Background. The problem of revision arthroplasty in modern orthopedics is extremely acute, as evidenced by an increase in its frequency. However, the probable factors that lead to the development of instability of the knee endoprosthesis components, according to various authors, differ among themselves, and the methods for evaluating the outcomes of arthroplasty require improvement as well. The purpose was to determine the risk factors that affected the outcomes of knee replacement, and to propose a methodology for assessing the latter. Materials and methods. The work is based on the analysis of treatment outcomes in 105 prosthetic patients. The operations were performed from 2010 to 2021 at the basis of the clinic for orthopаedics and traumatology of adults at the State Institution “Institute of Traumatology and Orthopаedics of the National Academy of Medical Sciences of Ukraine”. A clinical and anamnestic examination of patients was carried out with evaluation of the body mass index, concomitant pathology, and working conditions, the axis of the operated limb, early postoperative complications and factors leading to joint stiffness; radiographic (with the determination of periprosthetic bone tissue lysis zones) and sonographic examination was conducted. The data obtained are statistically processed. Results. The risk factors that influenced the instability of knee endoprosthesis components were as follows: heavy physical work (t = 1.34 and higher, p < 0.05); obesity with body mass index ≥ 30 (t = 2.24 and above, p < 0.05), residual deformity (хi2 = 4.55, n = 2, p < 0.05); early postoperative complications (Z = 7.25, p < 0.01), violation of cementing technique for the femoral (t = 1.63 and higher, p < 0.05) and tibial component (t = 1.36 and above, p < 0.05). Among the early risk factors, there are resorption of bone tissue at the cement-bone interface in the form of a light strip (with location in zones 1, 2, 3, 4 according to Hyojeong Mulcahy and Felix S. Chew) in the distal femur (t = 4.95 and higher, p < 0.05), the proximal tibia (t = 1.52 and above, p < 0.05), dynamic test for instability and ultrasound criteria for loosening (signs of hypervascularization, synovitis with a fluid volume of more than 50 cm3). Among the late instability risk factors, we identified changes at the cement-bone and implant-cement interface, with localization in the protrusion zones (5, 6, 7 according to Hyojeong Mulcahy and Felix S. Chew) in the femoral (t = 1.63 and higher, p < 0.05) and tibial areas (t = 1.36 and above, p < 0.05). The factors that influenced the development of stiffness in the prosthetic joint were operative interventions before arthroplasty (t = 1.53 and higher, p < 0.05), early complications (t = 1.49 and above, p < 0.05), concomitant diseases in the past medical history (хi2 = 4.55, p < 0.05), damage to the ligaments (хi2 = 7.55, p < 0.05), nerves, vessels during arthroplasty (хi2 = 6.55, p < 0.05), residual deformities of the limb axis (хi2 = 4.55, p < 0.05). Conclusions. Based on the studied factors that probably influenced the results of revision surgeries, a systematic approach to the evaluation of the outcomes of revision knee replacement is proposed, which will help avoid postoperative complications and improve the quality of treatment of this complex category of patients.
