Evaluation of the correlation between body mass index and radiological measurements around the knee: Aydin index

This study aimed to assess the relationship between body mass index (BMI) and the evaluation of bone and soft tissue structures around the knee. Various measurements were obtained from knee radiographs of 984 patients who presented to the outpatient clinic between January 2024 and January 2025. Height, weight, and BMI values were documented at the time of presentation. The correlation between the obtained measurements and BMI was analyzed. The measurements and proportional values with the highest correlation with BMI were identified. In the anteroposterior knee radiographs, the strongest correlation with BMI was observed in the distance between the lateral skin and the lateral femoral cortex in the coronal plane (Pearson correlation; 0.346, p<0.001). In the sagittal plane, the strongest correlation with BMI was found in the distance between the posterior skin and the posterior femoral cortex (Pearson correlation; 0.167, p<0.001). The strongest correlation with BMI was found in the ratio of the distance between the lateral femoral border at the medial epicondyle level and the skin to the total skin-to-skin distance (p=0.417, p<0.001). This study demonstrated a statistically significant relationship between various measurements and proportional indices around the knee and BMI. We believe that proportional measurements around the knee can provide a measure of BMI in cases where data records are insufficient or in patients with a history of prior surgery that limits BMI evaluation.