Bone cyst 



Bone is a hard, dense tissue that shows up clearly on X-rays, making them very useful for diagnosing bone-related problems

A bone cyst is a fluid-filled hole that develops inside a bone. They mostly occur in children and young adults.

Bone cysts do not usually cause any symptoms, they are not cancerous and they do not usually pose a serious threat to health.

However, larger cysts can cause a bone to weaken, making it more vulnerable to fracture. This can lead to symptoms such as pain, swelling or not being able to move or put weight on a body part.

Read more about the symptoms of bone cysts.

It is not known exactly what causes the build up of fluid that leads to a bone cyst, but several theories have been suggested, including damage to the blood vessels in the bone.

Read more about the causes of bone cysts.

Types of bone cysts

There are two main types of bone cysts.

Unicameral bone cysts

Unicameral bone cysts can develop anywhere in the body, although 90% of cases involve either the bone of the upper arm or the thigh bone. They often do not need treatment.

Most cases affect younger children between five and 15 years of age, with the average age at diagnosis being nine years. Boys are twice as likely to be affected by a unicameral bone cyst as girls.

Aneurysmal bone cyst

Aneurysmal bone cysts can also develop anywhere in the body. However, most cysts develop inside:

  • the bone of the thigh, lower leg or upper arm 
  • the vertebral bones (in the spine)

Aneurysmal bone cysts are thought to be very rare, affecting about one in every million people in any given year. They are not cancerous, but they can grow quickly and disrupt the normal workings of the affected bone.

Most cases of aneurysmal bone cysts affect young people who are between 10 and 20 years of age. It is thought that aneurysmal bone cysts are slightly more common in females.

Treating bone cysts

Most bone cysts heal within six months to a year without the need for treatment.

If a bone cyst does not get better, or if treatment is recommended to help reduce the risk of a fracture, several treatment options are available.

For example, steroids may be injected into the bone to encourage the cyst to heal. If the bone is still not healing, surgery may be needed to treat the cyst.

However, there is a one in three chance that a bone cyst will recur in the future, usually within two years.

Read more about how bone cysts are treated.

Page last reviewed: 20/11/2012

Next review due: 20/11/2014


How helpful is this page?

Average rating

Based on 61 ratings

All ratings

Add your rating


The 1 comments posted are personal views. Any information they give has not been checked and may not be accurate.

crys77 said on 29 March 2014

I am also well above the common age of a bone cyst, I am currently 37 & was about 34 when my symptoms started. According to the info provided I also believe I had an aneurysmal bone cyst that was removed/treated today. One big clue is I had steroid injections that helped me greatly but did not stop the symptoms. The surgeon drilled the cyst out, draining it and then fractured the area to promote blood flow and hopefully filling it in. I am now very interested in how many more adults are affected with this. I think having this info 4 years ago would have been very beneficial to my overall health and family. Wondering if there have been any studies done on adults or if anyone will be doing any studies on this? We may not be many in numbers , but the effects on my life and others is great! Dr's had not even looked in to this until yesterday and I had to travel to a top surgeon in the US! I am from the US.

Report this content as offensive or unsuitable

Child health 6-15

Information on child health, including healthy diet, fitness, sex education and exam stress

Find and choose services for Bone cyst