Comparison of the strength characteristics of a carbon friction pair of a hip joint endoprosthesis, including components from monolithic or non-monolithic pyrolytic carbon

Introduction The problem a large number of revision operations due to aseptic loosening after primary hip arthroplasty necessitates the search for a new material for a friction pair. The pyrocarbon, which has high tribological characteristics, can be used both in a monolithic and in a prefabricated design; however, the manufacture of a monolithic pyrocarbon block complicates production.Aim Compare the strength characteristics of the stem head and liner designs with monolithic and non-monolithic pyrocarbon.Materials and methods To assess the reliability of the designs, a digital mathematical model of the head and liner implants with a monolithic and non-monolithic pyrocarbon component was built. After the manufacture of prototypes friction pairs, an assessment of the static load on bench tests was carried out.Results While analyzing the mathematical model, the construct of non-monolithic pyrocarbon broke in one of the experiments, while the strength of the construct of monolithic pyrocarbon was 4.5 times higher than the stresses arising under load. While studying the maximum static load, the friction pair from monolithic pyrocarbon exceeded the maximum possible load in the human hip joint by 5 times.Discussion The studies allow us to be confident about the reliability of the design in in vitro studies, which will create conditions for reducing the number of revision surgeries after hip arthroplasty.Conclusion Based on the data obtained, the design of the head and liner of the hip joint endoprosthesis with a friction pair made of carbon material will provide high reliability under conditions of functioning in the hip joint at maximum loads. It serves as a prerequisite for conducting a clinical study of the proposed friction pair.