Surgical aspects of positioning individual three-flanged implants in replacement of bone defects in revision hip arthroplasty

A modern feature of revision arthroplasty is a decrease in the age of patients, as well as an increase in the number of patients who underwent repeated revision surgeries. Massive bone defects that occur in this group of patients represent the most difficult category for treatment.The purpose of the study: to determine the influence of various factors on the positioning accuracy of individual three-flange implants in revision hip arthroplasty.Materials and methods: A retrospective analysis of the data on the use of individual three-flange constructions in revision hip arthroplasty in 12 patients from March 2020 to February 2022 was carried out. Among them, there were 9 women and 3 men aged 43 to 79 years (mean age 64 years).Results: The mean deviation between the planned inclination and the final postoperative position was -0.96º (MKD -5.9 - 1.9º). The average deviation ofanteversion was 2.7º (MKD 0.4 - 5.4º). The average value of implant reversal was 1.8º (MKD -1.2 - 3.6º). Given the allowable 10° deviation, in 100% of cases, the installed three-flange structures had the correct position. When assessing the center of rotation, exceeding the established limits by more than 5 mm was observed only in 3 (25%) cases.Conclusion: The analysis of the results showed that with the approach we used, in most cases (75%), the planned parameters were achieved when positioning the three-flange structure. The main factors determining the accuracy of positioning include the initial quality of the obtained CT data and the performed 3D reconstruction, and the presence of artifacts. Taking into account the individuality and variety of designs of three-flange structures, it is fundamental to accurately recreate the center of rotation, and complementarity in the absolute sense is hardly achievable. The most important thing is to achieve reliable support and stable fixation in the area of the flanges.