Background Hip fracture affects 70,000 people in the United Kingdom (UK) and costs an estimated £1.1 billion per year to the National Health Service (NHS). Key clinical indicators, such as early surgical repair, have been shown to improve patient outcomes, however morbidity and mortality remain extremely high, reflecting the urgent need for novel therapies to enhance outcomes. Common complications include infection, cardiovascular events, falls and venous thromboembolism. Remote Ischaemic Conditioning (RIC) is a treatment whereby a blood pressure cuff is inflated around an arm or leg to above systolic pressures to occlude blood flow to the limb for short periods of time, that do not result in harm, but trigger innate mechanisms that reduce inflammation, improve organ blood flow and improve bone healing. These may be beneficial effects after hip fracture.

Methods This is a single centre, feasibility study; the participants will receive RIC daily for 40 minutes for 10 days during their inpatient stay. Outcome measures relating primarily to safety, tolerability and feasibility will be collected along with compliance with the intervention. Study feasibility will be determined by success criteria based on recruitment, outcome measure assessment compliance with intervention and follow up.

Secondary outcomes including inpatient mortality, inpatient complications, length of inpatient stay, blood pressure, serum inflammatory and stress markers and functional recovery will also be collected at discharge and 3 month follow up.

Results Data collected on safety, tolerability, and feasibility will be presented descriptively and simple analysis of variance will be undertaken on quantitative data such as blood pressure and serum inflammatory and stress markers between baseline and follow up time points. The study will hopefully establish whether this therapy is feasible to deliver after acute hip fracture.

This is a single centre, single arm feasibility study. The team will aim to recruit 12 participants to complete a programme of RIC for up to 2 weeks following hip fracture or until discharge from hospital or rehabilitation centre.

It is not known whether the main potential protective events resulting from RIC occur due to the short-term effects (likely changes in vascular sensitivity, blood flow etc) or the longer-term effects (modulation of inflammation etc that occur through changes in gene expression). However, the team have chosen a dosing strategy that they feel is practical to deliver given the average length of time people spend in hospital after hip fracture.

Inclusion Criteria:

• Adults (aged > 18 years)
• Participant has had a hip fracture identified on X-ray or computed tomography (CT) scan.
• Qualifying hip fracture has not occurred more than 7 days prior to enrollment.
• Able to give written informed consent.
• In the opinion of the treating physician would be able to conform to the study protocol and procedures.

Exclusion Criteria:

• History or presence of significant peripheral vascular disease in the limb conditioned.
• History or presence of complex neuropathic pains or peripheral neuropathy in the limb conditioned.
• Presence of lymphoedema in the limb conditioned.
• Presence of skin ulceration to the limb conditioned.
• Uncontrolled arrhythmia, hypertension, diabetes or angina.
• Third degree heart block or progressive heart failure.
• Acute aortic dissection, myocarditis, or pericarditis.
• Acute deep vein thrombosis, pulmonary embolism.
• Suspected or known dissecting aneurysm.
• Stroke or TIA myocardial infarction in the last 4 weeks.