Potential subjects attending the initial appointment at 7-10 days in the outpatient physiotherapy department will be offered the full consent form. Those that do not attend or do not consent will be referred back to Accident and Emergency and return to usual care. Those that consent will be randomised into control or intervention group using a computerised random number generator. The control group will continue with maintenance exercises. Having a control group means that the intervention (imagined movements) can be isolated and tested with greater confidence. This helps to improve the quality of the study and this benefit to the study is believed to outweigh the small risk that having a control group would raise. By having the control group follow usual care as closely as possible further minimises ethical issues and potential risks. All efforts have been made to ensure this but it is recognised that all participants will need to attend two appointments that they would not normally attend on normal care. These are necessary to provide a cooling off period and collect data for the study.