A clinical trial investigating the safety and effectiveness of Smith and Nephew's FDA-approved Porous Total Knee System, which is used to replace worn away and diseased knee joints. The aim of this study is to show that most patients who receive the Porous Total Knee System have reduced pain, greater mobility and a long-lasting implant post-surgery.

Patients who need a total knee replacement or have recently had a total knee replacement with the Smith and Nephew Porous Total Knee System will be enrolled into the study. Before surgery X-rays will be collected and questionnaires will be administered which ask the patient about knee pain, activities of daily living, quality of life and how they feel about their knee. The same X-rays and questionnaires will be asked before surgery and then after surgery at various intervals up to 10 years post-surgery.

Inclusion Criteria:

1. A) Subject needing primary TKA due to degenerative joint disease (primary diagnosis of osteoarthritis), post-traumatic arthritis or inflammatory arthritis.

   OR

   B) Subject has undergone primary TKA with Smith+Nephew Porous knee system in past 12 months to repair degenerative joint disease, post- traumatic arthritis or inflammatory arthritis and all the following conditions have been met:

   • Preoperative KOOS JR and radiographs have been obtained
   • 6-Month KOOS JR and radiographs have been obtained or these can be collected prospectively in window per schedule of events

2. Subject agrees to consent and to follow the prospective study visit schedule (as defined in the study protocol and informed consent form) by signing the Independent Review Board (IRB)/Independent Ethics Committee (IEC) approved informed consent form.

3. Subject is willing to attend study follow-up visits for up to five (5) years post-surgery.

4. Subject is able to read, understand, and communicate responses to Patient Reported Outcome assessments.

5. Subject is 18-80 years old (inclusive).

Exclusion Criteria:

1. Subject received TKA on the contralateral knee as a revision for a previously failed total or unicondylar knee arthroplasty.
2. Subject has a Body Mass Index (BMI) ≥ 40 at time of surgery.
3. Subject has ipsilateral hip arthritis resulting in flexion contracture.
4. At the time of enrolment, subject has one or more of the following arthroplasties that are not fully healed and well-functioning, as determined by the investigator: Ipsilateral or contralateral primary total hip arthroplasty or hip resurfacing arthroplasty; Contralateral primary total knee or unicondylar knee arthroplasty.
5. Subject has a condition that may interfere with the TKA survival or outcome (e.g. Paget's or Charcot's disease, vascular insufficiency, lupus, muscular atrophy, uncontrolled diabetes, moderate to severe renal insufficiency or neuromuscular disease).
6. Subject has a known allergy to one or more of its components of the study device.
7. Any subject with hardware present in distal femur or proximal tibia.
8. Any subject that meets the definition of a Vulnerable Subject per ISO 14155 Section 3.55.
9. Subject is entered in another drug, biologic, or device study or has been treated with an investigational product in the past 30 days.
10. Subject, in the opinion of the Investigator, has an emotional or neurological condition that would pre-empt their ability or willingness to participate in the study including mental illness, drug or alcohol abuse.
11. Subject is known to be at risk for lost to follow-up, or failure to return for scheduled visits.
12. Women who are pregnant, nursing, or of child-bearing potential who are not utilizing highly effective birth control measures.
13. Subjects who have participated previously in this clinical trial and who have been withdrawn.

Patient population will be selected by investigators from their clinics. Patients who report pain/mobility issues and who have been recommended for total knee replacement with Porous Total Knee System by their surgeon.