The purpose of the study was to compare prospectively and randomly two ACL reconstruction single bundle techniques, one referred to as traditional and the other referred to as anatomical, where the coronal angulation of the femoral tunnel aimed a more horizontal position at 2 and 10 o'clock. Orthopilot® System (Aesculap, Tuttlingen, Germany) was used to assist tunnel positioning in order to obtain and register translational and rotational stability.

Eighteen patients (14 men and 4 women), average age 33.8 years (range 18 to 49), with isolated ACL lesion were randomized in two groups, A (Conventional) and B (Anatomical). All patients were submitted to ACL navigated arthroscopic reconstruction with quadruple hamstrings grafts. Anteromedial portal access for femoral tunnel drilling was used in all patients. The tibial and femoral tunnels drillings were monitored by the Aesculap® Orthopilot Navigation System. In Group A, the femoral tunnel positioning aimed isometricity. In Group B, femoral tunnel was drilled at 25% of Blumensaat's line length from the posterior cortex, and 30° orientation in coronal plane. Initial and final Maximum Anterior tibial Displacement (MATD), Internal Tibial Rotation (ITR) and External Tibial Rotation (ETR) at 30° knee flexion data were recorded intra operatively by the navigation system.

No horizontal or rotational stability differences were found for MATD (p = 0.68), ITR (p = 014) and ETR (0.13). This study did not support the hypothesis that a more anatomical positioning leads to better rotational or anterior stability.