The purpose of this prospective randomized study is to evaluate iAssist with respect to radiographic, clinical and economic outcomes in comparison to conventional instrumentation in primary total knee arthroplasty using the Persona knee system among patients with BMI>=30.

Inclusion Criteria:

1. Male or female

2. Needs a primary TKR on the left or right knee

3. Diagnose of non-inflammatory degenerative joint disease (e.g., osteoarthritis, post-traumatic arthritis, avascular necrosis, etc.)

4. Over 18 years old

5. BMI>=30

6. Able to:

   • Understand what participation in the study entails and give written informed consent, and
   • Follow surgeon/staff instructions, and
   • Return for all follow-up evaluations, and
   • Able and willing to undergo a preoperative full-leg, standing radiographs (all cases)
   • Willing to consent (patient or his/her legal guardian) to participate in the study by signing and dating an approved consent.
   • Meet an acceptable preoperative medical clearance and is free of or treated for cardiac, pulmonary, hematological or other conditions that would pose excessive operative risk.

7. Presence of varus or valgus deformity of 15 degrees or less.

Exclusion Criteria:

1. Currently enrolled in an investigational new drug or device study
2. Active Infection (including septic knee, distant infection, or osteomyelitis)
3. Severe hip arthrosis
4. Neurological disorders (including, but not limited to Parkinson's disease)
5. Prior ipsilateral unicompartmental knee arthroplasty, TKA, knee fusion or patellectomy
6. Hip or knee ankylosis
7. Inflammatory joint disease.
8. Either rheumatoid or post-traumatic knee arthritis
9. Scheduled for simultaneous bilateral TKA
10. Indications of intra- and/or extra-articular deformations that would eliminate or tend to eliminate adequate implant support or prevent the use of an appropriately sized implant, such as polio, history of tibial plateau fracture, etc.
11. Any metal within 150 mm of the joint line for the operative-side knee
12. Knee deformities greater than 15 degrees of fixed varus, valgus, or flexion contracture on initial physical examination
13. A female who is pregnant or lactating
14. Current involvement in any personal injury litigation, medical-legal or worker's compensation claims
15. Arterial disease or stents that would exclude the use of a tourniquet
16. Insufficient quality or quantity of bone to support the implant due to prior knee surgery (or surgeries), cancer, metabolic bone disease, osteoporosis/osteopenia (diagnosed or treated with medication), active/old/remote infection, etc.
17. Mental condition that may interfere with his/her ability to give an informed consent or interfere with his/her ability or willingness to fulfill the requirements of the study.
18. Condition that would place excessive demands on the implant (e.g., Charcot's joints, muscle deficiencies, multiple joint disabilities, skeletal immaturity, etc.).
19. Collateral ligament insufficiency.
20. Immunosuppressive disorder (e.g., AIDS, etc.) that would require cytotoxic drugs, corticosteroids, large dose of irradiation, or antilymphocytic serum.
21. An existing condition that would, in the opinion of the investigator, compromise participation or follow-up in this study