Safety and Performance of the Journey™ II UNI Unicompartmental Knee System

Inclusion Criteria: * Subjects must meet all of the following criteria for inclusion in the study. 1. Unicompartmental, NIDJD, including OA, traumatic arthritis, or avascular necrosis. 2. Eighteen (18) years of age or older at the time of surgery. 3. Skeletally mature in the judgement of the PI. 4. Has met an acceptable preoperative medical clearance and is free of (or acceptably managed) cardiac, pulmonary, hematological, infection, or other conditions that would pose an excessive operative risk. 5. Willing and able to participate in required follow-up visits at the investigational site and to complete study procedures and questionnaires. 6. Consented to participate in the study by signing the EC-approved ICF. Exclusion Criteria: * Subjects meeting any of the following criteria must be excluded from participation in the study. 1. Correction of functional deformity. 2. Revision procedures where other treatments or devices have failed. 3. Treatment of fractures that are unmanageable using other techniques. 4. Inadequate bone stock to support the device which would make the procedure unjustifiable, including but not limited to severe osteopenia/osteoporosis or family history of severe osteoporosis/osteopenia. 5. Body Mass Index (BMI) \> 40. 6. Collateral ligament insufficiency. 7. Active infection, treated or untreated, systemic or at the site of the planned surgery or previous intra-articular infections. 8. Incomplete or deficient soft tissue surrounding the knee. 9. Conditions that may interfere with the UKA survival or outcome, including but not limited to Paget's disease, Charcot disease, vascular insufficiency, muscular atrophy, uncontrolled diabetes, renal insufficiency or neuromuscular disease. 10. Diagnosis of an immunosuppressive disorder. 11. Known allergy to study device or one or more of its components. 12. Pregnant or planning to become pregnant during the course of the study. 13. Subject, in the opinion of the PI, has an emotional or neurological condition that would pre-empt their ability or willingness to participate in the study including mental illness, mental retardation