The purpose of this study is to assist surgeons and patients in answering the question "Should I have both knees replaced at the same time, or should I just do one and wait to do the second one?"

This is a multi-center randomized controlled trial of 224 patients in order to clearly delineate differences in post-operative outcomes and the trajectory of recovery between simultaneous and staged bilateral KA. The primary outcome measure is difference in generic health related quality of life between the two groups measured 1 year following surgery. Secondary outcome measures include differences in joint specific scores, time off work, satisfaction and costs.

This trial will inform patients and clinicians about differences in recovery, function and efficacy of the procedure to aid in the selection of treatment pathway to best suit the patient.

Inclusion Criteria:

• Patients considering bilateral knee arthroplasty
• Patients must sign the consent form
• Patients must be willing to complete the study questionnaires for the duration of the study

Exclusion Criteria:

• Patients who require simultaneous bilateral knee replacement surgery in order to manage significant bilateral flexion or valgus knee contractures where staged procedures may result in suboptimal outcomes by increasing the risk of post-operative flexion contracture in the "first replaced" knee
• patients who are unable to complete the questionnaires