Polyethylene Wear Study on the Triathlon Total Knee Prosthesis

Study Overview
=================
Brief Summary
-----------------
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.

Detailed Description
-----------------
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.

Official Title
-----------------
Polyethylene Wear Study on the Triathlon Total Knee Prosthesis A Prospective Randomized Single Centre Roentgen Stereophotogrammetric Analysis (RSA) Study

Conditions
-----------------
Arthroplasty, Replacement, Knee

Intervention / Treatment
-----------------
* Device: Triathlon CS fixed bearing total knee prosthesis


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: 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. Patients with a pre-operative knee score of < 70. 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. Need to obtain pain relief and improve function. Ability and willingness to follow instructions, including control of weight and activity level, and to return for follow-up evaluations. A good nutritional state of the patient. Full skeletal maturity of the patient, patients who are at least 18 years of age. Patients of either sex. Exclusion Criteria: The subject is morbidly obese, defined as Body Mass Index (BMI) of > 40. Skeletal immaturity of the patient, patients who are less than 18 years of age. Patient has a flexion contracture of 15° and more. Patient has a varus/valgus contracture of 15° and more. Patients with a pre-operative knee score of >70. The subject has a history of total or unicompartmental reconstruction of the affected joint. The subject will be operated bilaterally. 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). 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). The subject has an active or suspected latent infection in or about the knee joint. Osteomyelitis. Sepsis. Patients who will need lower limb joint replacement for another joint within one year. The subject has a neuromuscular or neurosensory deficiency, which would limit the ability to assess the performance of the device. The subject has a systemic or metabolic disorder leading to progressive bone deterioration. The subject is immunologically suppressed or receiving steroids in excess of normal physiological requirements. The subject's bone stock in compromised by disease or infection which cannot provide adequate support and/or fixation to the prosthesis. The subject has had a knee fusion to the affected joint. Female patients planning a pregnancy during the course of the study. The patient is unable or unwilling to sign the Informed Consent specific to this study.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Conventional polyethylene inlay nitrogen/vacuum-packed (N2Vac)<br>Conventional UHMWPE inlay in a Triathlon Condyle Stabilizing (CS) fixed bearing total knee prosthesis | Device: Triathlon CS fixed bearing total knee prosthesis<br>* The patient will receive either the N2Vac polyethylene inlay or the X3 polyethylene inlay for their CS total knee.<br>|
| Active Comparator: Highly cross-linked polyethylene (X3)<br>X3 highly cross-linked polyethylene inlay in a Triathlon CS fixed bearing total knee prosthesis | Device: Triathlon CS fixed bearing total knee prosthesis<br>* The patient will receive either the N2Vac polyethylene inlay or the X3 polyethylene inlay for their CS total knee.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assessment of Polyethylene Inlay Wear by Roentgen Stereophotogrammetric Analysis (RSA). | RSA is a highly accurate technique for the assessment of three-dimensional migration and micro motion of a joint replacement prosthesis relative to the bone it is attached to. Because of the high accuracy, RSA can also be used to measure wear in knee replacements and is used in this study for the assessment of the wear of the two polyethylene inlay types N2Vac polyethylene and X3 polyethylene. | 1, 2 and 5 years follow-up | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assessment of Prosthetic Migration Results After Two Years by RSA. | RSA is a highly accurate technique for the assessment of three-dimensional migration and micro motion of a joint replacement prosthesis relative to the bone it is attached to. This study evaluates the prosthetic migration results with focus of the two years results of the Triathlon CS Peri-Apatite coated tibial and femoral components. | 3 and 6 months,1, 2 and 5 years follow-up | 
| Investigation of Clinical Performance and Patient Outcome With the Knee Society Score (KSS) | The Knee Society Clinical Rating System is comprised of two distinct sub-scores: one for pain, range of motion (ROM) and joint stability, and one for functional parameters. Sub-scores range from a potential minimum score of 0 to a maximum score of 100 points. Although the specific scores are not distinguished as excellent, good, fair, or poor, a higher value represents a better outcome. | Pre-operative, 6 weeks, 3 and 6 months, 1, 2 and 5 years | 
| Investigation of Clinical Performance and Patient Outcome With the Short Form Patient Questionnaire (SF-36) | The SF-36 Health Survey is a 36-item patient completed questionnaire to measure general health and well-being. It includes a physical and mental status component score; each ranging from 0-100. Low values represent a poor health state and high values represent a good health state. | Pre-operative, 6 weeks, 3 and 6 months, 1, 2 and 5 years | 
| Investigation of Clinical Performance and Patient Outcome With the EuroQuol - 5 Dimension (EQ-5D) Patient Questionnaire | The EuroQol-5 Dimension (EQ-5D) is a subject-completed questionnaire designed to assess subject health state values. The EQ-5D consists of 2 areas; EQ-5D descriptive system and the visual analogue scale (VAS). The EQ-5D descriptive system comprises the following five dimensions: mobility self care, usual activities, pain/comfort and anxiety/depression. Each dimension has 3 levels indicating no problems, some problems or extreme problems. The index values on a scale between -1 (low) and 1 (high) are showing the average health status according to the 5 dimensions: A low score shows worse health and a high score shows better health. With the EQ VAS the respondents can report their perceived health status with a grade ranging from 0 (the worst possible health status) to 100 (the best possible health status). | Pre-operative, 6 weeks, 3 and 6 months, 1, 2 and 5 years | 
| Investigation of Clinical Performance and Patient Outcome With the Lower Extremity Activity Scale (LEAS) Patient Questionnaire | The LEAS is completed by the participant to assess activity level. Activity levels were ordered in terms of intensity from 1 to 18, with 18 indicating the highest activity level. | Pre-operative, 6 weeks, 3 and 6 months, 1, 2 and 5 years |