Polyethylene Wear Study on the Triathlon Total Knee Prosthesis

Comparison of conventional UHMWPE (ultra-high-molecular-weight polyethylene) with highly cross-linked polyethylene (X3) in a condylar stabilizing (CS) fixed bearing total knee prosthesis by means of RSA and clinical evaluation.

The goal of this study is to compare conventional UHMWPE with X3 highly cross-linked polyethylene in a CS fixed bearing total knee prosthesis (Triathlon Knee System: Stryker, Warsaw, USA) by means of RSA and clinical evaluation.

Eligibility Criteria:
Inclusion Criteria:

1. Patient is able to understand the meaning of the study and is willing to sign the Ethic Commission approved, study specific Informed Patient Consent Form.
2. Patients with a pre-operative knee score of \< 70.
3. Patients scheduled to undergo primary total knee replacement with any of the following indication.

   * Painful and disabled knee joint resulting from osteoarthritis.
   * One or more compartments are involved.
4. Need to obtain pain relief and improve function.
5. Ability and willingness to follow instructions, including control of weight and activity level, and to return for follow-up evaluations.
6. A good nutritional state of the patient.
7. Full skeletal maturity of the patient, patients who are at least 18 years of age.
8. Patients of either sex.

Exclusion Criteria:

1. The subject is morbidly obese, defined as Body Mass Index (BMI) of \> 40.
2. Skeletal immaturity of the patient, patients who are less than 18 years of age.
3. Patient has a flexion contracture of 15° and more.
4. Patient has a varus/valgus contracture of 15° and more.
5. Patients with a pre-operative knee score of \>70.
6. The subject has a history of total or unicompartmental reconstruction of the affected joint.
7. The subject will be operated bilaterally.
8. Patients who had a Total Hip Arthroplasty (THA) on contralateral and/or ipsilateral side within the last year that is considered to have an unsatisfactory outcome (Patients with contralateral and/or ipsilateral THA \> 1 year ago with good outcome can be included in the study).
9. Patients who had a Total Knee Arthroplasty (TKA) on contralateral side within the last 6 months that is considered to have an unsatisfactory outcome. (Patients with contralateral TKA \> 6 months ago with good outcome can be included in the study).
10. The subject has an active or suspected latent infection in or about the knee joint.
11. Osteomyelitis.
12. Sepsis.
13. Patients who will need lower limb joint replacement for another joint within one year.
14. The subject has a neuromuscular or neurosensory deficiency, which would limit the ability to assess the performance of the device.
15. The subject has a systemic or metabolic disorder leading to progressive bone deterioration.
16. The subject is immunologically suppressed or receiving steroids in excess of normal physiological requirements.
17. The subject's bone stock in compromised by disease or infection which cannot provide adequate support and/or fixation to the prosthesis.
18. The subject has had a knee fusion to the affected joint.
19. Female patients planning a pregnancy during the course of the study.
20. The patient is unable or unwilling to sign the Informed Consent specific to this study.