Comparison of Pivotal Medial Polyethylene Versus Ultra-congruent in Total Knee Arthroplasty

Total knee arthroplasty is usually effective at improving the quality of life of patients suffering from arthritis.

Over the years, patient expectations about the quality of life post-implantation continue to rise.

It is therefore essential to improve continuously surgical techniques and implants to fulfill patient expectations in terms of pain and movements.

The prosthetic device is composed of a metallic femoral unit, which imitates the articular surface of the femur, and a metallic tibial baseplate covered with a polyethylene (a highly resistant polymer) insert which articulates between the femur and the tibia. This insert can take several forms such as medial pivot or ultra-congruent.

This polymer provides an interface between the two metallic units forming the prothetic device. It has two roles: it provides a lasting contact surface and it offers stability to the knee in substitution of the ligaments.

In order to achieve this double function, a polyethylene system, called " medial pivot " was conceived.

This system mimics as close as possible the anatomical knee kinematics with a rotational movement that the " ball in socket " tries to reproduce by the mediatisation of the pivot point during knee flexion.

Currently, there are no randomized study which were conducted comparing these two types of polyethylene.

Total knee arthroplasty is usually effective at improving the quality of life of patients suffering from arthritis.

Over the years, patient expectations about the quality of life post-implantation continue to rise.

It is therefore essential to improve continuously surgical techniques and implants to fulfill patient expectations in terms of pain and movements.

The prosthetic device is composed of a metallic femoral unit, which imitates the articular surface of the femur, and a metallic tibial baseplate covered with a polyethylene (a highly resistant polymer) insert which articulates between the femur and the tibia. This insert can take several forms such as medial pivot or ultra-congruent.

This polymer provides an interface between the two metallic units forming the prothetic device. It has two roles: it provides a lasting contact surface and it offers stability to the knee in substitution of the ligaments.

In order to achieve this double function, a polyethylene system, called " medial pivot " was conceived.

This system mimics as close as possible the anatomical knee kinematics with a rotational movement that the " ball in socket " tries to reproduce by the mediatisation of the pivot point during knee flexion.

Currently, there are no randomized study which were conducted comparing these two types of polyethylene.

Inclusion criteria

• Subjects 18 to 90 years of age, eligible for a primary total knee replacement for gonarthrosis
• Competent subjects able to give informed consent to participate in the research
• Affiliation to the social security system

Exclusion criteria

• Infection history of the knee to be replaced
• Deformity greater than 15 degrees
• Any surgical and/or anesthetic contraindication, or any condition deemed by the investigator to be incompatible with the research.
• Any contraindication mentioned in the instructions for use of the medical device
• Pregnant or breastfeeding women
• Recent infection history of the surgical site
• Adults who are subject to a legal protection measure or who are unable to express their constent (Article L1121-8 of the French Public Health Code) and subjects under judicial protection (article L. 1122-2 FPHC)
• Subjects who refuse to participate