The ReStARt study (Reducing Stiffness After knee Replacement)


Although knee replacement surgery is successful for many people, a small portion of patients develop severe stiffness due to excessive scar tissue around the new joint. This complication can severely restrict the movement in the knee and affects everyday activities, limiting mobility and independence. Along with infection, severe stiffness is one of the most common reasons why a person is re-admitted to hospital following a knee replacement operation.

There are currently no high-quality guidelines on how to best treat stiffness following knee replacement. Physiotherapy is the first recommended treatment, but it is unclear what this should include or how effective it is, and there is wide variation in how it is carried out by healthcare professionals. There has been some research into the types of physiotherapy that are suitable such as exercise, the use of devices to stretch the knee joint and education to the person before they undergo knee surgery. However, these research studies tend to be lower quality and involve smaller numbers of people, which means that the findings are limited.

People whose stiffness fails to improve with physiotherapy are usually referred for manipulation under anaesthetic (MUA), which is a procedure where surgeons put the person under anaesthetic and ‘manipulate’ or move the knee joint in order to loosen it and reduce pain and stiffness. This requires an additional stay in hospital and further intensive rehabilitation.

MUA presents additional risks for patients and can lead to further complications. People who undergo a MUA are more likely to need a new knee replacement in the future, which not only causes further inconvenience to patients, but is also costly for the NHS. Research has also shown that younger patients are at greater risk of severe stiffness in the knee. For people of a working age, the impact and burden are likely to be higher on the individual, on society and more costly to the NHS in terms of repeated MUA and further surgery.

Aims and Objectives

This aim of this research is to develop an intervention suitable for patients with knee stiffness following knee replacement that can then be tested in a bigger research study. The intervention will endeavour to improve outcomes for patients and reduce the need for MUA and further surgery. It will be developed closely with patients and healthcare professionals (HCPs) to ensure that we capture the needs and identify what issues are important for patients, make sure that the intervention is acceptable to patients, and confirm that it can be delivered well by healthcare professionals in the NHS. Four work packages will be undertaken as guided by the MRC framework for intervention development.


This study will be divided into 4 work packages:

  1. A systematic review to review the research evidence
  2. Interviews with patients and Healthcare Professionals (HCPs) to better understand the problem faced by patients, and experiences around treating this complication
  3. A survey with a larger group of patients and HCPs to agree what should be included in the intervention
  4. A workshop to finalise the details of how the intervention should be delivered.

The methods have been developed to ensure that the voices and needs of patients and the experiences of HCPs in delivering healthcare in the NHS are taken into account when developing this intervention. By doing this, our intervention should be acceptable to patients, suitable to deliver in the NHS, and can eventually be tested out in a bigger research study.

Study timeline

The research study will last for 18 months. Work packages 1 to 2 will be completed in the Year 1. Work packages 3 to 4 will be completed in Year 2.

Study funder

This research study is funded by the National Institute for Health and Care Research, Research for Patient Benefit funding stream.

Ethical Approval

This study has been reviewed and given favourable opinion by the East of England - Cambridge South Research Ethics Committee (22/EE/0205).

Get involved!

Patients who have had severe stiffness following total knee replacement

We want to include people who have undergone a total knee replacement and who have either gone on to have a MUA procedure or are due to have one done to take part in work-packages 2 to 4. If you are patient interested in taking part, please download the following information pack for more details about what is involved:

ReStARt study information for Patients document download

Patients can express an interest in participating by completing our online patient reply form: Patient reply form

Healthcare Professionals with experience of managing patients with severe stiffness following total knee replacement

We are also interested in involving healthcare professionals in work packages 2 to 4. If you have experience of managing patients with severe stiffness following total knee replacement surgery, please download the following information pack if you would like to find out more about getting involved:

ReStARt study information for Healthcare Professionals document download

Healthcare Professionals can express an interest in participating by completing our online HCP reply form: Healthcare Professionals reply form

Contact the research team

Dr Michelle Hall

Dr Michelle Hall

Room B317, School of Health Sciences, Nottingham University Hospital, NG7 2HA

Telephone: 0115 82 31794*




Dr Melanie Narayanasamy

Dr Melanie Narayanasamy

Room B302, School of Health Sciences, Nottingham University Hospital, NG7 2HA

Telephone: 0115 82 30940*





*These telephone lines are not monitored 24/7, so if we are unable to take your call, please leave a message, and we will get back to you as soon as possible.

Rehabilitation Research Group

The University of Nottingham
School of Health Sciences
Queen's Medical Centre
Nottingham, NG7 2HA

telephone: +44 (0)115 823 0843