This research aims to develop an optimal physiotherapy intervention for people with arthrofibrosis (stiffness due to scar tissue) after total knee replacement (TKR). We will develop an optimal intervention by conducting:

1. A review of the evidence to identify what components could be included in the intervention, how effective they are and what outcomes have been measured by the research.
2. Interviews with patients with arthrofibrosis to understand the impact it has on their life and what outcomes are important to them and interviews with healthcare professionals (HCPs) to understand their experiences of treating patients with arthrofibrosis.
3. A Delphi study with a larger group of HCPs and patients to reach a consensus on what the optimal intervention should include. This involves a series of anonymous voting on a range of items that have been generated by the group and the results of the evidence review.
4. A workshop with patients, HCPs and health-care commissioners to finalise the intervention. During the workshop we will present our findings and work in small groups to agree the intervention

Inclusion Criteria for Patients:

• adults (aged 18 and over) of any age who have undergone elective TKR with post- operative arthrofibrosis/stiffness who have undergone manipulation under anaesthetic (MUA) in the previous 24 months or are currently listed for a MUA.
• Ability to give informed consent

Exclusion Criteria:

• Patients with neurological or blood disorders

For HCP participants :

• at least 5 years of experience working with joint arthroplasty including the management of patients with arthrofibrosis or 3 years in the case of orthopaedic surgeons.

Patients who have had problematic stiffness following knee arthroplasty and healthcare professionals who manage patients with those conditions.