An Evaluation of Health Outcomes for Mako Hip Replacement

This is an observational cohort study. It evaluates the recovery of 200 patients who are having routine robotic hip replacement surgery at a Nuffield Hospital in Bournemouth. Any complications from the surgery, or readmissions to hospital, will be reported. Investigators will measure how accurately the surgeon, assisted by the robotic-arm, positions the hip implant during the surgery using x-rays taken as part of routine care. The study also monitors the progress of rehabilitation by assessing pain and functional ability in the year following surgery, and will investigate whether there is an association between this recovery and a measurement of an area of muscle in the pelvic region, taken from a routine CT scan.

Patients will be asked to come to the Orthopaedic Research Institute at Bournemouth University to be assessed before they have surgery, and again at 3 weeks, 6-8 weeks, 3 months, 6 months and 12 months following surgery. At these visits they will be asked about their pain, how well they can do daily activities, and their quality of life. They will be assessed on their ability to sit-to-stand five times, walk for 40m, and climb some stairs. At each visit, except the three weeks visit, they will also have their gait tested on a specialised clinical treadmill, and the muscle strength in their legs measured. They will also be measured for oedema at baseline, 3 weeks and 6-8 weeks using a Fit3D ProScanner. These visits are in addition to the routine clinical follow-up visits at Nuffield Hospital. Participants will also be invited to wear a wrist activity monitor for at least three consecutive days prior to surgery and for the 6 weeks following discharge so that their activity can be recorded.

Surgery-related resource use of the procedure will also be reported, such as length of hospital stay, time in theatre, unplanned hospital visits, non-routine medication, outpatient appointments and physiotherapy appointments.

Inclusion criteria

• Non-inflammatory degenerative joint disease including osteoarthritis and avascular necrosis, suitable for unilateral primary hip replacement;
• Rheumatoid arthritis;
• Correction of functional deformity;
• Voluntary written Informed Consent obtained.
• Participant able to complete study follow-up.

Exclusion criteria

• Prospect for recovery to independent mobility compromised by known coexistent medical problems;
• Requiring revision hip replacement;
• Previous hip replacement (resurfacing or THR) on the contralateral side, with outcome achieving an Oxford Hip score <18 points;
• Likely post-operative leg length inequality >5cm;
• Neuromuscular disease affecting hip (Parkinson's, cerebral palsy, other spasticity);
• Primary or metastatic tumor involving this hip;
• Loss of abductor musculature, poor bone stock, or poor skin coverage around the hip joint;
• Previous arthrodesis or excision arthroplasty
• Acetabular deficiency - >2cm superior loss acetabular dome or >1.5cm protrusion acetabulae or wall deficiency> half a wall;
• Dysplasia (DDH) with >2.5cm subluxation or complete dislocation;
• Body mass index > 40kg/m2;
• Active or previous or suspected infection in this hip;
• Sepsis or osteomyelitis;
• Known sensitivity to device materials;
• Not physically able to use Grail gait lab and Primus muscle testing equipment;
• 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, cognitive disorder such as dementia, psychiatric illness);
• Unable to complete follow-ups (life expectancy <5 years, insufficient English, lives overseas, unable to return easily).