Title: Explanatory comparative study of conventional Total Knee Arthroplasty versus Robotic assisted Bi-UniCompartmental Knee Arthroplasty
Funder: Chief Scientist Office, Scotland

Abstract: We hypothesise that with the use of Robotic Assistive technology, Bi-UniCompartmental Knee Arthroplasty (Bi-UCKA) is a safe and clinically effective surgical alternative to Total Knee Arthroplasty (TKA) that offers improved clinical, functional and knee kinematic outcome for patients with Osteoarthritis of the knee. TKA is used extensively as a treatment option for patients with disease of more than one compartment of the knee (and in some centres in the UK it is used as treatment option for patients with purely medial compartment disease). TKA surgery has proven to be successful at reducing pain in the majority of osteoarthritic patients, however studies consistently report 10-20% of patients who are unsatisfied or suffer chronic pain after TKA. TKA surgery involves removal of the anterior and often posterior cruciate ligaments which is associated with a loss in proprioception. The quadriceps tendon is incised and therefore damaged during surgery and this combined with limitations of the prosthesis design leads to sub-optimal gait patterns during even basic flat level walking. Instability of the knee is common after TKA which impacts on patients’ confidence in undertaking more demanding activities. In contrast Unicompartmental Knee Arthroplasty (UKA) offers functional advantages by retaining the cruciate ligaments leaving a more normal feeling knee with better gait, proprioception and function. However, UKA is only suitable for patients with disease that is limited to the medial compartment of the knee. Bi-UCKA surgery involves replacement of both the medial and lateral compartments of the knee with two individual Unicompartmental Knee Replacements positioned within the same joint. It is suitable for subjects who have both medial and lateral compartment osteoarthritis of the knee and who have intact cruciate ligaments. Although TKA has been demonstrated to show good long term implant survival and is successful in reducing pain, it has functional limitations in terms of knee kinematics, gait and knee proprioception. Bi-UCKA surgery offers the potential kinematic benefits of Unicompartmental Knee Surgery for patients with more extensive bi-compartment disease. Bi-UCKA surgery has been attempted by a few highly specialists centres before, however the complexity of the surgery has prevented wider uptake. We believe that the concept has considerable merit, provided that the surgery can be performed accurately with repeatable results. The introduction of Robotic Assistive Technology for UKA has permitted far more accurate bone resection and positioning of implants than can be achieved using traditional surgical instruments. Robotic Assistive Surgery also offers the ability to pre-operatively plan surgery using 3 dimensional computer models of the diseased joint. Robotic Assistive Technology can easily be adapted to perform Bi-UCKA surgery. We believe that the detailed planning, combined with the increased accuracy of implantation and repeatability afforded by Robotic Assistive Technology has the potential to make Bi-UCKA surgery a viable treatment option for a proportion of patients who would normally receive TKA. We estimate that around 20-30% of the 84,000 patients who currently receive TKA in the UK each year might be suitable for Bi-UCKA surgery. We will carry out an explanatory randomised controlled trial to compare a novel Robotic Assisted surgical technique (Bi-Unicompartmental Knee Arthroplasty) against a standard TKA. The study will provide evidence of early phase efficacy for Robotic Assisted Bi-UCKA and will determine mechanism of benefit for Robotic Assisted Bi-UCKA. Research Questions: 1. What are the biomechanical kinematic benefits of Robotic Assisted Bi-UCKA surgery compared to TKA? 2. Are improved knee kinematics and proprioception associated with better clinical and functional outcomes after surgery? 3. Is the revision rate after Robotic Assisted Bi-UCKA surgery comparable with TKA surgery? 4. Does Robotic Assistance facilitate accurate implantation and alignment of all 4 components of a Bi-UCKA? We will randomise 80 subjects, who have both medial and lateral Osteoarthritis of the knee, to receive either Robotic Assisted Bi-UCKA or TKA. Robotic Assisted Bi-UCKA will be carried out with the aid of the MAKO RIO (Robotic Interactive Orthopaedic) System. The MAKO system has been in use for Unicompartmental Knee Replacement surgery since 2004 and has the longest track record of any of the Robotic Assisted Knee Systems currently available. Surgery will be carried out by 3 surgeons at Glasgow Royal Infirmary who have extensive experience of surgical robotics, including use of the MAKO system. The primary outcome measure for the study will be the proportion of patients with a bi-phasic (normal) gait during level walking. Researchers assessing Gait (and other outcome measures) will be blinded to the intervention each patient has received. This single centre study will provide proof of principle for Robotic Assisted Bi-UCKA and establish mechanism of benefit and size of benefit for this novel surgical procedure. Patients will be followed up in clinic at 3 months, 1 year, 2 years, 5 years and 10 years post-operatively. In order to assess the primary outcome (Bi-Phasic Gait), full biomechanical analysis of Gait and Stair negotiation will be undertaken pre and post-operatively. Knee Kinematics in a range of functional activities of daily living will be determined for each subject. These assessments will be undertaken at the BioEngineering Unit at Strathclyde University under the supervision of Prof Philip Rowe. Secondary outcome measures will include: mechanical alignment of the knee, early post-operative clinical functional knee scores, range of motion, knee pain, complications related to surgery, quadriceps and hamstring strength, post-operative activity level and intensity. Pre-operatively and at 3 months post-operatively patients will have a CT scan of their knee. This will allow assessment of the accuracy of implant positioning and characterise the differences between the two different surgical philosophies. Statistical analysis and methodological support for the study will be provided by Prof Graeme MacLennan at the Centre for Healthcare Randomised Trials (CHaRT) at Aberdeen University.

Lay abstract: Osteoarthritis (OA) of the knee is a common condition that affects ~25% of the population over the age of 50. Surgical treatment options for OA are currently mainly limited to knee replacement surgery, with around 84,000 being carried out in the UK each year, a figure that has increased by 30% since 2005. There are currently two main forms of knee replacement (or Arthroplasty) used to treat OA. Unicompartmental Knee Arthroplasty (UKA) - used when only one side of the knee joint is diseased. This form of surgery removes minimal amounts of bone as it only replaces the damaged side of the joint, positioning small metal implants within the knee to cover the worn out portions on one side of the knee joint and leaving the opposite side of the joint intact. The knee ligaments are also left intact during UKA surgery thus facilitating good knee function after surgery and providing a relatively ‘normal’ feeling knee. UKA is suitable for 10-25% of patients with knee OA, but currently only around 10% of patients are offered this type of surgery due to the technically challenging nature of the surgery. The alternative to UKA is Total Knee Arthroplasty (TKA). During TKA surgery the whole knee joint is removed (i.e. full width and depth of the knee) and replaced by large metal implants placed over the cut ends of the tibia (shin bone) and femur (thigh bone). Some of the knee ligaments are removed and damage is often caused to the muscles and tendons at the front of the thigh. TKA patients have poorer patterns of gait (movement of the limbs, e.g. walking pattern) compared to UKA, which limits patients function, particularly for demanding activities and prevents participation in all but the most sedate sporting activities. TKA patients also have a less natural feeling knee and patients commonly report loss of proprioception (awareness of the joint) which can make activities such as driving or walking on uneven ground difficult. Although TKA surgery is very effective at reducing knee pain, patient surveys consistently show that a large proportion of patients are dissatisfied with the function of their knee. Approximately 10% of patients report being no better after TKA surgery and a further 10% are actually worse. Although UKA provides better knee function than TKA it is only suitable for patients with disease on one side of their knee joint, leaving TKA as currently the only alternative for patients with disease on both sides of the knee joint. UKA is a more technically difficult operation to perform. However, recently surgical robotic systems have been introduced to aid surgeons undertaking UKA. The current market leader with this technology is MAKO Surgical corp. Their system uses CT scans taken before surgery to create a 3D map of the diseased knee; surgeons then use the 3D map to plan exactly where implants should be positioned. A surgical robotic arm with a milling burr (similar in concept to a dentist drill) is then used to cut exact shapes in the diseased bone in which to fit the metal implants. The use of a burr rather than traditional saw allows minimal bone removal combined with the ability to cut complex shapes rather than just straight surfaces. The robotic arm is controlled by the surgeon, but the system has safeguards to prevent the surgeon burring bone that has not been planned pre-operatively. A natural extension of the UKA technique would be to use two UKA’s implanted at the same time on either side of the same knee joint - Bi-Unicompartmental Knee Arthroplasty (Bi-UCKA). This technique would allow surgeons to leave knee ligaments intact and replace only the worn parts of the joint rather than removing the whole knee joint as occurs with TKA. We believe that this surgical option would offer functional advantages for patients and give them a significantly more ‘normal’ feeling and acting knee. Bi-UCKA surgery is extremely challenging and the required degree of accuracy in implant placement is beyond that which is likely to be achieved by most surgeons with conventional instrumentation. However, we believe that the use of robotic surgical assistance can facilitate the level of accuracy required for successful Bi-UCKA surgery. We believe that the combination of Bi-UCKA surgery and Robotic Surgical Assistance can offer a new effective and reliable treatment option for a proportion of patients who would otherwise be faced with a functionally limited TKA. We estimate that 20-30% of patients that require Total Knee Arthroplasty surgery could benefit from Bi-UCKA. We propose to undertake a randomised controlled trial to compare Robotic Assisted Bi-UCKA with traditional TKA. The study will determine whether or not this novel form of Robotic surgery can produce a more ‘normal’ acting and feeling knee, allowing normal patterns of walking (gait) and therefore producing functional benefits for the patient. We will include 80 patients within this randomised study. After surgery, patients will undergo Gait (walking) Analysis at Strathclyde University to determine how normal their walking pattern and knee movement is. The study will provide evidence that Robotic Assisted Bi-UCKA is safe and will determine mechanism through which Bi-UCKA facilitates functional benefits for the patient. We will follow-up patients over a 10 year period monitoring safety and collecting data on patients function, activity, pain and satisfaction. We will also use post-operative CT scans to determine how accurately implants have been positioned in the knee. Our multi-disciplinary team consists of 3 surgeons from the Glasgow Royal Infirmary Orthopaedic Research Unit, Prof Philip Rowe from the Centre for Robotic Orthopaedic Surgery at the University of Strathclyde and Prof Graeme MacLennan from the Centre for Healthcare Randomised Trials (CHaRT) at the University of Aberdeen who has expertise in running complex interventional studies. The team at Glasgow Royal Infirmary are uniquely placed to carry out this study having used the market leading MAKO Robotic Surgical System for UKA surgery since 2009. We are currently undertaking the first randomised controlled trial using this robotic system in the world. The research team also have experience using the two competitor robotic systems that are currently available on the market.

Research activity codes: 5.4 SURGERY;6.4 SURGERY
Health categories: MUSCULOSKELETAL