Abstract. Introduction The study deals with the approaches to the analysis of the dynamics in the course of a long-term postoperative period in patients who underwent hip arthroplasty. Aim To feature the variants in the course of a long-term postoperative period in patients who underwent arthroplasty of the hip joint. Materials and methods 806 patients (age range, 9 to 88 years) suffering from osteoarthritis underwent primary total hip arthroplasty (THA). Statistical analysis was carried out using the R programming language, freely available at https://cran.r-project.org. The probability of maintaining satisfactory quality of life (QoL) at a certain time of observation t (year of observation) was assessed with the Kaplan-Meier method. To compare the likelihood of maintaining a satisfactory QoL level throughout the observation period in several groups (for example, patients of different sexes), the logrank test was used. Results By year 6 of follow-up, the following tendency emerges regarding the age of the patients. The indicators are the best in young patients (up to 44 years old), where the probability of maintaining a satisfactory QoL evaluation was 0.92 (0.84; 0.96). A somewhat lower values were observed in the patients of the middle age group (from 45 to 64 years old) – 0.87 (0.78; 0.92). Excellent and good QoL was found in patients aged 65 and older, 0.83 (0.76; 0.88). Discussion Survival analysis methods have been used for the first time in traumatology and orthopedics. Previous researchers assessed the long-term results of the quality of specialized traumatological and orthopedic care without considering censored observations. Thus, the coverage of the investigated clinical observations averaged 80-85%. Information about 10-15% of cases was excluded from the studies. The proposed method of analysis provides information about all patients. Conclusions Five years following THA, an excellent and good quality of life could be expected in 85 % of patients. Satisfactory and poor levels are observed in 15 % of patients. At 5-year follow-up after THA, the quality of life is worse in older female groups with severe concomitant pathology; however, there are no statistically significant differences. This is a tendency, and requires further study.

BACKGROUND: In recent years, in traumatology and orthopedics, statistical methods of survival analysis have been used to assess long-term treatment results, which make it possible to take into account censored clinical observations. This method of statistical analysis allows to take into account both cases of attrition from care and cases of incomplete follow-ups. There is no concurrent point of view on the dependence of the long-term results of hip and knee arthroplasty on the comorbidity of a patient. This circumstance fosters a special study using survival analysis. AIM: To study the long-term results of total hip and knee arthroplasty in the patients with osteoarthritis. To determine the patients quality of life depending on the presence of pronounced concomitant pathology. MATERIALS AND METHODS: The groups of patients with comorbidity and without significant concomitant pathology have been compared. The first group included 806 patients aged 19 to 88 years who underwent primary total hip replacement in the Clinic of Traumatology and Orthopedics of the North-Western State Medical University named after I.I. Mechnikov from 2014 to 2018 in connection with osteoarthritis. The second group consisted of 376 patients aged 43 to 85 years who underwent primary total KR due to osteoarthritis in the V.A. Baranov Republican Hospital (Petrozavodsk) in 20162019. Statistical data processing and graph design have been carried out with R programming language with open access via https://cran.r-project.org. The probability of maintaining a satisfactory assessment of the quality of life by a certain observation point t (year of observation) has been assessed using the KaplanMayer method. The logrank test has been used in order to compare the probability of maintaining a satisfactory assessment of quality of life during the entire follow-up period in the groups of patients with and without polymorbidity. RESULTS: At the end of the 5th year of follow-up, the probability of maintaining excellent and good quality of life after hip replacement with a 95% confidence interval was 0.88 (0.81; 0.94) in the patients without comorbidity, 0.84 (0.79; 0.88) in the patients with severe concomitant pathology. Test statistics (Z = 0.93) and p = 0.31 indicate statistically insignificant differences in survival curves between the groups of patients with varying degrees of comorbidity. When analyzing the five-year results of the knee replacement, the quality of life among patients with high and low comorbidity did not differ significantly. The probability of excellent and good quality of life at the 5th year of follow-up in practically healthy patients and in cases of mild therapeutic disease was 0.78 (0.67; 0.88); with a high degree of comorbidity 0.74 (0.65; 0.81). CONCLUSIONS: By the end of the 5th year of follow-up of the patients who have undergone hip or knee replacement due to osteoarthritis, an excellent and good quality of life can be expected on average in 80% of the patients. Satisfactory and unsatisfactory in 20% of the patients. Excellent and good quality of life 5 years after hip or knee arthroplasty in the patients with severe comorbidity does not significantly differ from that in the practically healthy patients without comorbidity (р 0,05).