Anatomical Variations in the Posterior Tibial Slope in the North Indian Population: A Hospital-Based Study

Background: The measurement of the posterior tibial slope (PTS) angle is crucial for various knee surgeries such as total knee replacement, high tibial osteotomy, and anterior cruciate ligament reconstruction. This hospital-based study aimed to determine the average PTS angle in the knee joints of the North Indian population and provided valuable data to aid knee surgeries in this region. Methods: An analysis of 200 plain X-ray films, specifically the true lateral view of both knees in 20-degree flexion, was conducted on participants who exhibited skeletal maturity with no arthritis, tumours, or previous knee surgeries. The PTS measurements were performed manually. The data were analyzed statistically by matching them with variables such as gender, age, laterality, and body mass index (BMI). Results: The study revealed the following findings for the posterior tibial slope in a section of the North Indian population: there was no significant laterality difference (right knee: 12.76±2.35°, left knee: 12.55±2.46°); no notable sexual dimorphism (males: right knee - 12.79±2.65°, left knee - 12.25±2.65°, females: right knee - 12.73±2.11°, left knee - 12.77±2.30°). However, as age advanced, there were significant differences observed (PTS: 14.27±1.28° and 13.84±1.80° in the 18-40 years age group, 11.36±1.76° and 11.31±1.97° in the 41-60 years age group, 10.32±2.82° and 10.56±3.04° in the >60 years age group for the right and left knee, respectively). No significant correlation was found with BMI (PTS: 13.12±3.13° and 12.59±3.14° for BMI <25, 12.88±2.15° and 12.80±2.34° for BMI 25-30, 12.00±2.09° and 11.66±2.99° for BMI >30 in the right and left knee, respectively). Conclusions: The study demonstrated significant variations in the posterior tibial slope based on age, emphasizing the need for individualized treatment in knee surgeries. The research provided valuable insights into normal PTS values specific to the North Indian population, offering regional data to inform knee surgery procedures.