Stress fracture

What is a stress fracture, and how common is it?

A stress fracture (also called a fatigue fracture or hairline fracture) is a small crack or break in a bone. It's caused by repeated loading that's too small to break normal bone in one go¹. It happens when the bone can't repair itself between loads, often after a rise in activity such as more running, gym classes or a more active job². It sits at the severe end of bone stress injuries, which range from early stress reactions to established fractures³.

Most stress fractures are in the lower limb. The tibia (shin bone) is the most common site, and the foot is the most reported region⁴. They're mainly reported in athletes and military recruits.

What causes a stress fracture, and who gets one?

Usually it's a mix of things. Sudden jumps in training volume, intensity or frequency, without enough recovery, are among the strongest and most consistently reported predictors³. Increasing activity too quickly, or doing the same activity again and again, can bring one on, and so can everyday use of a bone weakened by a condition such as osteoporosis⁵.

Bone density, muscle strength, nutrition, footwear and training load all play a part⁴. Female athletes with irregular periods, low body weight or disordered eating are at higher risk⁶. Runners whose heel tilts outwards (hindfoot eversion) and athletes with a pronounced high arch also have a higher risk. Orthoses or different footwear haven't been shown to prevent stress fractures, so don't rely on them alone⁷.

Most of what's known about risk comes from athletes and military recruits and shows links rather than proven causes. If you're an athlete with irregular or absent periods, low body weight or restrictive eating, it's worth raising with a health professional.

What does a stress fracture feel like, and how is it diagnosed?

The main symptom is pain, which usually increases with impact activities such as running or jumping and eases with rest⁵. It may start only during activity, then progress to pain after activity and eventually at rest⁸. There's often little bruising or swelling², though some people have swelling and warmth over the spot⁹.

Your history is the most important part of assessment: when it started, whether it's worse with activity, at rest or at night, and whether it disturbs your sleep¹⁰. A clinician will also examine the area, and scans are used to confirm the diagnosis, not replace it¹⁰. An X-ray is usually the first scan, but changes often show only 2–8 weeks after symptoms begin, so a normal early X-ray doesn't rule out a stress fracture⁴.

What helps first?

Low-risk stress fractures are generally managed without surgery⁹. That means stopping or cutting back the activity that brings on the pain, using pain relief if needed, then returning to activity gradually. A pharmacist can advise on pain relief such as paracetamol. Shin bone (tibia) stress fractures are usually tried without surgery first¹¹. For stress fractures of the great toe sesamoids (two small bones under the big toe joint) in athletes, care often includes activity changes, pain relief, orthotics and physiotherapy for 2–6 months¹².

Get the site and risk level checked before deciding on a boot, crutches or a gradual return, and ask whether yours is low-risk or high-risk. High-risk sites need more thorough assessment, and treatment often differs, including a long period without putting weight on the limb¹³.

What helps if that isn't enough?

If your pain hasn't settled after a proper period of first-line care, ask for a review rather than just resting for longer. A sports medicine doctor or an orthopaedic surgeon can advise on next steps.

Surgery is considered for selected cases: high-risk sites, fractures at risk of getting worse, and those still sore after a proper trial of care without surgery. For example, a stress fracture at the front of the shin bone may be considered for surgery if it's still sore after 3–6 months of non-surgical care¹¹. Fractures at the top of the thigh bone (femoral neck), the base of the fifth metatarsal (the outer long bone of the foot) and the navicular (a small bone in the arch) often need surgery⁷. Where the thigh bone has shifted out of place, delaying surgery raises the risk of serious complications¹⁴. Surgery has its own risks, so decide with your surgeon. Don't start medicines or other add-on treatments for a stress fracture without professional advice.

How long does it take to get better, and how can I stop it coming back?

The outlook depends mainly on the site. Low-risk fractures such as rib stress fractures have a favourable outlook with care that avoids surgery, with a gradual return to activity over about 4–8 weeks once the pain has gone¹. High-risk sites are more likely to fail to heal or to break completely⁹. A delayed diagnosis of a thigh bone (femoral neck) stress fracture is common and raises the chance the bone shifts out of place, which makes return to sport less likely¹⁴.

When you return, build up gradually, include recovery days, and don't go back to any activity that brings your symptoms back. Avoiding sudden jumps in training is a sensible way to lower the risk³. If you're an athlete, it's worth reviewing your training build-up, footwear and eating with your clinician or coach, including whether you're getting enough fuel for your training⁶.