Clinical Results Comparing Transtibial Technique and Outside in Technique in Single Bundle Anterior Cruciate Ligament Reconstruction

PURPOSE: To compare the clinical results of single-bundle anterior cruciate ligament (ACL) reconstruction using the conventional transtibial technique and the anatomical outside-in technique for femoral tunneling. MATERIALS AND METHODS: From 2007 to 2011, 89 patients who received ACL reconstruction were followed for ≥1 year were enrolled in the study. The conventional transtibial technique was used in 41 patients and the outside-in technique, in 48 patients. Femoral tunnel angle measurement and three-dimensional computed tomography (3D CT) were used for radiologic assessment of the location of femoral tunnel and Lysholm score and other tests were used for clinical assessment. RESULTS: Both techniques did not reveal statistical differences in the clinical assessment. However, in International Knee Documentation Committee subjective knee evaluation, the sum of two questionnaire items regarding instability showed a statistically significant difference (p=0.01). In the pivot shift test, the anatomical outside-in technique showed outstanding rotational stability over the transtibial technique (p=0.04). The mean femoral tunnel inclination in coronal plane were 69.2° and 30.3°, respectively, for both techniques, and 21.6° and 50.8°, respectively in sagittal plane, showing statistically significant differences on simple radiography (p=0.04, 0.05). A 3D CT was performed in 17 patients with the conventional transtibial technique and 25 patients with the outside-in technique. Coefficients of variation were 0.33 and 0.13, respectively, from dorsal border of the condyle and 0.67 and 0.24, respectively, from the roof of intercondylar notch. CONCLUSIONS: Femoral tunnels created with the outside-in technique have superior knee joint rotational stability compare to the transtibial technique. Therefore, the outside-in technique could be considered as a valuable technique in single-bundle ACL reconstruction.