Robot-Assisted Partial Knee Replacement Versus Standard Total Knee Replacement (RoboKnees)

Robot-Assisted Partial Knee Replacement Versus Standard Total Knee Replacement: A Pilot Randomized Controlled Trial

St. Joseph's Healthcare Hamilton, Hamilton Academic Health Sciences Organization, Canadian Institutes of Health Research (CIHR)

This is a pilot randomized trial to assess the feasibility of a definitive trial to determine the effect of robot-assisted partial knee replacements versus standard total knee replacements.

Knee osteoarthritis (OA) pain is an important source of morbidity and cost to the health care system. Over 60,000 knee replacement surgeries are performed in Canada every year, making it the second most common surgery. Our institution (St. Joseph's Healthcare Hamilton) is the first hospital in Canada to purchase a Mako RIO orthopaedic robot to assist with performing knee replacements. The knee is divided into three compartments, and one, two, or all three compartments can become arthritic. Over 90% of patients with end-stage knee OA receive a total knee replacement (also known as total knee arthroplasty or TKA) even if they have one or two healthy knee compartments. Partial knee replacements are an option for these patients but these procedures are very technically demanding and associated with a higher risk of implant failure. For this reason, few surgeons are experts at partial knee replacements. We believe that we can use robotic technology to make it easier for surgeons to perform partial replacements more accurately, thereby increasing the quality and survivorship of partial knee replacements. This may lead to better patient-important outcomes like return to activity, pain, and satisfaction, and eventually better access to high-quality partial knee replacements for Canadians. This will be the first study to evaluate total knee replacements (standard care) versus robot-assisted partial knee replacements, and could lead to greater uptake of robotic technology in orthopaedics and a shift toward anatomy-sparing partial knee replacements.

Total knee arthroplasty, Unicompartmental knee arthroplasty, Robot-assisted surgery, Pilot randomized controlled trial, Bicompartmental knee arthroplasty, Mako partial knee

Surgeons cannot be blinded to treatment group. It would not be feasible to blind the health care team and patients because the incisions and imaging are visually distinguishable. We will attempt to minimize bias in subjective measures by presenting patients with balanced information on each treatment group prior to the trial. All participants will receive a computed tomography (CT) scan prior to surgery to maintain blinding and to give surgeons additional information about 3 dimensional modelling for implant placement. Data analysts will be blinded to treatment allocation. An independent outcomes assessor will independently review radiographic alignment for each patient and review relatedness of adverse events and re-operations. The independent assessor cannot be blinded because imaging is visually distinguishable.

Participants who are randomized to the control group will undergo TKA according to local standard of care. The choice of implant and use of bone cement will be recorded but left to the surgeon's discretion according to their standard practice.

Participants with isolated medial or isolated lateral compartment OA who are randomized to the intervention group and have one affected knee compartment will receive a robot-assisted unicompartmental knee arthroplasty (UKA). If the patient has medial or lateral OA plus patellofemoral OA they will receive a bicompartmental knee arthroplasty (BiKA) consisting of a two simultaneous UKAs. The partial knee replacement procedures will be performed using the Mako RIO robotic arm (Stryker) according to the manufacturer's instructions. The choice of implant and use of bone cement will be recorded but will be left to the surgeon's discretion. Surgeons will resurface the patella if the patellar cartilage meets Outerbridge grade 3 or 4 criteria

Surgeon will perform a robot-assisted unicompartmental or bicompartmental knee arthroplasty procedure

We will use the 5-item Return To Function (RTF) questionnaire to determine when a trial participant returns to work, leisure, and activities around the home after an injury or surgery (measured as time to return to unrestricted activities).

We will measure knee function using the Oxford Knee Score (OKS), which is a validated and well-used 12 item questionnaire used to measure knee function when performing daily activities after total knee replacement surgery. The OKS is scored on a 0-48 scale with higher scores representing a better outcome.

We will use the Forgotten Joint Score (FJS-Knee) to measure how natural the replaced knee feels. The FJS-Knee is a 12 item questionnaire that aims to assess both function and feeling by asking about patients' awareness of their artificial knee while doing various daily activities. The FJS is scored on a 0-100 scale with higher scores representing a better outcome.

Overground walking kinematic gait analysis will be performed in the clinic environment using a ten-camera optoelectronic motion capture system. Primary gait outcomes will include the knee joint flexion and adduction angle magnitudes and range during the stance phase of gait. Secondary gait outcomes will include stride characteristics as defined above, knee transverse rotation during stance, knee flexion during swing, hip and ankle range of motion and peak magnitudes during stance.

We will use the Euro-Qol 5 Dimensions (EQ-5D) questionnaire, a widely used and well-validated quality of life tool, to measure participant quality of life. The EQ-5D is a comprehensive, 5-item compact health status classification and health state preference questionnaire.

We will use a modified version of the WHO's definition of PPSP, to include a minimum threshold of pain severity: Pain that began after surgery or a tissue trauma; Pain is in an area of preceding surgery or tissue trauma; Pain has persisted for at least three months after surgery; and The pain is not better explained by an infection, malignancy, a pre-existing pain condition or any other alternative cause. ≥4 out of 10 on the numeric rating scale (NRS) from the Brief Pain Inventory (BPI-SF) for "average pain over the last week". The scale ranges from 0 (no pain) to 10 (pain as bad as you can imagine)

We will use The Patient Global Impression of Change (PGIC) scale to assess patients' beliefs about the efficacy of treatment. The PGIC is one item and asks patients to rate the effectiveness of the treatment of interest on a 7-point ordinal scale ranging from "very much improved" to "very much worse

We will collect healthcare resource utilization information (e.g. hospitalization, physician visits) and information on productivity (e.g. time missed from work) to assist with health economic analyses.

We will collect all serious adverse events and surgery-related non-serious adverse events throughout the trial for safety monitoring purposes

We will report the number of revision surgeries within the study period including cases of periprosthetic joint infection, aseptic loosening, instability, poly wear, intractable pain, periprosthetic fracture etc.

Inclusion criteria Adult (18+) Unicompartmental knee OA with or without concomitant patellofemoral OA, requiring surgical treatment Two study surgeons independently agree that the patient is eligible for either treatment group Exclusion criteria Inability to provide informed consent (e.g. cognitive disability, language barrier) Revision knee surgery Simultaneous bilateral knee surgery Previous major knee surgery or trauma The robot or required components are unavailable (e.g. technical difficulties, robot-specific disposables out of stock) A CT scan cannot be obtained prior to surgery Patient does not wish to participate

We will share data upon reasonable request for non-commercial purposes. This may require an institutional data-sharing agreement.