Statistical analysis
osteolysis
OSTEOLYSIS
All statistical evaluations were performed using NCSS 10 Statistical Software (2015, NCSS, LLC. Kaysville, Utah, USA) and R 4.1.0 (R Core Team. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing; 2021). The patients’ age in each group was compared using the Mann–Whitney test. Fisher's exact test was used for analysis of further data: (1) the difference between the sex of patients in both groups, (2) the difference between the occurrence of subsidence and osteolysis in both groups. Extended Fisher's exact test was used for analysis of further intergroup differences: (1) in the surgery level, (2) in the time of fusion initialization, (3) in the distribution of fusion quality grades at 18 months after the surgery, (4) in the time of quality grade I fusion achievement. 