A Prospective Randomized Control Study on CR vs MC Polyethylene Bearing With Persona Total Knee System in Total Knee Arthroplasty

Background Knee replacement is an established treatment for late stage osteoarthritis (OA) of the knee (Charnley et al. 1961). There are different approaches to prosthetic replacement and current practices and designs are often based on limited evidence (Plate et al. 2012). There have been individual cohort studies, indirect comparisons and retrospective studies to test the efficacy of a variety of different total knee replacement devices but there are very few high quality investigations of new paradigms or significant design change. Those studies that do exist have usually been undertaken to address a combination of design changes and many involve only short-term assessments (Mäkelä et al. 2008). Ongoing research and development programs for knee replacement are increasingly taking account of the needs of the changing characteristics of the late stage OA knee population.

There is an increasing demand for joint replacement in a younger population (Mäkelä et al. 2014). Due to the changing demographics of joint replacement, the population of younger patients are seeking options that not only correct their disease or deformity, but do not limit them in activity (Geerdink et al. 2009). Activities of daily living take higher priority in this patient group, and patients needing total joint replacement do not have many options that accommodate higher levels of activity.

Studies have shown that modern implant designs can potentially improve outcome. Therefore new implants are introduced to the marked with the theoretical benefit of improved implant survival and superior patient reported outcomes. Within Total knee arthroplasty, design changes are introduced in attempt to improve knee kinematics, improve alignment and functionality, but those potential improvements need to be evaluated Recently, Zimmer-Biomet have introduced Persona Total Knee system with design changes that include asymmetric tibia plate, increased medial pivoting and more extensive choices in respect to poly thickness, all with the purpose to improve balancing, stability and longevity. One design change that is introduced is the medial congruent (MC) polyethylene to be used instead of standard cruciate retaining (CR) design. The theoretic proposed benefit of MC polyethylene bearing is improved kinematics mimicking native knee motion. However, currently no studies exist evaluating outcome following use of MC polyethylene bearing. Therefore such design changes and proposed benefits need to be evaluated in a prospective clinical trail, with focus on patient safety, satisfaction and implant durability.

The purpose of the proposed Randomized Clinical Trial (RCT) is to evaluate the outcome and safety of a newly designed polyethylene bearing by comparing it with a control group of patients implanted with an established polyethylene bearing.

Device description