What Is a Pathologic Fracture?

A pathologic fracture occurs when a bone breaks in an area that was already weakened by another disease. When the bone is weakened by some underlying medical condition, the individual becomes more susceptible to fracture. Causes of weakened bone include tumors, infection, and certain inherited bone disorders. However, these are just a few of the causes; there are dozens of other diseases and conditions that can lead to a pathologic fracture.

Man with cast on his arm sitting at dinning room table looking at a laptop
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When a fracture of the bone occurs, there may have been an injury, such as a fall, that normally wouldn’t cause a fracture, but in the weakened bone did lead to fracture. Or, when the bone is severely weakened, a fracture can occur with no obvious event taking place. Simply walking or getting up from a chair can lead to fracture when the bone is severely weakened.

Fractures of the bone come in many shapes and types. The reason a fracture is called pathologic is that the bone was weakened even before an injury occurred. Sometimes pathologic fractures are obvious, and other times it is not as clear that there was a problem preceding the injury.

How a Pathological Fracture Usually Occurs

Typically, when a person breaks a bone, it’s due to an aggressive act that involves a sudden impact. For instance, it’s not uncommon for a bone to break during an intense contact sport like football or hockey, during a car accident, or when falling accidentally.

A pathologic fracture is different in that it usually occurs during normal, routine activity. For example, it might happen while you’re brushing your teeth, taking a shower, or going to the grocery store. A bone cyst might grow to a significant size and affect a major portion of bone, and, eventually, the bone may no longer be able to support normal bodily function.

How to Know Whether You Have a Pathological Fracture

Since you often can’t see what’s going on underneath the skin when you experience an injury, it can be hard to know whether a bone break is causing you pain, and if so, which kind of bone break it is. Go see your healthcare provider for an evaluation to find out.

Symptoms of any kind of fracture might include pain that’s mild to severe, a limb that looks out of place, bruising, swelling, tenderness, numbness or tingling, and/or difficulty moving a limb. Your healthcare provider may recommend an X-ray to determine whether a bone is broken. 

How do you know whether the fracture is pathological or not? The bottom line: Any patient who experiences a fracture without an injury that would normally cause the bone to break should be suspected of having a pathologic fracture.

Figuring Out the Underlying Cause

Many tests can be performed to help determine the cause of a pathologic fracture. Some of these include:

  • Laboratory tests, including blood count analysis and calcium levels
  • Imaging tests, including bone scans and MRIs
  • Bone biopsy, in which a sample of the bone is obtained, either at the time of fracture repair or before—this test can be helpful when a tumor or infection is suspected as a cause

Treatment Plan

To treat the fracture, itself, you may need to wear a cast or splint. Sometimes you might need surgery to put in plates, pins, or screws to keep the bone in place. You may need to rest for a certain period of time and avoid doing certain activities that stress the area of the fracture.

If the fracture is pathological in nature, your healthcare provider will also want to treat the underlying cause of the bone break to help prevent it from happening again. Treatment of a pathologic fracture is highly dependent on the cause of the weakened bone. Some causes of a pathologic fracture may weaken the bone, but not alter the healing properties of the bone. On the other hand, some causes of a pathologic fracture may prevent normal healing of the bone. As a result, some pathologic fractures require the same treatment as a normal fracture, while others may require highly specialized care.

1 Source
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  1. Palmer W, Bancroft L, Bonar F, et al. Glossary of terms for musculoskeletal radiology. Skeletal Radiol. 2020;49(S1):1-33. doi:10.1007/s00256-020-03465-1

By Jonathan Cluett, MD
Jonathan Cluett, MD, is board-certified in orthopedic surgery. He served as assistant team physician to Chivas USA (Major League Soccer) and the United States men's and women's national soccer teams.