The purpose of this study is to verify that an orthopedic surgical assist robot (ROSA Knee System) can provide intraoperative adjustment of osteotomy angle and volume for total knee arthroplasty (TKA) based on feedbacks obtained from intraoperative soft tissue conditions. A total 80 cases will be enrolled at one study site with a postoperative follow-up period of 2 years.

The objectives of the study are to document that ROSA Knee System can provide intraoperative planning adjustment based on feedbacks obtained by laxity as well as gaps to locally preferred surgeon's operative philosophy. This will also provide accuracy, intraoperative soft tissue release as well as patient outcome on locally preferred surgical technique.

The primary endpoint is defined as the mean absolute difference between X-Atlas image-based pre-op plan & intra-op final plan.

The secondary endpoints include Kinematic Analysis, EuroQol 5 dimensions (EQ-5D), Rehabilitation record, Knee Society Score (KSS) 2011, image assessment and Safety up to 2 years postoperatively.

Inclusion Criteria:

• 20 years and over
• Skeletally matured
• Decision to have Total Knee Arthroplasty with ROSA Knee System being made independently and prior to recruitment into study
• Willing and able to complete scheduled follow-up evaluations as described in the study protocol
• Has participated in the informed consent process and is willing and able to sign an Institutional Review Board (IRB)/Ethics Committee (EC) approved informed consent form

Exclusion Criteria:

• Has serious bone defect(s), which require(s) metallic augment, synthetic bone or allograft
• Is septic, has an active infection or has osteomyelitis at the affected joint
• Has vascular insufficiency, muscular atrophy at the implant site or neuromuscular disease which might jeopardize the outcome of the surgery
• Has any concomitant disease which is likely to jeopardize the functioning or success of the implant
• Is known to be pregnant
• Is a prisoner, known alcohol or drug abuser or mentally incompetent or unable to understand what participation in this study entails
• Has a known sensitivity or allergy to one or more of the implanted materials

The study population will comprise of males and females who require primary total knee arthroplasty and satisfy the inclusion/exclusion criteria outlined in this section of the protocol. In order to avoid potential selection bias, each Investigator will offer study participation to each consecutive eligible patient presenting as a candidate for primary total knee arthroplasty using the commercially available Zimmer Biomet total knee systems. Eligible candidates who express interest in study participation will be offered Informed Consent.