The study aims to estimate VO2 max levels at pre- and post-operative timepoints before and after hip arthroplasty surgery, using non-exercise-based measurement methods.

This observational cohort study will measure an estimation of VO2 max prior to and following routine robotic arm assisted hip arthroplasty surgery, and examine its association with outcomes of recovery after surgery. Although VO2 max is usually measured using cardiopulmonary exercise testing, these tests are often unachievable for an elderly population with end stage hip osteoarthritis and in a lot of pain. For this reason, this study will estimate VO2 max using the Seismofit® System. This works by measuring vibrations arising from heart beats that are transmitted to the chest. The small Seismofit® device is battery powered, and uses Bluetooth to communicate the results to a smartphone app. The device is simply attached to the lower part of the participant's sternum using an adhesive patch and takes around 45 seconds to record the data.

The study will also assess recovery through measuring pain and functional ability via patient reported outcome measures (PROMs) and objective performance assessments. In addition, participants will be invited to wear activity monitors on their wrist prior to surgery, and for 12 weeks after surgery, to understand changes in physical activity and sleep patterns.

Patients undergoing a robot-assisted hip arthroplasty with Professor Middleton at the Nuffield Health Hospital will be invited to take part in the study by the clinical team at Nuffield, and will be given a patient information sheet. If they are interested in taking part in the study, they will be contacted by a member of the research team at BU and invited into ORI to give their informed consent. Once the participant has consented, they will undergo pre-surgery assessments. It is anticipated that it will take 12 months to recruit the 30 participants. Participants will then have follow-up study visits on Day-1 at Nuffield Hospital, and at 3-, 6-, and 12-weeks post-surgery at ORI. Data relating to surgery, discharge and medication will also be taken from routine data collected at Nuffield Hospital. Participants will continue to be followed up clinically as per standard care at Nuffield Hospital. Findings from this feasibility study will inform the design of future interventions to improve cardiovascular fitness in patients undergoing hip arthroplasty surgery.

Inclusion Criteria:

• Male and female ≥ 18 years;
• Undergoing total hip replacement at Nuffield Hospital;
• Voluntary written Informed Consent obtained;
• Participant able to complete study follow-up.

Exclusion Criteria:

• Requiring revision hip arthroplasty;
• Patients with implanted electronic equipment, such as a pacemaker;
• Women judged by the Investigator to be of childbearing potential who are pregnant, nursing, or planning to become pregnant, and those who do not agree to remain on an acceptable method of birth control throughout the entire study period;
• Unable to provide informed consent (insufficient English, lives overseas, unable to return easily).

Patients undergoing Robot Assisted Total Hip Replacement at the Nuffield Health