Tunnel Design and Measurement in All-Epiphyseal Anterior Cruciate Ligament Reconstruction

To investigate the characteristics of femoral condyles and tibial plateau in skeletally immature patients of different ages and designed the placement and orientation of the femoral and tibial tunnels for all-epiphyseal anterior cruciate ligament reconstruction (ACLR). CT data of patients who met the inclusion criteria from January 2014 to June 2024 were collected for analysis. 3D image models were reconstructed. The all-epiphyseal femoral and tibial tunnels were simulated on the model: the femoral tunnel started from the footprint area of ACL and ended laterally or anterolaterally (15°, 30° and 45°) at the lateral femoral cortex. The tibial tunnel begins at the footprint between the intercondylar ridges of the tibial. Tibial tunnel goes obliquely forward and above the epiphyseal line either laterally or medially at 0°, 15°, 30° and 45° with the coronal plane. The length of the tibial and femoral tunnels and the transverse and anteroposterior diameters of the femoral condyles and tibial plateau were measured. A total of 84 skeletally immature knee joints were included in this study and divided into 3 groups based on their ages (Group 1: [7–10), Group 2: [10−13) and Group 3: [13−16) years). The transverse diameter and the anteroposterior diameter of the femoral condyle increased with age (61.90 ± 4.44 vs 67.94 ± 5.33 vs 76.33 ± 5.47 and 44.51 ± 6.01 vs 52.68 ± 5.71 vs 60.45 ± 3.77, respectively, p <0.001). The transverse diameter and the anteroposterior diameter of the tibial plateau increased with age (55.88 ± 5.13 vs 62.34 ± 4.69 vs 70.51 ± 4.38 and 35.00 ± 4.13 vs 40.37 ± 4.89 vs 47.43 ± 3.00, respectively, p <0.001). Significant differences in femoral and tibial tunnel length were observed at all angles. The femoral tunnel length increased with the angle across all age groups, with patients in group 3 showing the highest values (25.21 ± 2.92 at 0° and 39.75 ± 3.13 at 45°). Similarly, tibial tunnel lengths increased with the angle and age. Group 3 had the longest tibial tunnel lengths with 42.43 ± 3.11 laterally at 45°. The risk of damaging surrounding tissues is relatively low when the femoral tunnel angle is within 30°. However, as the angle increases beyond 30°, the risk may increase. The femoral condyles and tibial plateau development of adolescents differs in ages. The all-epiphyseal ACLR at an appropriate angle can establish bone tunnels with sufficient length and avoid damage to the stable structures around the knee joint.