrist Hairline Fractures,  and Hand Fractures. 

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