RESULTS OF MATHEMATICAL MODELING OF TENSION-DEFORMED CONDITION OF COMPONENTS OF KNEE JOINT ENDOPROSTHESIS IN CONDITIONS OF PRESENCE OF DEFECT EFFECTS

Abstract

Summary. Gonarthrosis is reported in 50.6–54.5% of cases among patients with the lower extremities large joints’ dystrophic diseases. In 86% of cases, it affects people of working age, and in 6.5–14.6% - leads to disability. That is why, gonarthrosis is an acute medical and social problem. However, despite the large number of surgeries, the matter of choosing a method (bone plastic, metal insertion) to cover a bone bed’s defects for total knee arthroplasty (KJ) is still ambiguous. Objective: to conduct a computer simulation of strains occurring upon a regular and extended tibial stem of a knee prosthesis, depending on different tibial condylar defects. Materials and methods: the laboratory of biomechanics of the SI “ITO NAMS of Ukraine” created a computer model to study stress-deformed conditions of a KJ endoprosthesis upon a varus deformity of an extremity and knee arthroplasty with a regular and an extended tibial stem, if a bone defect has been replaced with a bone autograft of 5 and 10 mm. Results. It was determined that if a knee arthroplasty occurs upon conditions of a varus deformity, with an internal tibial condyle’s defect, the defect can be filled with an autograft insert up to 5 mm high, and a regular (short) prosthetic stem is suitable. If such a lesion is from 5 mm to 13.5 mm, an extended prosthetic stem is biomechanically justified. If a height of the defect exceeds 13.5 mm, it must be replaced with a massive metal insert. Practical essence: the study will be helpful to elaborate a differentiated approach to various tibial condyles’ defects treatment in the course of the total knee arthroplasty. Conclusions. The implementation of recommendations resulting from this study will increase the efficiency of treatment to this severe category of patients.