• Reference Number: HEY-827/2022
• Departments: Radiotherapy
• Last Updated: 31 May 2022

What is Heterotopic Ossification (HO)

It is the formation of bone outside of where it should be in the skeleton. Often it forms in soft tissues close to the skeleton.  This can lead to swelling in the areas affected, pain and limitation of movement if close to a joint.

No one knows the exact cause of heterotopic ossification (HO) but there are number of factors that increase the risk of it developing:

• Hip surgery or other joint surgery
• Long period of immobility
• Joint infection
• Trauma to muscle or soft tissue

About 1 in 3 patients who have a hip replacement or a severe fracture of the long bones of the leg will develop some heterotopic ossification though in most this will not cause symptoms.

Treatment

Treatment depends on the amount of extra bone formation and its location. It may involve physiotherapy, pain relief medication, anti-inflammatory drugs, surgery and occasionally radiotherapy.

Radiotherapy

Radiotherapy is a treatment using high energy X-rays to kill or suppress cells which are growing abnormally.  It is commonly used in cancer treatment but can be useful in non-cancer conditions such as HO to suppress the cells that make new bone.

It is known that if someone has already developed HO they are at risk of recurrence of the same problem with further surgery.  Therefore, surgery to remove the excess bone may not solve the problem on its own. Similarly, radiotherapy on its own will not get rid of bone that has already formed.

A combination of surgery and radiotherapy is therefore sometimes suggested, removing the excess bone at an operation and adding radiotherapy at the time of surgery to help stop the problem recurring in the future.

Who will explain the treatment to me?

Before you agree to any radiotherapy treatment the need for this should have been discussed with you by your orthopaedic surgeon. As a next step, you will be seen by an oncologist in the Queen’s Centre. Oncologists specialise in the treatment of cancer and are therefore experts in the use of radiotherapy. Please do not think that because you have an appointment with an oncologist that this means you have cancer. The radiotherapy and the risk/side effects will be explained and you will have the opportunity to ask questions. If you want to go ahead with the treatment you will be asked to sign a consent form.

How is radiotherapy given?

Radiotherapy for HO is given before your surgery, a few hours before the operation. Treatment is very similar to having an X-ray and will involve you lying still for a few minutes while the X-rays are given to the target area.  Treatment will be done in the Queen’s Centre at Castle Hill Hospital because this is where the specialist radiotherapy machines are.

Prior to having the radiotherapy, the treatment area will need to be marked precisely. This will be done using regular (lower energy) X-rays, in the treatment position, usually lying comfortably on your back.  Some marks will be put on your skin with a marker pen to ensure that you are in the correct position when you have your radiotherapy.

You will either have your treatment an hour or two after the area has been marked, or you will return to the department the next day before your operation. The precise timing depends on the time of your operation but we will let you know when your treatment is to take place.

Side Effects

Side effects from a single dose of radiotherapy are usually mild. Side effects do depend on the area being treated and will be discussed with you in detail before any treatment. Common side effects can include:

• Tiredness
• Skin redness (like mild sunburn)
• Feeling sick
• Loose bowel motions

If any of these side effects are experienced they are likely to be mild and last less than one week.

Long-term Risks

Any exposure to radiation may increase your risk of cancer in the future.  The risk is small and modern radiotherapy techniques allow for accurate treatment, minimising the dose to the rest of the body.  If you are concerned about your risk of developing a cancer, please discuss your concerns with the oncologist.

Radiation to the hip joint will also deliver a small dose of radiation to the testes and ovaries. For ladies before the menopause and men of any age, it is important to let the team treating you know if you have plans to have children in the future. The dose delivered should not affect the function of the testes or ovaries but caution may be required to avoid conception for a period after the radiotherapy.

Please also let the treatment team know if you have ever had radiotherapy to your pelvic area before. This could have been many years ago and will probably have been for a cancer such as cancer of the cervix, bladder, uterus (womb) or prostate.

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