RESUMEN
INTRODUCTION: Tibial slope is a parameter that is important to recognize in knee kinematics and knee surgery. A very wide range of values governing posterior tibial slope exist in the literature. This study is based on the hypothesis that age, gender and region may have an effect on the tibial slope. MATERIALS AND METHODS: A total of 1800 lateral knee radiographies from five different countries [Turkey, Germany, Italy, Spain, and the United Kingdom (UK)] were utilized to measure the native posterior tibial slope. Participants were categorized in deciles with each decade of age after 40 years determined as a separate age group. Accordingly, four different age categories were formed in total, namely, the 40- to 49-, 50- to 59-, 60-69, and 70- to 79-year-old groups. Patients with severe knee osteoarthritis, those with a history of arthroscopic and open surgery around the knee, and those with severe morbid obesity and those outside the specified age group were excluded from the study. The angle between the line tangential to the medial tibial plateau and the proximal anatomical axis of the tibia was measured. RESULTS: The tibial slope values of both males and females in the Turkish population were found to be higher than those in other populations. It was observed that tibial slope values increased with age in females in all populations, except for those in the Spanish and UK populations. In the male population, it was found that tibial slope values increased with age in all populations except in the Spanish population. CONCLUSIONS: Region, age, and gender affect tibial slope in different populations in various ways. Our study shows that the region an individual lives in and living conditions affect the tibial slope.