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.