In-vivo Wear Behaviour of AS Coated Versus Uncoated Columbus® Total Knee Prosthesis

Implant survival

Kaplan-Meier Analysis is a standard statistical method to describe the survival of human subjects or medical products over a defined time period.

Time frame: until 10 years postoperatively

Quality of Life [EQ-5D-5L] compared to baseline

The 5-dimension 5-level measure of the health status, developed by the EuroQol Group (EQ-5D-5L) is a simple and generic measure for clinical and economic assessment. Instructions for the user are directly included into the questionnaire and it consists of two pages. One cover five different dimensions (mobility, self care, usual activities, pain/discomfort, anxiety/depression) and the other one the EQ visual Analogue Scale (EQ-VAS). The VAS scale records the self rated health status of the patient from the level "the worst health you can imagine" to "the best health you can imagine". The answer of each of the five dimensions result in a 1-digit number that expresses the level selected for that dimension. The digits for the five dimensions can be combined into a 5-digit number that describes the patient's health state.

Time frame: preoperatively and 3 months, 12 months, 2 years, 5 years, 10 years postoperatively

Progress of Clinical Outcome (Forgotten Joint Score-12) over follow-up period

The Forgotten Joint Score-12 (FJS-12) Knee was designed to assess patient outcome in patients undergoing conservative or operative treatment of the knee. These Patient Reported Outcome (PRO) questionnaires focus on patients' awareness of a specific joint in everyday life. In 12 Items the awareness for the artificial joint is assessed by the patient, each on a five point scale (Never / Almost Never / Seldom / Sometimes / Mostly) The Forgotten Joint Score assessment consists of 12 questions and is scored on a 0-100 scale. The higher the score, the less the patient is aware of their affected joint when performing daily activities

Time frame: 3 months, 12 months, 2 years, 5 years, 10 years postoperatively

Progress of Clinical Outcome [Oxford Knee Score] compared to baseline

The Oxford Knee Score (OKS) is a reliable 12-item, patient-reported questionnaire originally developed and validated specifically to assess function and pain in patients undergoing total knee replacement. It is short, reproducible, valid and sensitive to clinically important changes over time. Each of the 12 questions on the OKS is scored in the same way with the score decreasing as the reported symptoms increase (i.e. become worse). All questions are laid out with response categories denoting least (or no) symptoms to the left of the page (scoring 4) and those representing greatest severity lying on the right hand side (scoring 0), as detailed for question 1 below. This method, when summed, produces overall scores running from 0 to 48 with 48 being the best outcome,

Time frame: preoperatively and 3 months, 12 months, 2 years, 5 years, 10 years postoperatively

Radiographic comparison of alignment over time

Radiographs shall be standardized between centres as far as possible. Unless limited by patient or equipment constraints, all follow-up imaging examinations will be obtained according to the radiographic protocol of the hospital and the set routine. The radiographic evaluation of Alignment combines Hip-Knee-Angle, femoral and tibial component alignment

Time frame: baseline (assessed at discharge from hospital up to 10 days postoperatively); 3 months; 12 months; 5 years; 10 years

Radiographic comparison of implant migration over time

Radiographs shall be standardized between centres as far as possible. Unless limited by patient or equipment constraints, all follow-up imaging examinations will be obtained according to the radiographic protocol of the hospital and the set routine. The radiographic evaluation of implant migration comprises tibial and femoral components in m/l and a/p direction,

Time frame: baseline (assessed at discharge from hospital up to 10 days postoperatively); 3 months; 12 months; 5 years; 10 years

Radiographic comparison of tibial slope over time

Radiographs shall be standardized between centres as far as possible. Unless limited by patient or equipment constraints, all follow-up imaging examinations will be obtained according to the radiographic protocol of the hospital and the set routine. Any changes of Tibial slope over the follow-up period is documented in the radiographic evaluation

Time frame: baseline (assessed at discharge from hospital up to 10 days postoperatively); 3 months; 12 months; 5 years; 10 years

Radiographic comparison of the joint line over time

Radiographs shall be standardized between centres as far as possible. Unless limited by patient or equipment constraints, all follow-up imaging examinations will be obtained according to the radiographic protocol of the hospital and the set routine. Any changes of the joint line over the follow-up period is documented in the radiographic evaluation

Time frame: baseline (assessed at discharge from hospital up to 10 days postoperatively); 3 months; 12 months; 5 years; 10 years

Adverse events / serious adverse events

During the course of the study, any upcoming intra- or postoperative (serious) adverse events (AE / SAE) or device effects related or not related to the product under investigation or the procedure, will be documented in the dedicated Case Report Forms. The total number of AEs will be summarized and further evaluated by the sponsor and reported according to local legislation and necessity. Recorded complications will be categorized and analyzed in order to assess the safety of the investigational product

Time frame: During the course of the study up to 10 years postoperatively

Number of Participants with radiological complications over time

Radiographs shall be standardized between centres as far as possible. Unless limited by patient or equipment constraints, all follow-up imaging examinations will be obtained according to the radiographic protocol of the hospital and the set routine. All radiologically evident complications (including fracture, wear, loosening or radiolucencies) are cumulatively documented over the period of follow-up.

Time frame: During the course of the study up to 10 years postoperatively

Biomechanical analysis of retrievals in case of revision

Available retrievals of explanted investigational products will be analysed by the biomechanical laboratory of the sponsor according to an analysis protocol which includes the oxidation profile, the wear behaviour, the mechanics and the cumulative linear abrasion of these retrievals.

Time frame: During the course of the study up to 10 years postoperatively