Optimizing the value of the posterior condylar offset, proximal tibial resection and slope in order to achieve the right balance of the posterior cruciate ligament - clinical application of the molding function of the two parts of the PCL

INTRODUCTION: In order to achieve the right balance of the posterior cruciate ligament using the skeletal method is very difficult, almost impossible (Mahoney). Our hypothesis for the right balance of the PCL by using the skeletal method is based on several defined facts: - PCL is a union based of two anatomically independent, but functionally synergic parts, posteromedial and anterolateral part. - The length of the posteromedial part of the PCL is determined by the belonging of the medial compartment and is shortest in varus and longest in valgus deformation. - The length of the anterolateral part of the PCL, placed centrally is unchangeable (cca 38 mm) in every knee and is independent from the anatomical appearance (deformation). - The cylindrical shape of the distal posterior part of the femur (Ficat) depends of the molding function of the PCL (Kapandji) and is a result of the proportion of the both parts of the PCL that is consisted of: shorter posteromedial part, less bone stock on the medial and more bone stock on the lateral condyle (varus knee) and vice versa, longer posteromedial part, more bone stock on the medial condyle and less on the lateral (valgus knee). According to that, the neutral bone stock is achieved by equalization of the lengths of the two parts (common radius of the cylinder) of the PCL, that is basis for the interligamentary balance of the posterior cruciate ligament. METHODS: The basic characteristics of the interligamentary balance of the PCL that we started in 2008 are the following: 1. Posterior condylar offset is equal to the even length of the both part of the PCL. 2. Decrease of the values of proximal tibial resection from 10 in varus to 4-6 in valgus. 3. Femoral valgus cut from 6 in excessive varus deformity to 4 in valgus. RESULTS: The clinical evaluation of the cases divided in groups excessive varus, mean varus, valgus type 1, 2 (Krakow) showed right distribution in the groups of the postoperative ROM and intraoperative tenacity of the PCL (POLO test and palpation test), as a confirmation to the hypothesis. CONCLUSIONS: The ligamentary apparatus of the knee by the molding function depends on the skeletal morphology of the distal posterior femur to the degree that there aren’t two identical knees (Kapandji). According to that, every PCL has its own knee.