This study compares and evaluates differences in movement analysis, patient-reported outcome and radiological assesment between patients undergoing total knee arthroplasty with use of either Zimmer Biomet NexGen and Zimmer Biomet PERSONA

Osteoarthritis causes the joints to become painful and stiff. Osteoarthritis of the knee is a common condition that is expected to be a lot more frequent in the next two decades. As a consequence, an increase of total knee replacement surgery is predicted. Total knee replacement surgery is offered when knee pain and stiffness caused by osteoarthritis can no longer be managed and these symptoms significantly impact on an individual's normal activities of daily living. Most total knee replacements are successful but up to 34% of all patients have poor functional outcomes following surgery. This leaves affected people at a greater risk of reduced physical activity and thus impacts longer-term general health. Poor outcomes are therefore of importance to patients and have a considerable financial and service-provision impact on National Health Service (NHS) care. While patient-related characteristics and their relationship to patient outcomes have been identified, few studies have been undertaken to determine how kinematic outcomes (how the prosthetic knee moves) are related to functional outcome and patient satisfaction. The kinematic outcome of a total knee replacement is hypothesised to relate to both the structural design (shape) of the implant and the surgical procedure itself. To date, no studies have investigated the kinematic outcomes of different total knee replacement prosthesis designs through a range of typical activities of everyday mobility (functional outcomes). Whilst it is known that long term success of total knee replacement depends largely upon correct alignment of the prosthesis components during surgery, no studies have looked at the anatomical alignments of the osteoarthritic knee prior to undergoing surgery (using Computerised Tomography (CT) scanning). The aim of the study is to examine relationships between movement analysis (kinematic and functional outcomes), patient reported outcome measures (PROMS) and CT measurement, both pre- and post-operatively, between two knee prosthesis including one that has been designed to improve functional outcomes.

Inclusion Criteria:

1. Listed for a primary total knee replacement (TKR) at the Orthopaedic and Rehabilitation Department Medical University of Warsaw
2. Indication for the TKR is primary osteoarthritis of the knee joint involving one or more compartments
3. Aged 18 or over
4. Patient willing to provide full informed consent to the trial

Exclusion Criteria:

1. Listed for a single-stage bilateral TKR procedure
2. Severe symptoms in the contralateral knee so as to require staged bilateral knee replacements within 6 months of the primary procedure
3. Fixed flexion deformity of 15 degrees or greater who will require excessive resection of the distal femur
4. Clinically assessed uncorrectable varus/valgus deformity of 15 degrees or greater
5. Any co-morbidity which, in the opinion of the investigator, is severe enough to present an unacceptable risk to the patient's safety
6. Inflammatory arthritis
7. Previous septic arthritis in the affected knee joint
8. Previous surgery to the collateral ligaments of the affected knee
9. A contralateral total knee replacement that has been implanted less than one year from the date of consultation
10. A contralateral total knee replacement that is severely painful
11. Patients on warfarin or novel oral anticoagulants (NOACs)
12. Will not be resident in the catchment area for at least 6 months post-surgery
13. Undertaking the surgery as a private patient
14. Patients who, in the opinion of the clinical staff, do not have capacity to consent
15. Patients who are pregnant
16. Unable to understand written and spoken Polish

Participant will not be informed which type of prosthesis was used in their particular case.

Outcomes Assessor will not be informed which type of prosthesis was used in particular patient.