The significance of guiding anterior cruciate ligament revision: a modified femoral tunnel classification

Abstract

Background The positioning error of femoral tunnel was the key factor leading to the failure of anterior cruciate ligament (ACL) reconstruction. This study aimed to propose a new femoral tunnel classification to guide ACL revision process. Methods Totals of 150 patients with ACL reconstruction failure from 2016 and 2023 were enrolled in this retrospective study. According to the tunnel diameter, shape, back wall and the positioning relationship with the Lateral Intercondylar Ridge on the three-dimensional CT imaging, we divided the femoral tunnels into four types: Type I off-target type, Type Ⅱ straddled type, Type Ⅲ anatomical type, and Type IV irregular type. Finally, explored the inter-observer reliability within two groups of doctors (Group A, 12 high seniorities; Group B, 12 low seniorities), and evaluated the intra-observer reliability within 6 doctors after two months. Results Among 150 cases of femoral tunnel three-dimensional CT reconstructed imaging, 144 cases were successfully included in the classification system, and 6 cases were confirmed as uncertain type. We measured the Kappa (κ) coefficient of group A was significantly higher than that of group B (κ 0.72 VS 0.68), and the κ coefficient of group A was still higher than group B (κ 0.69 VS 0.62) after further dividing Type Ⅲ anatomical type into three subtypes. In addition, the κ coefficients of intra-observer reliability were all exceeded 0.73. Conclusion The new femoral tunnel classification was reliable and had clinical guiding significance based on three-dimensional CT imaging. Level of evidence Level Ⅲ