The purpose of this study is to demonstrate superior accuracy with the Navio ™ Robotic-assisted Surgical System in achieving desired post-operative mechanical alignment, compared to TKA procedures using standard instruments. An additional study purpose is to document clinical and patient-reported outcomes in subjects receiving TKA with the Navio ™ system.

Total Knee Arthroplasty (TKA) has become an effective and reliable treatment for arthritis of the knee (1). TKA is associated with low morbidity and mortality, and its effectiveness in reducing joint pain and improving range of motion is well established. In 2014, over 750,000 knee replacements were performed in the US (2).

A significant innovation in TKA has been the introduction of computer navigation and robotic-assisted surgery (3). One such technology is the Navio™ Robotic-assisted Surgical System. This system is a semi-autonomous image-free system. During the surgery, the surgeon maps the condylar landmarks and determines alignment indices to define the volume and orientation of bone to be removed. The tools to remove the bone and place the implants are controlled and manipulated by the surgeon with the guidance of a 3-dimensional digital map of the surgical surface.

Originally the Navio™ system was launched for use in unicondylar knee replacement only. To date, there have been over 1000 unicondylar knee replacement surgeries using the system. In 2017, Smith & Nephew Inc. expanded the indications for the Navio™ system to include TKA. The purpose of this multicenter, prospective study is to evaluate outcomes associated with this new indication.

Inclusion Criteria:

1. Subject requires primary total knee arthroplasty with the Journey II BCS or Cruciate-Retraining (CR) Systems due to degenerative joint disease (primary diagnosis of osteoarthritis, post-traumatic arthritis, avascular necrosis, rheumatoid arthritis.
2. Subject was considered skeletally mature at the time of cone implantation (at least 18 years or older.)
3. Subject agrees to consent to and to follow the study visit schedule (as defined in the study protocol and informed consent form) by signing the IRB/EC approved informed consent form.
4. Subject plans to be available through two (2) years postoperative follow-up.

Exclusion Criteria:

1. Subject has BMI ≥ 40.
2. Subject has condition(s) that may interfere with the TKA survival or outcome (i.e., Paget's or Charcot's disease, vascular insufficiency, muscular atrophy, uncontrolled diabetes, moderate to severe renal insufficiency or neuromuscular disease, or an active, local infection).
3. Subject is deemed by investigator to require a constrained or deep dish tibial insert.
4. Subject has inadequate bone stock to support the device (severe osteopenia, history of severe osteoporosis or severe osteopenia).
5. Subject has mental or neurologic condition(s) that may pre-empt the ability or willingness to restrict activities.
6. Subject is 80 years of age or older.
7. Subject is a prisoner or impending incarceration.

To eliminate the potential for selection bias, Investigators should screen all subjects undergoing a Navio™ assisted TKA. In order to do so, only the existing information obtained per standard routine medical procedures will be used. No study-specific screening procedures, activities or questionnaires will be performed during pre-screening.

Time of surgery (i.e., device implantation) through end of the study (2 year post-operative follow-up).

The Intent-to-Treat (ITT) population used for safety analyses and included all consented participants enrolled in the study that received Total Knee Replacement with NAVIO ™ Robotic-assisted Surgical System.