A Comparison of Patients Receiving a Unicompartmental Knee Replacement With Robotic Assistance or With Conventional Instrumentation

A Prospective, Multi-Centre, Randomised Controlled Study to Evaluate the Clinical, Health Economic and Patient Reported Outcomes Following Unicompartmental Knee Arthroplasty With a Robotic Assisted Technique

A unicompartmental (partial) knee replacement (UKR) is the removal of one part of the knee joint (a condyle), that has become damaged due to osteoarthritis, and replacing it with an artificial implant. The placement of these artificial implants and how they are aligned with each other is important because they can impact overall knee function and the long-term survival of the implant. A UKR is a highly effective, recognised procedure for patients with end-stage osteoarthritis affecting one compartment of the knee joint. The functional outcomes following UKA are at a minimum of equivalence to total knee arthroplasty procedures, with some recent literature demonstrating improved functional patient reported outcome scores.

There have been significant developments in knee replacement surgery over recent years. In particular, the introduction of robotic surgical systems, such as the NAVIO and CORI systems (Smith+Nephew Plc). These systems are hand-held devices which can support the surgeon with the knee replacement procedure, the systems are image-free and do not require the patient to undergo any scans (such as CT scans).

Comparisons of robotic systems to conventional instruments have demonstrated that robotic platforms produce fewer positioning errors in total knee replacement. This can result in more precise knee alignment and better outcomes following surgery. With both the NAVIO and CORI Surgical Systems there is a reduction in radiation exposure due to them being image-free.

At present, there is some evidence available for the long-term outcomes of knee replacement implanted using robotic assistance (i.e. 2-10 years) however this study is designed to look at the early outcomes following UKR. There is no literature to date to show that robotic-assisted UKR is superior to conventional methods, within the early post-operative period (up to 12 months).

This study is designed to show that the NAVIO/CORI surgical systems are better than conventional methods for UKR. The hypothesis is that they will be cost-effective, will reduce the time a patient spends in hospital following their surgery, will improve patient satisfaction during the early recovery period and will improve the patient's early post-operative mobility and function.

Inclusion Criteria:

• Subject must provide written informed consent
• Subject must be aged 18 years or older at the time of surgery
• Subject is listed for a primary unicompartmental knee replacement (UKR)
• The indication for the UKR is primary arthritis of the knee joint involving one compartment
• The subject agrees to give informed consent to participate in the study including consenting to any incidental findings being reported to their General Practioner (GP)
• The subject agrees to consent to and to follow the study visit schedule
• The subject plans to be available throughout the 1-year post-operative period
• Routine radiographic assessment is possible

Exclusion Criteria:

• The subject undergoes a robotic-assisted UKR on the index joint as a revision for a previously failed surgery, or there is a need for complex implants, or any other implant than a standard unicompartmental knee arthroplasty (UKA)
• Subject is listed for a simultaneous bilateral UKR
• Subject does not understand written or spoken English used in the informed consent form
• Subject has active infection or sepsis
• Subject is to have a Smith+Nephew Journey II UNI implanted by non-robotic conventional instrumentation
• Subject is not available throughout the 1-year post-operative period
• Subject, in the opinion of the investigator, has a neuromuscular disorder that prohibits control of the index joint
• Subject is undergoing the surgery as a private patient
• Patients who, in the opinion of the clinical staff, do not have capacity to give consent
• Women who are pregnant
• Subjects with a medical or physical condition that, in the opinion of the investigator, would preclude safe subject participation in the study