Body Mass Index and Risk of Internal Knee Derangement: A Mendelian Randomization Study

Background: Traditional observational studies have found an increased risk of internal knee derangement (IKD) associated with higher body mass index (BMI). Here, we hypothesized that BMI and the risk of IKD have a causal relationship, and that high BMI is more likely to suffer from IKD. Method By reading the results of previous studies, we can assume that high BMI can increase the risk of IKD. The instrumental variables of BMI were obtained from the GIANT GWAS meta-analysis, which included approximately 700,000 individuals of European descent (n = 681,275). The IKD genetic data from IEU database, comprising 16,380,251 SNPs of European population. We performed MR analysis mainly by inverse-variance weighted (IVW), MR-Egger, Weighted median. In order to test the robustness of the correlation, we further conducted sensitivity analysis through Cochran’s Q test, MR-Egger intercept test and leave-one-out analysis. Results Genetic predisposition to higher BMI by 1 SD (SD = 4.8kg/m 2 ) was associated with 49% higher risk of IKD (OR = 1.491; [95%CI: 1.373–1.619]; p = 1.932e-21༜0.05). Sensitivity analysis was consistent with causal interpretation, which shows that there is unlikely to be a major bias in genetic pleiotropy. Conclusions Our findings indicated that high BMI predicted by genes exerts a causal effect on increasing the risk of IKD. Further research is required to unravel the mechanism of BMI in IKD prevention.