This prospective study wants to demonstrate the safety and clinical performance of the 5C® MEDic Knee System following total knee arthroplasty. Additionally, all observed product-related complications are documented during the course of the follow-up study. These observations help to re-assess current (known) risks and identify new ones. The data obtained during this study is part of the post market surveillance.

Despite significant advancements in total knee replacement surgery, patient-reported satisfaction rates remain around 80-90%. The native knee joint kinematics are driven by the asymmetric articular surfaces where the medial tibial plateau is concave while the lateral is convex. The C-shaped medial meniscus has anterior and posterior lips that resist translation while the lateral meniscus has a circular shape allowing for 15° of anterior to posterior motion and an 11 mm of translation. As the knee flexes, the medial femoral condyle has a static centre of rotation without anteroposterior translation while the lateral femoral condyle translates posteriorly resulting in relative internal rotation of the tibia around a medial pivot.

The design of medial pivot knee prosthesis closely replicates these native knee kinematics. The medial ball in-socket design offers a highly conforming implant resulting in low contact stress and minimal edge loading.

On the other hand, the lateral arcuate trough provides less conformity therefore facilitating posterior translation of the lateral contact point during flexion recreating the native posterior femoral rollback. Over recent years, the medial pivot knee arthroplasty has gained popularity with multiple studies reporting enhanced patients' reported outcomes compared to other designs. Despite the favourable outcomes reported in the literature, there is still lack of sufficient data in the literature regarding the reported patient's outcomes and the overall revision rate of these medial pivot designs.

This prospective study wants to demonstrate the safety and clinical performance of the 5C® MEDic Knee System following total knee arthroplasty. Additionally, all observed product-related complications are documented during the course of the follow-up study. These observations help to re-assess current (known) risks and identify new ones. The data obtained during this study is part of the post market surveillance.

Inclusion Criteria:

1. Voluntary written informed consent of the participant has been obtained prior to any screening procedures

2. At least 18 years of age at the time of signing the Informed Consent Form (ICF)

3. The patient will be operated at the Leuven University Hospital (primary or revision surgery).

4. The patient will receive the 5C® MEDic Knee System (manufactured by implantcast GmbH).

5. The implantation will be performed according to the medical indications listed in the product specific Instruction for Use (IFU):

   1. Non-inflammatory degenerative joint disease including osteoarthritis and avascular necrosis,
   2. Post-traumatic osteoarthritis
   3. Treatment of fractures that are unmanageable using other surgical techniques
   4. Rheumatoid arthritis
   5. Revision arthroplasty (revision prosthesis)

6. The patient is willing and able to follow all study specific procedures and to attend the follow-up visits at the study site

7. The patient agrees to be contacted by telephone or by mail.

Exclusion Criteria:

1. The patient is <18 years of age, or unable to understand and sign a written informed consent form or legally incompetent or limited in his legal capacity.
2. Patient has history of malignancy within the past 5 years before screening.
3. Patients with Adipositas permagna (BMI ≥40 kg/m²).
4. Has a current infection as well as infections close (in the opinion of the investigator) to the knee joint within the last 3 years.
5. Known allergy to any of the implant materials.
6. Female who is pregnant or intends to become pregnant during screening and at the moment of operation
7. Not a suitable candidate for enrollment or unlikely to comply with the requirements of this study, as assessed by the Investigator.
8. Current alcohol and/or drug abuse or other addictions that might impair the patient's capacity to estimate the nature and the scope of the study.
9. Bilateral Total Knee Arthroplasty in a period of < 3 months.
10. Physiological or anatomical conditions, which preclude or are not expected to maintain adequate bony support of the implant or do not allow the implantation of a sufficiently large prosthesis, in the opinion of the investigator.
11. Bone tumors in the implant fixation area.
12. Has an untreated vascular diseases which limit blood supply to the affected limb, in the opinion of the investigator
13. Has a metabolic disorders that may impair bone formation.
14. In case of insufficient quantity and quality of bone stock, an alternative prosthetic treatment allowing for sufficient bony fixation should be considered.
15. Has severe axis deviation in treated knee under study and/or non-treated knee.
16. Ligament instability in treated knee under study.
17. Participation in an interventional trial with an investigational medicinal product (IMP) or device within the last four weeks before Screening.
18. Any other clinical history finding that, in the judgment of the investigator, would pose a potential hazard for performing a knee surgery

Individual Participant Data (IPD) will not be shared with third parties to ensure de-identification and maintain strict patient confidentiality in accordance with the General Data Protection Regulation (GDPR). Due to the highly specific nature of complex primary and revision hip arthroplasty-sometimes involving rare congenital pathologies and unique skeletal deformities-sharing raw, granular data poses a significant risk of 'deductive re-identification.' Even without direct identifiers, the combination of rare clinical characteristics and surgical dates could potentially allow for the identification of individual patients. Therefore, only aggregated, pseudonymized data and statistical summaries will be provided for analysis and reporting.