COVID 19 resulted in cancellation of all elective surgery therefore we need to terminate the trial with 95 participants.

The purpose of ReHip2 is to explore the impact on function and quality of life in patients following Total Hip Replacement (THR). A randomised controlled trial will compare two different rehabilitation pathways following surgery (Routine care with precautions and Treatment group with no precautions). The proposal is to carry out the RCT with a minimum of 182 patients based in the UK.

Dislocation of the hip following total hip replacement (THR) is the sole reason for the endorsement of precautions following THR. This has remained unchanged sine the first hip replacement in 1969.

The precautions are;

• Patients must not bend past 90 degrees at the hip (including sitting)
• Patients must not twist in either standing or sitting
• Patients must partial weight bear with elbow crutches for a minimum of 6 weeks
• Patients must sleep on their back for a minimum of 6 weeks
• Patients must not cross their legs

Studies exploring factors affecting dislocation following THR identified three main influences: surgical technique, type of prosthesis and post-operative precautions. A number of studies have challenged the continued use of precautions or explored their impact on dislocation. However, these studies did not fully consider the impact of all precautions on dislocation, choosing to only select elements of the precautions for investigation. A recent review concluded the evidence evaluating practice and the impact of precautions was of poor quality. The review suggested further research should take into account different surgical approaches, different femoral head sizes and the type of prosthesis. Although there are studies that explored some of these hip dislocation confounders, the true impact of precautions remains unknown.

Whilst precautions continue to be endorsed by surgeons and other clinicians, previous challenges have raised awareness of the possible excessiveness of precautions and the importance of further robust work recommended. This is particularly so in the wake of developments in surgical technique and prostheses design, such as hip joint capsule repair and larger femoral head sizes (larger hip replacements). These developments and their impact on dislocation are beginning to cast doubt on the impact of post-operative precautions and their direct link to incidence of dislocation, which is their primary purpose.

The imposition of precautions has been evidenced to impact on both function and quality of life, with resultant non adherence in a proportion of patients. This study intends to explore whether an unrestricted pathway has no worse outcome in function, pain and quality of life parameters, in two specialist units in a multi-centre, prospective, randomised, non-inferiority study.

Inclusion Criteria:

• Adult participants over the age of 18 years will be included.
• All participants should be proceeding with routine care unilateral (one side only) primary THR for treatment of osteoarthritis
• The patients operating consultant agreed to involvement of their patients in the study.
• All subjects assessed during routine pre-operative assessment in their respective hospital will have been assigned an American Society of Anesthesiologists (ASA) up to grade 3 out of a total of 6 (defined as 'severe systemic disease that limits activity but is not incapacitating').
• Patients who have undergone previous hip injection for treatment of osteoarthritic symptoms.
• All surgical approaches (anterior, lateral and posterior), cemented and un-cemented prostheses and all size femoral head size.

Exclusion Criteria:

• The operating consultant declined participation in the study.
• The participant previously had hip surgery to the same hip, including arthroscopy, revision hip surgery or treatment for Avascular Necrosis.
• ASA grade 4 or above 'A patient with severe systemic disease that is a constant threat to life.'
• Patients with specifically identified increased risk of dislocation (for example neuromuscular disease, hypermobility)
• Complex primary hip replacement (THR with femoral osteotomy or structural bone grafting / augmentation of acetabulum)
• Patients unable to complete the postal outcome measures.
• Any patient with pre-operative cognitive impairment (Dementia or Learning disabilities).
• Patients undergoing THR for treatment of fractured neck of femur.