The variation of the posterior tibial slope in South Indians: A hospital-based study of 290 cases

Background: The knowledge of the normal posterior tibial slope (PTS) is important for orthopaedic surgeons during joint replacement surgeries. Inadequate tibial cuts to replicate the normal tibial slope would lead to the tibial plate loosening or restriction of complete flexion. The tibial slope varies with age, gender, race and the ethnicity. We studied the tibial slope in the South Indian population. Aim: The aim of the study was to evaluate the PTS in a Southern Indian population and compare with the different known values across geographical and ethnic variations. Materials and Methods: The prospective study was conducted using the plain radiographs of the knee joint of 290 adult patients (age ranging from 18 to 81 years old with skiagrams showing complete epiphyseal fusion around the knee) collected over a period of 1 year from 10th January 2017 to 5th January 2018. Collected data were analysed statistically using SPSS (Statistical Package for the Social Sciences software) version 21 software. Results: The PTS varied between −5° and 21° with a mean value of 10.3771° ± 4.59482°. The mean PTS in males was 10.1232° ± 4.69607° and in females was 10.8825° ± 4.36616°. The mean PTS was highest (12.279) in the patients aged between 61 and 75 years of age and was least (8.243) in patients aged more than 75 years of age. There was a significant variation (P = 0.01) in the mean PTS in each age group of our study population [Table 1]. Conclusion: The tibial slope has been reported to vary in different ethnic subsets. In this study, the PTS varied between −5° and 21° with a mean value of 10.3771° ± 4.59482°. There was no statistical significant gender-based variation in the PTS. The PTS was lower than the PTS of the American, Nigerian and Chinese Populations but higher than the French population. We attempt to publish our results of the anatomical variation of the tibial slope in the Indian subcontinent.