Investigating the causal impact of body mass index on meniscus injuries: A 2-sample Mendelian randomization study

The aim of this study was to explore the possible causal association between body mass index (BMI) and meniscal injuries using Mendelian randomization (MR), a genetic research method. Relying on pooled data from a large genome-wide association study, we carefully selected a set of genetic variants as instrumental variables that were significantly associated with BMI and meniscal injuries and were independently distributed in populations of European origin. The potential impact of BMI on meniscal injuries was systematically assessed by implementing multiple MR analysis strategies including MR-Egger, weighted median and inverse variance weighting. In addition, heterogeneity and multiple validity tests were introduced in the study, together with the "leave-one-out" sensitivity analysis to ensure the robustness and reliability of the results. Inverse variance weighting analysis revealed a significant positive causal association between BMI and meniscus injury, as shown by the ratio (OR) and its 95% confidence interval of 1.46 (1.22-1.75), with a P-value of <.001. Further tests did not reveal significant heterogeneity and pleiotropy, and the results of the sensitivity analyses supported the robustness of the study findings. Combined with the use of 2-sample MR analysis, this study strongly confirms that BMI is an independent risk factor for meniscal injuries, and this finding provides a new genetic perspective for meniscal injury prevention and intervention.