Preoperative Radiographic Evaluation of Medial Tibiofemoral Knee Osteoarthritis: Reproducibility, Reliability and Correlation With Ligament Injury

In advanced stage osteoarthritis or osteonecrosis of the articular bearing surfaces of the knee, the surgical therapeutic solutions consist of a replacement of the articular surfaces by prosthetic implants. Depending on whether these implants replace all or part of the articular surfaces they are called "total" or "uni compartmental" knee prosthesis.

The uni-compartmental medial prosthesis replaces only the medial tibiofemoral compartment of the knee and is therefore intended for patients with cartilaginous wear isolated from this compartment.

The uni-compartmental medial prosthesis has advantages over the total knee arthroplasty of being more economical in articular tissues of the knee, having better functional results and lower complication rates. Although this is debated, the survival rate of uni-compartmental prostheses in the international registers is lower than that of total knee prostheses.

One of the most common early failure factors of uni-compartmental prostheses is the absence of a functional anterior cruciate ligament. Other factors have also been identified and are sometimes highly debated such as the Kozinn and Scott criteria. The group of designers of the unicompartmental Oxford Uni compartmental prosthesis Knee Arthroplasty (OUKA) (Zimmer Biomet, Warsaw) proposed and validated expanded criteria. These criteria, exclusively radiographic, are grouped in a document called "decision aid" to check the functional status of the collateral ligaments medial and anterior cross, other compartments of the knee (lateral femoro-tibial and femoro-patellar).

In decision aid, the functional status of the anterior cruciate ligament is judged on the knee radiograph by the location of the osteoarthritic cup. If it is present and functional, the cartilaginous wear is anterior with a respect of the posterior portion of the tibial plateau.