Predictors of early aseptic loosening of endoprosthesis components during primary knee replacement

Relevance. Aseptic loosening of knee arthroplasty (ARKE) components is one of the common reasons for performing revision surgery. The permissible range of angular values of the postoperative alignment of the axis of the lower limb and the frontal location of the endoprosthesis components is a controversial issue. The purpose of the study: to determine the predictors of early aseptic loosening of endoprosthesis components during primary knee replacement. Material and methods. A comparative analysis of the studied (n = 31) and control (n = 55) groups was carried out. The study group included patients diagnosed with aseptic loosening of components, and the control group included patients who had not shown signs of loosening for at least 8 years. The initial data (gender, age, body mass index (BMI), side of the operation), as well as pre- and postoperative angular assessment of the axis of the lower extremities (aFTA, HKA) and reference angles (a/mLDFA, a/mMPTA) of the installation of endoprosthesis components were compared. Results. Age over 60.5 years and a BMI greater than 27.5 in patients increase the risk of loosening components by 2.9 and 2.6 times, respectively. Preoperative varicose deformity exceeding 9.5° in HKA and 6.5° in aFTA increases the risk of loosening of components by 9.6 and 23.14 times, respectively. Postoperative residual deformation exceeding 0.5° aFTA in any direction increases the risk of loosening of components by 8.7 times. The location of the tibial component in the hallux valgus position increases the risk of loosening of the components 2.8 times. Conclusion. In elderly patients who are overweight and have above-average varus deformity of the lower limb, preoperative planning should be carefully carried out, observing all protocol recommendations. And if a residual deformity is detected in the postoperative period and the tibial component is installed in the hallux valgus position, take such patients for enhanced monitoring and perform control X-rays every 6 months. If the progression of X-ray transparent lines is detected, immediately take the patient for a repeat operation, thereby increasing the chances of performing a conservative revision.