A study comparing the use of wooden spatulas to the Therabite device for head and neck cancer patients who have mouth opening problems (Trismus Trial)

Cancer type:

Head and neck cancers
Mouth (oral) cancer




Phase 2

Both wooden spatulas and a device called Therabite are used to help people who aren’t able to fully open their mouths after radiotherapy. This study compared these 2 methods for people who had radiotherapy for mouth cancer and cancer where the mouth joins the throat (oropharyngeal cancer).

More about this trial

Some people find it difficult to open their mouth properly after radiotherapy. This is because the muscles used to open and close the mouth are affected by the radiotherapy. This is called trismus Open a glossary item.

Trismus can be treated by gently stretching the jaw muscles using wooden spatulas. The spatulas are placed in the mouth between the front teeth for a period of time each day. The jaw muscles are stretched by increasing the number of spatulas over time.

The Therabite device is another way to gently stretch the jaw muscles. It is a hand operated device that is put inside the mouth. 

Therabite device

For this study people used the Therabite device or wooden spatulas before radiotherapy started and continued during treatment. Because the researchers thought starting the exercises before radiotherapy would be beneficial.

The aim of this trial was to compare Therabite with wooden spatulas to find which:

  • was best to treat trismus 
  • improved quality of life Open a glossary item the most 
  • exercise routine people were most likely to follow 

Summary of results

This was a feasibility study. 71 people took part.

It was a randomised study. The people taking part were put into 1 of 2 groups by a computer. Neither they or their doctor could choose which group they were in. 

  • 37 people used the Therabite device
  • 34 people used the wooden spatulas.

study diagram

After 6 months of usage there was no significant difference in trismus between the 2 groups. The acceptability of the exercises was the same for both groups. 

There was also no significant difference in the number of times individuals from each group contacted health professionals such as their GP or a dietitian Open a glossary item  at the hospital.  

The study team also used telephone interviews to ask the people about any issues that occurred and how these could be improved. 

They said that the frequency of the exercises should be reduced from 5 times a day to 3 times. And that a break from the exercises of up to 6 weeks should be allowed when the side effects of radiotherapy are at their worst. 

The team concluded that: 

  • exercises during and after radiotherapy can improve trismus
  • both Therabite and wooden spatulas are acceptable to people
  • a break when the side effects of radiotherapy are worst should be allowed
  • regular contact with the participants is needed to encourage and support them 

We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item) but may not have been published in a medical journal.  The figures we quote above were provided by the research team. We have not analysed the data ourselves.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Professor Nick Slevin

Supported by

NIHR Clinical Research Network: Cancer
NIHR Research for Patient Benefit (RfPB) Programme
The Christie NHS Foundation Trust

If you have questions about the trial please contact our cancer information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Last reviewed:

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