Knee replacement is a common operation for patients with osteoarthritis. It is a major operation with a long recovery period. Physiotherapy is an important part of the recovery process because it can help improve strength and movement in the replaced knee and allow people to gain the maximum benefit from the operation. However, not all hospitals offer physiotherapy to patients once they have been discharged after their knee replacement operation.

In this research study, we looked at whether it is helpful to offer exercise classes to patients following knee replacement. This was done using a research approach called a ‘randomised controlled trial’. We have already conducted a small version of the study first (a feasibility study) so we knew that patients were willing to take part and attend the exercise classes. The protocol for the ARENA study was published in Trials.

The main ARENA study started in 2015 and finished in 2018.  A total of 180 patients from two hospitals in Bristol took part. Half of people were chosen at random to receive ‘usual care’ where they were provided with a booklet about exercise and referred to outpatient physiotherapy on a needs basis e.g. if they have poor mobility. The other half of people were invited to attend exercise classes, in addition to receiving ‘usual care’.

The exercise classes took place every week for six weeks, starting at six weeks after knee replacement surgery. In the class, patients practiced task-related exercises such as walking, stair climbing, and kneeling. Each patient was also given two individualised exercises, designed by the physiotherapist, to help address specific goals important to the individual person. Patients were given written information and advice for continuing the exercises at home after they completed the classes.

We asked everyone in the study to complete questionnaires during the first year after surgery to see if the exercise classes improve people’s mobility. We also collected information to compare the cost of providing both treatments.

When we looked at the results, we found that patients who attended the exercise classes had better mobility at 3 months after surgery. By 12 months after surgery, people who attended the classes still had better mobility than people who had usual care, although the difference was small. Knee symptoms, general health, mood and satisfaction with surgery were also similar, although patients who attended the classes were more satisfied with their physiotherapy care. There were no safety issues with the classes. We have published the findings in Arthritis Care and Research and have made a video summary of the study. We are now currently looking at the results to see if the classes were good value for money.

The study team is led by Dr Vikki Wylde, working alongside Dr Neil Artz (University of West of England), Wendy Bertram (North Bristol NHS Trust), Andrew Beswick (University of ‌Bristol), Professor Ashley Blom (University of Bristol), Amanda Burston (University of Bristol), Professor Rachael Gooberman-Hill (University of Bristol), Dr Erik Lenguerrand (University of Bristol), Dr Elsa Marques (University of Bristol), Mr James Murray (North Bristol NHS Trust), Dr Emily Sanderson (University of Bristol) and Mr Tarique Parwez (Emersons Green Treatment Centre). 

The study was developed in collaboration with the University of Bristol’s Musculoskeletal Research Unit’s patient involvement group, PEP-R, and user involvement continued throughout the study. 

The ARENA study was funded by the National Institute of Health Research (NIHR) [Research for Patient Benefit (Grant Reference Number PB-PG-1013-32010)]. The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. 

For further information regarding the study please contact Dr Vikki Wylde, Chief Investigator (

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